Using Python Virtual Environments

Different Python projects depend on different packages. To keep them separated and avoid polluting the global space with package installations we can use the concept of virtual environments. There are several ways to work with virtual environments in Python:

• virtualenv
• virtualenvwrapper
• Conda (part of Anaconda)

virtualenv

Virtualenv — virtualenv 20.3.2.dev1+g7185e57 documentation

To use virtualenv we first need to install all necessary components:

$ sudo apt update
$ sudo apt install python3-dev python3-pip
$ sudo pip3 install -U virtualenv  # system-wide install

Verification:

$ python3 --version
$ pip3 --version
$ virtualenv --version

or

$ virtualenv

usage: virtualenv [--version] [--with-traceback] [-v | -q] [--read-only-app-data] [--app-data APP_DATA] [--reset-app-data] [--upgrade-embed-wheels] [--discovery {builtin}] [-p py] [--try-first-with py_exe]

                  [--creator {builtin,cpython3-posix,venv}] [--seeder {app-data,pip}] [--no-seed] [--activators comma_sep_list] [--clear] [--no-vcs-ignore] [--system-site-packages] [--symlinks | --copies] [--no-download | --download]

                  [--extra-search-dir d [d ...]] [--pip version] [--setuptools version] [--wheel version] [--no-pip] [--no-setuptools] [--no-wheel] [--no-periodic-update] [--symlink-app-data] [--prompt prompt] [-h]

                  dest

virtualenv: error: the following arguments are required: dest

SystemExit: 2

or

$ virtualenv --help

usage: virtualenv [--version] [--with-traceback] [-v | -q] [--read-only-app-data] [--app-data APP_DATA] [--reset-app-data] [--upgrade-embed-wheels] [--discovery {builtin}] [-p py] [--try-first-with py_exe]

                  [--creator {builtin,cpython3-posix,venv}] [--seeder {app-data,pip}] [--no-seed] [--activators comma_sep_list] [--clear] [--no-vcs-ignore] [--system-site-packages] [--symlinks | --copies] [--no-download | --download]

                  [--extra-search-dir d [d ...]] [--pip version] [--setuptools version] [--wheel version] [--no-pip] [--no-setuptools] [--no-wheel] [--no-periodic-update] [--symlink-app-data] [--prompt prompt] [-h]

                  dest

optional arguments:

  --version                     display the version of the virtualenv package and its location, then exit

  --with-traceback              on failure also display the stacktrace internals of virtualenv (default: False)

  --read-only-app-data          use app data folder in read-only mode (write operations will fail with error) (default: False)

  --app-data APP_DATA           a data folder used as cache by the virtualenv (default: /home/bojan/.local/share/virtualenv)

  --reset-app-data              start with empty app data folder (default: False)

  --upgrade-embed-wheels        trigger a manual update of the embedded wheels (default: False)

  -h, --help                    show this help message and exit

verbosity:

  verbosity = verbose - quiet, default INFO, mapping => CRITICAL=0, ERROR=1, WARNING=2, INFO=3, DEBUG=4, NOTSET=5

  -v, --verbose                 increase verbosity (default: 2)

  -q, --quiet                   decrease verbosity (default: 0)

discovery:

  discover and provide a target interpreter

  --discovery {builtin}         interpreter discovery method (default: builtin)

  -p py, --python py            interpreter based on what to create environment (path/identifier) - by default use the interpreter where the tool is installed - first found wins (default: [])

  --try-first-with py_exe       try first these interpreters before starting the discovery (default: [])

creator:

  options for creator builtin

  --creator {builtin,cpython3-posix,venv}

                                create environment via (builtin = cpython3-posix) (default: builtin)

  dest                          directory to create virtualenv at

  --clear                       remove the destination directory if exist before starting (will overwrite files otherwise) (default: False)

  --no-vcs-ignore               don't create VCS ignore directive in the destination directory (default: False)

  --system-site-packages        give the virtual environment access to the system site-packages dir (default: False)

  --symlinks                    try to use symlinks rather than copies, when symlinks are not the default for the platform (default: True)

  --copies, --always-copy       try to use copies rather than symlinks, even when symlinks are the default for the platform (default: False)

seeder:

  options for seeder app-data

  --seeder {app-data,pip}       seed packages install method (default: app-data)

  --no-seed, --without-pip      do not install seed packages (default: False)

  --no-download, --never-download

                                pass to disable download of the latest pip/setuptools/wheel from PyPI (default: True)

  --download                    pass to enable download of the latest pip/setuptools/wheel from PyPI (default: False)

  --extra-search-dir d [d ...]  a path containing wheels to extend the internal wheel list (can be set 1+ times) (default: [])

  --pip version                 version of pip to install as seed: embed, bundle or exact version (default: bundle)

  --setuptools version          version of setuptools to install as seed: embed, bundle or exact version (default: bundle)

  --wheel version               version of wheel to install as seed: embed, bundle or exact version (default: bundle)

  --no-pip                      do not install pip (default: False)

  --no-setuptools               do not install setuptools (default: False)

  --no-wheel                    do not install wheel (default: False)

  --no-periodic-update          disable the periodic (once every 14 days) update of the embedded wheels (default: False)

  --symlink-app-data            symlink the python packages from the app-data folder (requires seed pip>=19.3) (default: False)

activators:

  options for activation scripts

  --activators comma_sep_list   activators to generate - default is all supported (default: bash,cshell,fish,powershell,python,xonsh)

  --prompt prompt               provides an alternative prompt prefix for this environment (default: None)

config file /home/bojan/.config/virtualenv/virtualenv.ini missing (change via env var VIRTUALENV_CONFIG_FILE)

Create virtual environment (we chose to use python3 as Python interpreter and venv as the directory where to store virtual environment):

$ virtualenv -p python3 ./venv_dir_name

or

$ virtualenv --system-site-packages -p python3 ./venv_dir_name

From virtualenv · PyPI:

If you build with virtualenv --system-site-packages ENV, your virtual environment will inherit packages from /usr/lib/python2.7/site-packages (or wherever your global site-packages directory is).

This can be used if you have control over the global site-packages directory, and you want to depend on the packages there. If you want isolation from the global system, do not use this flag. BK: This flag should be avoided as it defeats the entire point of virtualenvs (which is why --no-site-packages was made the default).

Example:

$ virtualenv -p python3 ./venv

created virtual environment CPython3.8.5.final.0-64 in 253ms

  creator CPython3Posix(dest=/home/bojan/dev/github/python-demo/venv, clear=False, no_vcs_ignore=False, global=False)

  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=/home/bojan/.local/share/virtualenv)

    added seed packages: pip==20.3.3, setuptools==51.1.2, wheel==0.36.2

  activators BashActivator,CShellActivator,FishActivator,PowerShellActivator,PythonActivator,XonshActivator

I once experienced this error when tried to create a virtual environment:

$ virtualenv -p python3 ./venv

Traceback (most recent call last):

  File "/usr/local/bin/virtualenv", line 5, in <module>

    from virtualenv.__main__ import run_with_catch

  File "/usr/local/lib/python3.8/dist-packages/virtualenv/__init__.py", line 3, in <module>

    from .run import cli_run, session_via_cli

  File "/usr/local/lib/python3.8/dist-packages/virtualenv/run/__init__.py", line 6, in <module>

    from ..app_data import make_app_data

  File "/usr/local/lib/python3.8/dist-packages/virtualenv/app_data/__init__.py", line 9, in <module>

    from appdirs import user_data_dir

ModuleNotFoundError: No module named 'appdirs'

I then installed the missing module via pip but this showed another error:

$ sudo pip3 install appdirs

Collecting appdirs

  Downloading appdirs-1.4.4-py2.py3-none-any.whl (9.6 kB)

ERROR: virtualenv 20.3.1 requires filelock<4,>=3.0.0, which is not installed.

Installing collected packages: appdirs

Successfully installed appdirs-1.4.4

I resolved this by reinstalling the virtualenv:

$ sudo pip3 install virtualenv

Requirement already satisfied: virtualenv in /usr/local/lib/python3.8/dist-packages (20.3.1)

Requirement already satisfied: appdirs<2,>=1.4.3 in /usr/local/lib/python3.8/dist-packages (from virtualenv) (1.4.4)

Requirement already satisfied: six<2,>=1.9.0 in /usr/lib/python3/dist-packages (from virtualenv) (1.14.0)

Requirement already satisfied: distlib<1,>=0.3.1 in /usr/local/lib/python3.8/dist-packages (from virtualenv) (0.3.1)

Collecting filelock<4,>=3.0.0

  Downloading filelock-3.0.12-py3-none-any.whl (7.6 kB)

Installing collected packages: filelock

Successfully installed filelock-3.0.12

Once virtual environment is created, we'll have venv/bin/activate script created. Let's explore it:

$ cat venv/bin/activate
...

deactivate() {

...

}

...

VIRTUAL_ENV="/home/bojan/dev/github/tensorflow-demo/venv"
export VIRTUAL_ENV

_OLD_VIRTUAL_PATH="$PATH"
PATH="$VIRTUAL_ENV/bin:$PATH"
export PATH

...

pydoc () {

    python -m pydoc "$@"

}

...

We can see that we'll now have a new environment variable set - VIRTUAL_ENV and also a deactivate commmand.

To activate virtual environment:

$ source ./venv/bin/activate

We can also use a dot command:

$ . ./venv/bin/activate

When virtual environment is active, your shell prompt is prefixed with its name in form: (venv).

(venv) $ which pip

/home/bojan/dev/github/python-demo/venv/bin/pip

(venv) $ which pip3

/home/bojan/dev/github/python-demo/venv/bin/pip3

If we've saved requirements.txt, we can install all dependencies now with on of the following commands (see Python Package Management with pip | My Public Notepad):

$ pip install -r requirements.txt

$ pip3 install -r requirements.txt

$ pip3 install -r requirements.txt --verbose

Installing packages using pip and virtual environments — Python Packaging User Guide

It is possible to install a single new package in the virtual environment:

$ pip install package_name

python - How to install a package inside virtualenv? - Stack Overflow

Example:

(venv) $ pip3 install psycopg2

Collecting psycopg2

  Using cached psycopg2-2.8.6-cp38-cp38-linux_x86_64.whl

Installing collected packages: psycopg2

Successfully installed psycopg2-2.8.6

To verify installation path:

(venv) $ pip3 show psycopg2

Name: psycopg2

Version: 2.8.6

Summary: psycopg2 - Python-PostgreSQL Database Adapter

Home-page: https://psycopg.org/

Author: Federico Di Gregorio

Author-email: fog@initd.org

License: LGPL with exceptions

Location: /home/user/dev/my-app/venv/lib/python3.8/site-packages

Requires: 

Required-by: 

To check the version of the package installed in virtual environment:

(venv) $ pip3 list | grep psycopg

psycopg2          2.8.6

To exit virtual environment:

(venv) $ deactivate

How to rename virtual environment?

directory - How to rename a virtualenv in Python? - Stack Overflow

From inside active virtual environment:

$ pip freeze > requirements.txt
$ deactivate

From python - Pip freeze vs. pip list - Stack Overflow: 

pip list shows ALL packages. 

pip freeze shows packages YOU installed via pip (or pipenv if using that tool) command in a requirements format.

Also, be aware of `$ pip freeze > requirements.txt` considered harmful. 

Then delete old environment directory. E.g.

$ rm -r ~/python-envs/tensorrt-5.1.5.1-tensorflow-1.14.0/

...and create a new one with correct name:

$ python3 -m virtualenv -p python3 ~/python-envs/tensorrt-5.1.5.1-tensorflow-1.15.0
Already using interpreter /usr/bin/python3
Using base prefix '/usr'
New python executable in /home/nvidia/python-envs/tensorrt-5.1.5.1-tensorflow-1.15.0/bin/python3
Also creating executable in /home/nvidia/python-envs/tensorrt-5.1.5.1-tensorflow-1.15.0/bin/python
Installing setuptools, pkg_resources, pip, wheel...done.

Activate it and install all packages from the saved list:

$ source ~/python-envs/tensorrt-5.1.5.1-tensorflow-1.15.0/bin/activate

$ pip install -r requirements.txt

$ pip3 install --extra-index-url https://developer.download.nvidia.com/compute/redist/jp/v43 tensorflow-gpu==1.15.0+nv19.12

virtualenvwrapper

TBD...

Conda

Managing Python Environments with Conda | My Public Notepad

References

Setting up your python development environment (with pyenv, virtualenv, and virtualenvwrapper)
The Right Way to Use Virtual Environments
Pipenv & Virtual Environments
Create a virtual environment 
Virtual Environments and Packages
Python Virtual Environments: A Primer

An Introduction To Venv

Conda, OpenCV and GUI backends

It is possible to manage OpenCV package installation via conda manager.

I have an environment defined by e.g. my_env_config.yml:

name: my_env

channels:

  - menpo

  - conda-forge

  - defaults

dependencies:

  ...

  - opencv=3.4.2

  ...

This installs the following packages:

(my_env) $ conda list

...

libopencv                 3.4.2                hb342d67_1 

opencv                    3.4.2            py36h6fd60c2_1  

py-opencv                 3.4.2            py36hb342d67_1 

...

In Jupyter Notebook:

import cv2

img = cv2.imread('../data/test.jpg')

cv2.imshow('Test, img)

cv2.waitKey()

...fails with:

Output:

---------------------------------------------------------------------------

error                                     Traceback (most recent call last)

<ipython-input-1-da1c1c679272> in <module>

      1 import cv2

      2 img = cv2.imread('../data/test.jpg')

----> 3 cv2.imshow('Test', img)

      4 cv2.waitKey()

error: OpenCV(3.4.2) /tmp/build/80754af9/opencv-suite_1535558553474/work/modules/highgui/src/window.cpp:632: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function 'cvShowImage'

Trying to display an image also fails when trying to do that from python terminal:

import cv2    

import numpy as np

cv2.imshow('darkness', np.zeros((100, 100)))

cv2.waitKey()

...fails with:

(my-env) $ python 

Python 3.6.6 | packaged by conda-forge | (default, Oct 12 2018, 14:43:46) 

[GCC 7.3.0] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> import cv2

>>> import numpy as np

>>> cv2.imshow('test', np.zeros((100, 100)))

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

cv2.error: OpenCV(3.4.2) /tmp/build/80754af9/opencv-suite_1535558553474/work/modules/highgui/src/window.cpp:632: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function 'cvShowImage'

So the issue here is that OpenCV 3.4.2 for Ubuntu is not built against UI framework (e.g. GTK) which is required for cvShowImage() function to be defined. I am not sure why this error message suggests using only GTK as UI backend when there is another UI framework, Qt, which is also commonly used and which provides richer UI experience [GTK or QT when build OpenCV - OpenCV Q&A Forum]. In fact, OpenCV in conda-forge channel is built against it. We can check that by looking the source code https://github.com/conda-forge/opencv-feedstock/blob/master/recipe/build.sh:

QT="5"

...

cmake -LAH -G "Ninja"                                                     \

   ...

   -DWITH_GTK=0                                                          \

   -DWITH_QT=$QT                                                         \

   ...

Let's try to install OpenCV from that channel. First we need to remove the current OpenCV package:

(my-env) $ conda remove opencv

Collecting package metadata (repodata.json): done

Solving environment: done

## Package Plan ##

  environment location: /home/bojan/anaconda3/envs/my-env

  removed specs:

    - opencv

The following packages will be downloaded:

    package                    |            build

    ---------------------------|-----------------

    absl-py-0.10.0             |           py36_0         168 KB

    argon2-cffi-20.1.0         |   py36h7b6447c_1          46 KB

    astor-0.8.1                |           py36_0          47 KB

    async_generator-1.10       |   py36h28b3542_0          39 KB

    attrs-20.2.0               |             py_0          42 KB

    bleach-3.2.1               |             py_0         112 KB

    c-ares-1.16.1              |       h7b6447c_0         108 KB

    cffi-1.14.0                |   py36h2e261b9_0         223 KB

    cycler-0.10.0              |           py36_0          13 KB

    dbus-1.13.18               |       hb2f20db_0         504 KB

    decorator-4.4.2            |             py_0          14 KB

    defusedxml-0.6.0           |             py_0          23 KB

    entrypoints-0.3            |           py36_0          12 KB

    expat-2.2.10               |       he6710b0_2         153 KB

    freetype-2.10.4            |       h5ab3b9f_0         596 KB

    gast-0.4.0                 |             py_0          15 KB

    glib-2.63.1                |       h5a9c865_0         2.9 MB

    grpcio-1.14.1              |   py36h9ba97e2_0         944 KB

    gstreamer-1.14.0           |       hb453b48_1         3.1 MB

    h5py-2.10.0                |   py36hd6299e0_1         901 KB

    hdf5-1.10.6                |       hb1b8bf9_0         3.7 MB

    importlib-metadata-2.0.0   |             py_1          35 KB

    importlib_metadata-2.0.0   |                1          11 KB

    intel-openmp-2019.4        |              243         729 KB

    ipykernel-5.3.4            |   py36h5ca1d4c_0         181 KB

    ipython-7.16.1             |   py36h5ca1d4c_0         999 KB

    ipython_genutils-0.2.0     |           py36_0          39 KB

    ipywidgets-7.5.1           |             py_1          98 KB

    jedi-0.17.2                |           py36_0         916 KB

    jsonschema-3.2.0           |             py_2          47 KB

    jupyter_client-6.1.7       |             py_0          77 KB

    jupyter_console-6.2.0      |             py_0          26 KB

    jupyter_core-4.6.3         |           py36_0          71 KB

    jupyterlab_launcher-0.13.1 |             py_2          23 KB

    jupyterlab_pygments-0.1.2  |             py_0           8 KB

    keras-applications-1.0.4   |           py36_1          45 KB

    keras-preprocessing-1.0.2  |           py36_1          44 KB

    kiwisolver-1.2.0           |   py36hfd86e86_0          84 KB

    libffi-3.2.1               |    hf484d3e_1007          48 KB

    libprotobuf-3.13.0.1       |       hd408876_0         2.0 MB

    libxml2-2.9.10             |       hb55368b_3         1.2 MB

    lz4-c-1.9.2                |       heb0550a_3         175 KB

    markdown-3.3.2             |           py36_0         125 KB

    markupsafe-1.1.1           |   py36h7b6447c_0          29 KB

    mistune-0.8.4              |   py36h7b6447c_0          55 KB

    mkl-2018.0.3               |                1       126.9 MB

    mkl_fft-1.0.6              |   py36h7dd41cf_0         135 KB

    mkl_random-1.0.1           |   py36h4414c95_1         324 KB

    nbclient-0.5.1             |             py_0          58 KB

    nbconvert-6.0.7            |           py36_0         480 KB

    nbformat-5.0.8             |             py_0          88 KB

    nest-asyncio-1.4.1         |             py_0          10 KB

    notebook-6.1.4             |           py36_0         4.1 MB

    numpy-1.15.1               |   py36h1d66e8a_0          36 KB

    numpy-base-1.15.1          |   py36h81de0dd_0         3.4 MB

    pandoc-2.11                |       hb0f4dca_0         9.6 MB

    pandocfilters-1.4.2        |           py36_1          13 KB

    pexpect-4.8.0              |           py36_0          82 KB

    pickleshare-0.7.5          |           py36_0          13 KB

    pip-20.2.4                 |           py36_0         1.8 MB

    prompt-toolkit-3.0.8       |             py_0         248 KB

    prompt_toolkit-3.0.8       |                0          12 KB

    protobuf-3.13.0.1          |   py36he6710b0_1         633 KB

    ptyprocess-0.6.0           |           py36_0          23 KB

    pygments-2.7.1             |             py_0         671 KB

    pyqt-5.6.0                 |   py36h22d08a2_6         4.4 MB

    pyrsistent-0.17.3          |   py36h7b6447c_0          89 KB

    python-dateutil-2.8.1      |             py_0         215 KB

    pyyaml-5.3.1               |   py36h7b6447c_1         180 KB

    pyzmq-19.0.2               |   py36he6710b0_1         434 KB

    qt-5.6.3                   |       h8bf5577_3        36.4 MB

    qtconsole-4.7.7            |             py_0          96 KB

    qtpy-1.9.0                 |             py_0          38 KB

    readline-7.0               |       h7b6447c_5         324 KB

    scikit-learn-0.19.1        |   py36hedc7406_0         3.9 MB

    scipy-1.1.0                |   py36hfa4b5c9_1        13.2 MB

    send2trash-1.5.0           |           py36_0          16 KB

    setuptools-50.3.0          |   py36hb0f4dca_1         713 KB

    sip-4.18.1                 |   py36hf484d3e_2         261 KB

    sqlite-3.33.0              |       h62c20be_0         1.1 MB

    tbb-2020.3                 |       hfd86e86_0         1.1 MB

    tbb4py-2020.3              |   py36hfd86e86_0         200 KB

    termcolor-1.1.0            |           py36_1           8 KB

    terminado-0.9.1            |           py36_0          27 KB

    testpath-0.4.4             |             py_0          82 KB

    tornado-6.0.4              |   py36h7b6447c_1         597 KB

    traitlets-4.3.3            |           py36_0         140 KB

    webencodings-0.5.1         |           py36_1          19 KB

    wheel-0.35.1               |             py_0          37 KB

    widgetsnbextension-3.5.1   |           py36_0         862 KB

    zeromq-4.3.3               |       he6710b0_3         500 KB

    zipp-3.3.1                 |             py_0          12 KB

    zstd-1.4.5                 |       h9ceee32_0         619 KB

    ------------------------------------------------------------

                                           Total:       234.4 MB

The following NEW packages will be INSTALLED:

  gst-plugins-base   pkgs/main/linux-64::gst-plugins-base-1.14.0-hbbd80ab_1

  intel-openmp       pkgs/main/linux-64::intel-openmp-2019.4-243

  libedit            pkgs/main/linux-64::libedit-3.1.20191231-h14c3975_1

  libgfortran-ng     pkgs/main/linux-64::libgfortran-ng-7.3.0-hdf63c60_0

  mkl                pkgs/main/linux-64::mkl-2018.0.3-1

  mkl_fft            pkgs/main/linux-64::mkl_fft-1.0.6-py36h7dd41cf_0

  mkl_random         pkgs/main/linux-64::mkl_random-1.0.1-py36h4414c95_1

  numpy-base         pkgs/main/linux-64::numpy-base-1.15.1-py36h81de0dd_0

  tbb                pkgs/main/linux-64::tbb-2020.3-hfd86e86_0

  tbb4py             pkgs/main/linux-64::tbb4py-2020.3-py36hfd86e86_0

The following packages will be REMOVED:

  _openmp_mutex-4.5-1_gnu

  atk-2.25.90-hf2eb9ee_1001

  backports-1.0-py_2

  backports.functools_lru_cache-1.6.1-py_0

  bzip2-1.0.8-h516909a_3

  cairo-1.14.12-h80bd089_1005

  ffmpeg-4.0.2-ha0c5888_2

  freeglut-3.0.0-hf484d3e_1005

  gdk-pixbuf-2.36.12-h4f1c04b_1001

  gettext-0.19.8.1-hc5be6a0_1002

  gmp-6.1.2-hf484d3e_1000

  gnutls-3.5.19-h2a4e5f8_1

  gobject-introspection-1.56.1-py36h9e29830_1001

  graphite2-1.3.13-he1b5a44_1001

  gtk2-2.24.31-h5baeb44_1000

  harfbuzz-1.9.0-he243708_1001

  jasper-2.0.14-habb8e15_1

  libgfortran-3.0.0-1

  libglu-9.0.0-he1b5a44_1001

  libgomp-9.3.0-h5dbcf3e_17

  libiconv-1.16-h516909a_0

  libopencv-3.4.2-hb342d67_1

  libwebp-base-1.1.0-h516909a_3

  nettle-3.3-0

  openblas-0.2.20-8

  opencv-3.4.2-py36h6fd60c2_1

  openh264-1.8.0-hdbcaa40_1000

  pango-1.40.14-hf0c64fd_1003

  pixman-0.34.0-h14c3975_1003

  pthread-stubs-0.4-h14c3975_1001

  py-opencv-3.4.2-py36hb342d67_1

  python_abi-3.6-1_cp36m

  x264-1!152.20180806-h14c3975_0

  xorg-fixesproto-5.0-h14c3975_1002

  xorg-inputproto-2.3.2-h14c3975_1002

  xorg-kbproto-1.0.7-h14c3975_1002

  xorg-libice-1.0.10-h516909a_0

  xorg-libsm-1.2.3-h84519dc_1000

  xorg-libx11-1.6.12-h516909a_0

  xorg-libxau-1.0.9-h14c3975_0

  xorg-libxdmcp-1.1.3-h516909a_0

  xorg-libxext-1.3.4-h516909a_0

  xorg-libxfixes-5.0.3-h516909a_1004

  xorg-libxi-1.7.10-h516909a_0

  xorg-libxrender-0.9.10-h516909a_1002

  xorg-libxt-1.2.0-h516909a_0

  xorg-renderproto-0.11.1-h14c3975_1002

  xorg-xextproto-7.3.0-h14c3975_1002

  xorg-xproto-7.0.31-h14c3975_1007

The following packages will be UPDATED:

  dbus               conda-forge::dbus-1.13.0-h4e0c4b3_1000 --> pkgs/main::dbus-1.13.18-hb2f20db_0

  expat                 conda-forge::expat-2.2.9-he1b5a44_2 --> pkgs/main::expat-2.2.10-he6710b0_2

  freetype           conda-forge::freetype-2.10.2-he06d7ca~ --> pkgs/main::freetype-2.10.4-h5ab3b9f_0

  glib               conda-forge::glib-2.56.2-had28632_1001 --> pkgs/main::glib-2.63.1-h5a9c865_0

  gstreamer          conda-forge::gstreamer-1.12.5-h0cc048~ --> pkgs/main::gstreamer-1.14.0-hb453b48_1

  h5py               conda-forge::h5py-2.8.0-py36h3010b51_~ --> pkgs/main::h5py-2.10.0-py36hd6299e0_1

  hdf5                  conda-forge::hdf5-1.10.2-hc401514_3 --> pkgs/main::hdf5-1.10.6-hb1b8bf9_0

  importlib-metadata conda-forge/linux-64::importlib-metad~ --> pkgs/main/noarch::importlib-metadata-2.0.0-py_1

  importlib_metadata conda-forge::importlib_metadata-2.0.0~ --> pkgs/main::importlib_metadata-2.0.0-1

  jsonschema         conda-forge/linux-64::jsonschema-3.2.~ --> pkgs/main/noarch::jsonschema-3.2.0-py_2

  libprotobuf        conda-forge::libprotobuf-3.13.0-h8b12~ --> pkgs/main::libprotobuf-3.13.0.1-hd408876_0

  libxcb             conda-forge::libxcb-1.13-h14c3975_1002 --> pkgs/main::libxcb-1.14-h7b6447c_0

  libxml2             conda-forge::libxml2-2.9.9-h13577e0_2 --> pkgs/main::libxml2-2.9.10-hb55368b_3

  markdown           conda-forge/noarch::markdown-3.2.2-py~ --> pkgs/main/linux-64::markdown-3.3.2-py36_0

  nbclient                 conda-forge::nbclient-0.5.0-py_0 --> pkgs/main::nbclient-0.5.1-py_0

  nbformat                 conda-forge::nbformat-5.0.7-py_0 --> pkgs/main::nbformat-5.0.8-py_0

  pandoc              conda-forge::pandoc-2.10.1-h516909a_0 --> pkgs/main::pandoc-2.11-hb0f4dca_0

  pip                   conda-forge/noarch::pip-20.2.3-py_0 --> pkgs/main/linux-64::pip-20.2.4-py36_0

  prompt-toolkit     conda-forge::prompt-toolkit-3.0.7-py_0 --> pkgs/main::prompt-toolkit-3.0.8-py_0

  prompt_toolkit        conda-forge::prompt_toolkit-3.0.7-0 --> pkgs/main::prompt_toolkit-3.0.8-0

  protobuf           conda-forge::protobuf-3.13.0-py36h831~ --> pkgs/main::protobuf-3.13.0.1-py36he6710b0_1

  pyyaml             conda-forge::pyyaml-5.3.1-py36h8c4c3a~ --> pkgs/main::pyyaml-5.3.1-py36h7b6447c_1

  pyzmq              conda-forge::pyzmq-19.0.2-py36h9947db~ --> pkgs/main::pyzmq-19.0.2-py36he6710b0_1

  qt                    conda-forge::qt-5.6.2-hbe13537_1012 --> pkgs/main::qt-5.6.3-h8bf5577_3

  setuptools         conda-forge::setuptools-49.6.0-py36h9~ --> pkgs/main::setuptools-50.3.0-py36hb0f4dca_1

  sqlite              conda-forge::sqlite-3.28.0-h8b20d00_0 --> pkgs/main::sqlite-3.33.0-h62c20be_0

  zeromq               conda-forge::zeromq-4.3.3-he1b5a44_1 --> pkgs/main::zeromq-4.3.3-he6710b0_3

  zipp                         conda-forge::zipp-3.2.0-py_0 --> pkgs/main::zipp-3.3.1-py_0

The following packages will be SUPERSEDED by a higher-priority channel:

  _libgcc_mutex      conda-forge::_libgcc_mutex-0.1-conda_~ --> pkgs/main::_libgcc_mutex-0.1-main

  absl-py            conda-forge::absl-py-0.10.0-py36h9f0a~ --> pkgs/main::absl-py-0.10.0-py36_0

  argon2-cffi        conda-forge::argon2-cffi-20.1.0-py36h~ --> pkgs/main::argon2-cffi-20.1.0-py36h7b6447c_1

  astor              conda-forge/noarch::astor-0.8.1-pyh9f~ --> pkgs/main/linux-64::astor-0.8.1-py36_0

  async_generator    conda-forge/noarch::async_generator-1~ --> pkgs/main/linux-64::async_generator-1.10-py36h28b3542_0

  attrs              conda-forge::attrs-20.2.0-pyh9f0ad1d_0 --> pkgs/main::attrs-20.2.0-py_0

  backcall           conda-forge::backcall-0.2.0-pyh9f0ad1~ --> pkgs/main::backcall-0.2.0-py_0

  blas                       conda-forge::blas-1.1-openblas --> pkgs/main::blas-1.0-mkl

  bleach             conda-forge::bleach-3.2.1-pyh9f0ad1d_0 --> pkgs/main::bleach-3.2.1-py_0

  c-ares              conda-forge::c-ares-1.16.1-h516909a_3 --> pkgs/main::c-ares-1.16.1-h7b6447c_0

  cffi               conda-forge::cffi-1.14.3-py36h0ff685e~ --> pkgs/main::cffi-1.14.0-py36h2e261b9_0

  cycler             conda-forge/noarch::cycler-0.10.0-py_2 --> pkgs/main/linux-64::cycler-0.10.0-py36_0

  decorator                                     conda-forge --> pkgs/main

  defusedxml                                    conda-forge --> pkgs/main

  entrypoints        conda-forge::entrypoints-0.3-py36h9f0~ --> pkgs/main::entrypoints-0.3-py36_0

  fontconfig         conda-forge::fontconfig-2.13.1-he4413~ --> pkgs/main::fontconfig-2.13.0-h9420a91_0

  gast                 conda-forge::gast-0.4.0-pyh9f0ad1d_0 --> pkgs/main::gast-0.4.0-py_0

  grpcio             conda-forge::grpcio-1.16.0-py36h4f00d~ --> pkgs/main::grpcio-1.14.1-py36h9ba97e2_0

  icu                   conda-forge::icu-58.2-hf484d3e_1000 --> pkgs/main::icu-58.2-he6710b0_3

  ipykernel          conda-forge::ipykernel-5.3.4-py36h95a~ --> pkgs/main::ipykernel-5.3.4-py36h5ca1d4c_0

  ipython            conda-forge::ipython-7.16.1-py36h95af~ --> pkgs/main::ipython-7.16.1-py36h5ca1d4c_0

  ipython_genutils   conda-forge/noarch::ipython_genutils-~ --> pkgs/main/linux-64::ipython_genutils-0.2.0-py36_0

  ipywidgets         conda-forge::ipywidgets-7.5.1-pyh9f0a~ --> pkgs/main::ipywidgets-7.5.1-py_1

  jedi               conda-forge::jedi-0.17.2-py36h9f0ad1d~ --> pkgs/main::jedi-0.17.2-py36_0

  jinja2             conda-forge::jinja2-2.11.2-pyh9f0ad1d~ --> pkgs/main::jinja2-2.11.2-py_0

  jpeg                      conda-forge::jpeg-9d-h516909a_0 --> pkgs/main::jpeg-9b-h024ee3a_2

  jupyter_client                                conda-forge --> pkgs/main

  jupyter_console                               conda-forge --> pkgs/main

  jupyter_core       conda-forge::jupyter_core-4.6.3-py36h~ --> pkgs/main::jupyter_core-4.6.3-py36_0

  jupyterlab_launch~                            conda-forge --> pkgs/main

  jupyterlab_pygmen~ conda-forge::jupyterlab_pygments-0.1.~ --> pkgs/main::jupyterlab_pygments-0.1.2-py_0

  keras-applications conda-forge/noarch::keras-application~ --> pkgs/main/linux-64::keras-applications-1.0.4-py36_1

  keras-preprocessi~ conda-forge/noarch::keras-preprocessi~ --> pkgs/main/linux-64::keras-preprocessing-1.0.2-py36_1

  kiwisolver         conda-forge::kiwisolver-1.2.0-py36hdb~ --> pkgs/main::kiwisolver-1.2.0-py36hfd86e86_0

  libffi             conda-forge::libffi-3.2.1-he1b5a44_10~ --> pkgs/main::libffi-3.2.1-hf484d3e_1007

  libgcc-ng          conda-forge::libgcc-ng-9.3.0-h5dbcf3e~ --> pkgs/main::libgcc-ng-9.1.0-hdf63c60_0

  libpng              conda-forge::libpng-1.6.37-hed695b0_2 --> pkgs/main::libpng-1.6.37-hbc83047_0

  libsodium          conda-forge::libsodium-1.0.18-h516909~ --> pkgs/main::libsodium-1.0.18-h7b6447c_0

  libstdcxx-ng       conda-forge::libstdcxx-ng-9.3.0-h2ae2~ --> pkgs/main::libstdcxx-ng-9.1.0-hdf63c60_0

  libtiff             conda-forge::libtiff-4.1.0-hc7e4089_6 --> pkgs/main::libtiff-4.1.0-h2733197_1

  libuuid            conda-forge::libuuid-2.32.1-h14c3975_~ --> pkgs/main::libuuid-1.0.3-h1bed415_2

  lz4-c                 conda-forge::lz4-c-1.9.2-he1b5a44_3 --> pkgs/main::lz4-c-1.9.2-heb0550a_3

  markupsafe         conda-forge::markupsafe-1.1.1-py36h8c~ --> pkgs/main::markupsafe-1.1.1-py36h7b6447c_0

  mistune            conda-forge::mistune-0.8.4-py36h8c4c3~ --> pkgs/main::mistune-0.8.4-py36h7b6447c_0

  nbconvert          conda-forge::nbconvert-6.0.7-py36h9f0~ --> pkgs/main::nbconvert-6.0.7-py36_0

  ncurses               conda-forge::ncurses-6.2-he1b5a44_1 --> pkgs/main::ncurses-6.2-he6710b0_1

  nest-asyncio                                  conda-forge --> pkgs/main

  notebook           conda-forge::notebook-6.1.4-py36h9f0a~ --> pkgs/main::notebook-6.1.4-py36_0

  numpy              conda-forge::numpy-1.15.1-py36_blas_o~ --> pkgs/main::numpy-1.15.1-py36h1d66e8a_0

  packaging          conda-forge::packaging-20.4-pyh9f0ad1~ --> pkgs/main::packaging-20.4-py_0

  pandocfilters      conda-forge/noarch::pandocfilters-1.4~ --> pkgs/main/linux-64::pandocfilters-1.4.2-py36_1

  parso               conda-forge::parso-0.7.1-pyh9f0ad1d_0 --> pkgs/main::parso-0.7.0-py_0

  pcre                    conda-forge::pcre-8.44-he1b5a44_0 --> pkgs/main::pcre-8.44-he6710b0_0

  pexpect            conda-forge::pexpect-4.8.0-py36h9f0ad~ --> pkgs/main::pexpect-4.8.0-py36_0

  pickleshare        conda-forge::pickleshare-0.7.5-py36h9~ --> pkgs/main::pickleshare-0.7.5-py36_0

  prometheus_client  conda-forge::prometheus_client-0.8.0-~ --> pkgs/main::prometheus_client-0.8.0-py_0

  ptyprocess         conda-forge/noarch::ptyprocess-0.6.0-~ --> pkgs/main/linux-64::ptyprocess-0.6.0-py36_0

  pycparser          conda-forge::pycparser-2.20-pyh9f0ad1~ --> pkgs/main::pycparser-2.20-py_2

  pygments                                      conda-forge --> pkgs/main

  pyparsing          conda-forge::pyparsing-2.4.7-pyh9f0ad~ --> pkgs/main::pyparsing-2.4.7-py_0

  pyqt               conda-forge::pyqt-5.6.0-py36h13b7fb3_~ --> pkgs/main::pyqt-5.6.0-py36h22d08a2_6

  pyrsistent         conda-forge::pyrsistent-0.17.3-py36h8~ --> pkgs/main::pyrsistent-0.17.3-py36h7b6447c_0

  python-dateutil                               conda-forge --> pkgs/main

  pytz                conda-forge::pytz-2020.1-pyh9f0ad1d_0 --> pkgs/main::pytz-2020.1-py_0

  qtconsole          conda-forge::qtconsole-4.7.7-pyh9f0ad~ --> pkgs/main::qtconsole-4.7.7-py_0

  qtpy                                          conda-forge --> pkgs/main

  readline           conda-forge::readline-7.0-hf8c457e_10~ --> pkgs/main::readline-7.0-h7b6447c_5

  scikit-learn       conda-forge::scikit-learn-0.19.1-py36~ --> pkgs/main::scikit-learn-0.19.1-py36hedc7406_0

  scipy              conda-forge::scipy-1.1.0-py36_blas_op~ --> pkgs/main::scipy-1.1.0-py36hfa4b5c9_1

  send2trash         conda-forge/noarch::send2trash-1.5.0-~ --> pkgs/main/linux-64::send2trash-1.5.0-py36_0

  sip                conda-forge::sip-4.18.1-py36hf484d3e_~ --> pkgs/main::sip-4.18.1-py36hf484d3e_2

  six                  conda-forge::six-1.15.0-pyh9f0ad1d_0 --> pkgs/main::six-1.15.0-py_0

  termcolor          conda-forge/noarch::termcolor-1.1.0-p~ --> pkgs/main/linux-64::termcolor-1.1.0-py36_1

  terminado          conda-forge::terminado-0.9.1-py36h9f0~ --> pkgs/main::terminado-0.9.1-py36_0

  testpath                                      conda-forge --> pkgs/main

  tk                      conda-forge::tk-8.6.10-hed695b0_0 --> pkgs/main::tk-8.6.10-hbc83047_0

  tornado            conda-forge::tornado-6.0.4-py36h8c4c3~ --> pkgs/main::tornado-6.0.4-py36h7b6447c_1

  traitlets          conda-forge::traitlets-4.3.3-py36h9f0~ --> pkgs/main::traitlets-4.3.3-py36_0

  wcwidth            conda-forge::wcwidth-0.2.5-pyh9f0ad1d~ --> pkgs/main::wcwidth-0.2.5-py_0

  webencodings       conda-forge/noarch::webencodings-0.5.~ --> pkgs/main/linux-64::webencodings-0.5.1-py36_1

  werkzeug           conda-forge::werkzeug-1.0.1-pyh9f0ad1~ --> pkgs/main::werkzeug-1.0.1-py_0

  wheel              conda-forge::wheel-0.35.1-pyh9f0ad1d_0 --> pkgs/main::wheel-0.35.1-py_0

  widgetsnbextension conda-forge::widgetsnbextension-3.5.1~ --> pkgs/main::widgetsnbextension-3.5.1-py36_0

  xz                       conda-forge::xz-5.2.5-h516909a_1 --> pkgs/main::xz-5.2.5-h7b6447c_0

  yaml                   conda-forge::yaml-0.2.5-h516909a_0 --> pkgs/main::yaml-0.2.5-h7b6447c_0

  zlib               conda-forge::zlib-1.2.11-h516909a_1009 --> pkgs/main::zlib-1.2.11-h7b6447c_3

  zstd                   conda-forge::zstd-1.4.5-h6597ccf_2 --> pkgs/main::zstd-1.4.5-h9ceee32_0

Proceed ([y]/n)? y

Downloading and Extracting Packages

testpath-0.4.4       | 82 KB     | ################################################################################################ | 100% 

zstd-1.4.5           | 619 KB    | ################################################################################################ | 100% 

mkl-2018.0.3         | 126.9 MB  | ################################################################################################ | 100% 

grpcio-1.14.1        | 944 KB    | ################################################################################################ | 100% 

jupyterlab_pygments- | 8 KB      | ################################################################################################ | 100% 

readline-7.0         | 324 KB    | ################################################################################################ | 100% 

bleach-3.2.1         | 112 KB    | ################################################################################################ | 100% 

markupsafe-1.1.1     | 29 KB     | ################################################################################################ | 100% 

async_generator-1.10 | 39 KB     | ################################################################################################ | 100% 

python-dateutil-2.8. | 215 KB    | ################################################################################################ | 100% 

ipykernel-5.3.4      | 181 KB    | ################################################################################################ | 100% 

argon2-cffi-20.1.0   | 46 KB     | ################################################################################################ | 100% 

freetype-2.10.4      | 596 KB    | ################################################################################################ | 100% 

mistune-0.8.4        | 55 KB     | ################################################################################################ | 100% 

scikit-learn-0.19.1  | 3.9 MB    | ################################################################################################ | 100% 

traitlets-4.3.3      | 140 KB    | ################################################################################################ | 100% 

sip-4.18.1           | 261 KB    | ################################################################################################ | 100% 

pandoc-2.11          | 9.6 MB    | ################################################################################################ | 100% 

jupyterlab_launcher- | 23 KB     | ################################################################################################ | 100% 

kiwisolver-1.2.0     | 84 KB     | ################################################################################################ | 100% 

importlib_metadata-2 | 11 KB     | ################################################################################################ | 100% 

pexpect-4.8.0        | 82 KB     | ################################################################################################ | 100% 

nest-asyncio-1.4.1   | 10 KB     | ################################################################################################ | 100% 

keras-applications-1 | 45 KB     | ################################################################################################ | 100% 

zipp-3.3.1           | 12 KB     | ################################################################################################ | 100% 

libxml2-2.9.10       | 1.2 MB    | ################################################################################################ | 100% 

decorator-4.4.2      | 14 KB     | ################################################################################################ | 100% 

jedi-0.17.2          | 916 KB    | ################################################################################################ | 100% 

zeromq-4.3.3         | 500 KB    | ################################################################################################ | 100% 

defusedxml-0.6.0     | 23 KB     | ################################################################################################ | 100% 

setuptools-50.3.0    | 713 KB    | ################################################################################################ | 100% 

webencodings-0.5.1   | 19 KB     | ################################################################################################ | 100% 

ipython_genutils-0.2 | 39 KB     | ################################################################################################ | 100% 

lz4-c-1.9.2          | 175 KB    | ################################################################################################ | 100% 

pyzmq-19.0.2         | 434 KB    | ################################################################################################ | 100% 

pandocfilters-1.4.2  | 13 KB     | ################################################################################################ | 100% 

cycler-0.10.0        | 13 KB     | ################################################################################################ | 100% 

termcolor-1.1.0      | 8 KB      | ################################################################################################ | 100% 

mkl_random-1.0.1     | 324 KB    | ################################################################################################ | 100% 

protobuf-3.13.0.1    | 633 KB    | ################################################################################################ | 100% 

qtpy-1.9.0           | 38 KB     | ################################################################################################ | 100% 

prompt-toolkit-3.0.8 | 248 KB    | ################################################################################################ | 100% 

nbformat-5.0.8       | 88 KB     | ################################################################################################ | 100% 

markdown-3.3.2       | 125 KB    | ################################################################################################ | 100% 

scipy-1.1.0          | 13.2 MB   | ################################################################################################ | 100% 

h5py-2.10.0          | 901 KB    | ################################################################################################ | 100% 

expat-2.2.10         | 153 KB    | ################################################################################################ | 100% 

jupyter_core-4.6.3   | 71 KB     | ################################################################################################ | 100% 

libffi-3.2.1         | 48 KB     | ################################################################################################ | 100% 

ptyprocess-0.6.0     | 23 KB     | ################################################################################################ | 100% 

wheel-0.35.1         | 37 KB     | ################################################################################################ | 100% 

pip-20.2.4           | 1.8 MB    | ################################################################################################ | 100% 

nbconvert-6.0.7      | 480 KB    | ################################################################################################ | 100% 

libprotobuf-3.13.0.1 | 2.0 MB    | ################################################################################################ | 100% 

pyyaml-5.3.1         | 180 KB    | ################################################################################################ | 100% 

entrypoints-0.3      | 12 KB     | ################################################################################################ | 100% 

jupyter_console-6.2. | 26 KB     | ################################################################################################ | 100% 

pyqt-5.6.0           | 4.4 MB    | ################################################################################################ | 100% 

tornado-6.0.4        | 597 KB    | ################################################################################################ | 100% 

hdf5-1.10.6          | 3.7 MB    | ################################################################################################ | 100% 

attrs-20.2.0         | 42 KB     | ################################################################################################ | 100% 

tbb4py-2020.3        | 200 KB    | ################################################################################################ | 100% 

jsonschema-3.2.0     | 47 KB     | ################################################################################################ | 100% 

qtconsole-4.7.7      | 96 KB     | ################################################################################################ | 100% 

numpy-1.15.1         | 36 KB     | ################################################################################################ | 100% 

gstreamer-1.14.0     | 3.1 MB    | ################################################################################################ | 100% 

qt-5.6.3             | 36.4 MB   | ################################################################################################ | 100% 

mkl_fft-1.0.6        | 135 KB    | ################################################################################################ | 100% 

send2trash-1.5.0     | 16 KB     | ################################################################################################ | 100% 

pickleshare-0.7.5    | 13 KB     | ################################################################################################ | 100% 

widgetsnbextension-3 | 862 KB    | ################################################################################################ | 100% 

sqlite-3.33.0        | 1.1 MB    | ################################################################################################ | 100% 

ipywidgets-7.5.1     | 98 KB     | ################################################################################################ | 100% 

cffi-1.14.0          | 223 KB    | ################################################################################################ | 100% 

ipython-7.16.1       | 999 KB    | ################################################################################################ | 100% 

tbb-2020.3           | 1.1 MB    | ################################################################################################ | 100% 

glib-2.63.1          | 2.9 MB    | ################################################################################################ | 100% 

keras-preprocessing- | 44 KB     | ################################################################################################ | 100% 

absl-py-0.10.0       | 168 KB    | ################################################################################################ | 100% 

c-ares-1.16.1        | 108 KB    | ################################################################################################ | 100% 

pyrsistent-0.17.3    | 89 KB     | ################################################################################################ | 100% 

importlib-metadata-2 | 35 KB     | ################################################################################################ | 100% 

jupyter_client-6.1.7 | 77 KB     | ################################################################################################ | 100% 

astor-0.8.1          | 47 KB     | ################################################################################################ | 100% 

notebook-6.1.4       | 4.1 MB    | ################################################################################################ | 100% 

terminado-0.9.1      | 27 KB     | ################################################################################################ | 100% 

prompt_toolkit-3.0.8 | 12 KB     | ################################################################################################ | 100% 

numpy-base-1.15.1    | 3.4 MB    | ################################################################################################ | 100% 

gast-0.4.0           | 15 KB     | ################################################################################################ | 100% 

nbclient-0.5.1       | 58 KB     | ################################################################################################ | 100% 

pygments-2.7.1       | 671 KB    | ################################################################################################ | 100% 

intel-openmp-2019.4  | 729 KB    | ################################################################################################ | 100% 

dbus-1.13.18         | 504 KB    | ################################################################################################ | 100% 

Preparing transaction: done

Verifying transaction: done

Executing transaction: | Uninstalling jupyter-js-widgets jupyter-js-widgets/extension

Removing: /home/bojan/anaconda3/envs/my-env/share/jupyter/nbextensions/jupyter-js-widgets

done

Let's now install it from conda-forge channel:

(my-env) $ conda install -c conda-forge opencv

Collecting package metadata (current_repodata.json): done

Solving environment: failed with initial frozen solve. Retrying with flexible solve.

Solving environment: failed with repodata from current_repodata.json, will retry with next repodata source.

Collecting package metadata (repodata.json): done

Solving environment: failed with initial frozen solve. Retrying with flexible solve.

Solving environment: done

## Package Plan ##

  environment location: /home/bojan/anaconda3/envs/my-env

  added / updated specs:

    - opencv

The following packages will be downloaded:

    package                    |            build

    ---------------------------|-----------------

    giflib-5.2.1               |       h36c2ea0_2          77 KB  conda-forge

    gmp-6.2.0                  |       h58526e2_4         818 KB  conda-forge

    graphite2-1.3.13           |    h58526e2_1001         102 KB  conda-forge

    pixman-0.40.0              |       h36c2ea0_0         627 KB  conda-forge

    ------------------------------------------------------------

                                           Total:         1.6 MB

The following NEW packages will be INSTALLED:

  bzip2              conda-forge/linux-64::bzip2-1.0.8-h516909a_3

  cairo              pkgs/main/linux-64::cairo-1.14.12-h8948797_3

  ffmpeg             conda-forge/linux-64::ffmpeg-4.1.3-h167e202_0

  giflib             conda-forge/linux-64::giflib-5.2.1-h36c2ea0_2

  gmp                conda-forge/linux-64::gmp-6.2.0-h58526e2_4

  gnutls             conda-forge/linux-64::gnutls-3.6.13-h79a8f9a_0

  graphite2          conda-forge/linux-64::graphite2-1.3.13-h58526e2_1001

  harfbuzz           pkgs/main/linux-64::harfbuzz-2.4.0-hca77d97_0

  jasper             conda-forge/linux-64::jasper-1.900.1-h07fcdf6_1006

  lame               conda-forge/linux-64::lame-3.100-h14c3975_1001

  libblas            conda-forge/linux-64::libblas-3.8.0-8_h6e990d7_netlib

  libcblas           conda-forge/linux-64::libcblas-3.8.0-8_h6e990d7_netlib

  libiconv           conda-forge/linux-64::libiconv-1.16-h516909a_0

  liblapack          conda-forge/linux-64::liblapack-3.8.0-8_h6e990d7_netlib

  liblapacke         conda-forge/linux-64::liblapacke-3.8.0-8_h6e990d7_netlib

  libwebp            conda-forge/linux-64::libwebp-1.0.2-h56121f0_5

  nettle             conda-forge/linux-64::nettle-3.4.1-h1bed415_1002

  opencv             conda-forge/linux-64::opencv-4.1.0-py36h79d2e43_1

  openh264           conda-forge/linux-64::openh264-1.8.0-hdbcaa40_1000

  pixman             conda-forge/linux-64::pixman-0.40.0-h36c2ea0_0

  x264               conda-forge/linux-64::x264-1!152.20180806-h14c3975_0

The following packages will be SUPERSEDED by a higher-priority channel:

  ca-certificates    pkgs/main::ca-certificates-2020.10.14~ --> conda-forge::ca-certificates-2020.6.20-hecda079_0

  certifi            pkgs/main/noarch::certifi-2020.6.20-p~ --> conda-forge/linux-64::certifi-2020.6.20-py36h9880bd3_2

  h5py                pkgs/main::h5py-2.10.0-py36hd6299e0_1 --> conda-forge::h5py-2.9.0-nompi_py36hcafd542_1103

  hdf5                    pkgs/main::hdf5-1.10.6-hb1b8bf9_0 --> conda-forge::hdf5-1.10.4-nompi_h3c11f04_1106

  openssl              pkgs/main::openssl-1.0.2u-h7b6447c_0 --> conda-forge::openssl-1.0.2u-h516909a_0

Proceed ([y]/n)? y

Downloading and Extracting Packages

graphite2-1.3.13     | 102 KB    | ################################################################################################ | 100% 

gmp-6.2.0            | 818 KB    | ################################################################################################ | 100% 

pixman-0.40.0        | 627 KB    | ################################################################################################ | 100% 

giflib-5.2.1         | 77 KB     | ################################################################################################ | 100% 

Preparing transaction: done

Verifying transaction: done

Executing transaction: done

After this we have only this OpenCV package:

(my-env) $ conda list | grep opencv

opencv                    4.1.0            py36h79d2e43_1    conda-forge

 

NOTE: If we want to install specific version of the package it can be specified like here:

(my-env) $ conda install -c conda-forge opencv=4.1.0

Let's check details of GUI support in this build:

(my-env) $ python

Python 3.6.6 | packaged by conda-forge | (default, Oct 12 2018, 14:43:46) 

[GCC 7.3.0] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> import cv2

>>> cv2.getBuildInformation()

'\nGeneral configuration for OpenCV 4.1.0 =====================================\n  Version control:               90416df\n\n  Extra modules:\n    Location (extra):            /home/conda/feedstock_root/build_artifacts/opencv_1556233957555/work/opencv_contrib/modules\n    Version control (extra):     90416df\n\n  Platform:\n    Timestamp:                   2019-04-25T23:17:35Z\n    Host:                        Linux 4.15.0-1041-azure x86_64\n    GUI: \n    QT:                          YES (ver 5.6.2)\n      QT OpenGL support:         NO\n    GTK+:                        NO\n\n  Media I/O: \n    

>>> 

This now opens an image in its own window:

(my-env) $ python

Python 3.6.6 | packaged by conda-forge | (default, Oct 12 2018, 14:43:46) 

[GCC 7.3.0] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> import cv2

>>> import numpy as np

>>> cv2.imshow('darkness', np.zeros((100, 100)))

>>> cv2.waitKey()

82

>>> Killed

We can specify desired channel and version of the package in the environment yml file:

my_env_config.yml:

name: my_env

channels:

  - menpo

  - conda-forge

  - defaults

dependencies:

  ...

  - conda-forge::opencv=4.1.0 # required for Ubuntu. This cv2 package has Qt as GUI backend

  ...