Hi Stuart, I don't think what you are experiencing is an issue. Several components (i.e. functions) of `scikit-image` are implemented in Cython, and require it in order to be build and linked with Python API. "Binary" distributions of `scikit-image` (including the PyPi .whl-files) ship such components pre-built, so the requirements for running `scikit-image` and building it are different. You can take a look at the requirements for different usecases (building package, executing package, building gallery, etc) in our repository in https://github.com/scikit-image/scikit-image/tree/master/requirements . If you are only interested in installing `scikit-image`, I'd you recommend you to use the provided pre-built distributions available for the most popular architectures and operating systems: pip install --no-cache-dir scikit-image Regards, Egor On Fri, 27 Jul 2018 at 13:28, Stuart Mumford <stuart@cadair.com> wrote:

Hello,

I have just run into an error while trying to install scikit-image from the pip tarball on linux (as part of the SunPy test infrastructure). It seems that the PyPI tarball needs Cython to be installed:

 pip install --no-binary=:all: --no-cache-dir scikit-image Collecting scikit-image Downloading https://files.pythonhosted.org/packages/fc/20/d3e736493b16e9455ce8579722d644... (27.0MB) 100% |████████████████████████████████| 27.0MB 5.9MB/s Complete output from command python setup.py egg_info: Partial import of skimage during the build process. Traceback (most recent call last): File "/tmp/pip-install-ypyllick/scikit-image/skimage/_build.py", line 30, in cython from Cython import __version__ ModuleNotFoundError: No module named 'Cython'

During handling of the above exception, another exception occurred:

Traceback (most recent call last): File "<string>", line 1, in <module> File "/tmp/pip-install-ypyllick/scikit-image/setup.py", line 149, in <module> **extra File "/opt/miniconda/envs/clean/lib/python3.7/site-packages/numpy/distutils/core.py", line 135, in setup config = configuration() File "/tmp/pip-install-ypyllick/scikit-image/setup.py", line 70, in configuration config.add_subpackage('skimage') File "/opt/miniconda/envs/clean/lib/python3.7/site-packages/numpy/distutils/misc_util.py", line 1034, in add_subpackage caller_level = 2) File "/opt/miniconda/envs/clean/lib/python3.7/site-packages/numpy/distutils/misc_util.py", line 1003, in get_subpackage caller_level = caller_level + 1) File "/opt/miniconda/envs/clean/lib/python3.7/site-packages/numpy/distutils/misc_util.py", line 940, in _get_configuration_from_setup_py config = setup_module.configuration(*args) File "skimage/setup.py", line 14, in configuration config.add_subpackage('feature') File "/opt/miniconda/envs/clean/lib/python3.7/site-packages/numpy/distutils/misc_util.py", line 1034, in add_subpackage caller_level = 2) File "/opt/miniconda/envs/clean/lib/python3.7/site-packages/numpy/distutils/misc_util.py", line 1003, in get_subpackage caller_level = caller_level + 1) File "/opt/miniconda/envs/clean/lib/python3.7/site-packages/numpy/distutils/misc_util.py", line 940, in _get_configuration_from_setup_py config = setup_module.configuration(*args) File "skimage/feature/setup.py", line 22, in configuration cython(['_haar.pyx'], working_path=base_path) File "/tmp/pip-install-ypyllick/scikit-image/skimage/_build.py", line 42, in cython % CYTHON_VERSION) RuntimeError: Cython >= 0.23 is required to build scikit-image from git checkout Cython >= 0.23 not found; falling back to pre-built geometry.c Cython >= 0.23 not found; falling back to pre-built transform.c Cython >= 0.23 not found; falling back to pre-built interpolation.c Cython >= 0.23 not found; falling back to pre-built _draw.c Cython >= 0.23 not found; falling back to pre-built corner_cy.c Cython >= 0.23 not found; falling back to pre-built censure_cy.c Cython >= 0.23 not found; falling back to pre-built orb_cy.c Cython >= 0.23 not found; falling back to pre-built brief_cy.c Cython >= 0.23 not found; falling back to pre-built _texture.c Cython >= 0.23 not found; falling back to pre-built _hessian_det_appx.c Cython >= 0.23 not found; falling back to pre-built _hoghistogram.c

---------------------------------------- Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-install-ypyllick/scikit-image/

I don't know if this is a bug in the tarball / setup machinery or if it's some silly mistake I am making.

Thanks for any help,

Stuart _______________________________________________ scikit-image mailing list scikit-image@python.org https://mail.python.org/mailman/listinfo/scikit-image