pip install numpy ● Browse PyPI ● Look for wheel with a matching platform tag ● If one is found, download and install ● If no match is found, download and build from source
pip wheel ● pip wheel numpy ● numpy-1.15.1-cp35-cp35m-linux_armv7l.whl ● That, but for all packages ● 175,000 packages ● That, but for all versions of all packages ● 1,200,000 package versions ● That, but for Python 3.4 and 3.5...
Using piwheels ● Raspbian Stretch is pre-confgured to use piwheels.org as an additional index to PyPI ● Users get platform wheels without knowing it’s there ● Tutorials that say "warning: this step will take ages" are now wrong
piwheels usage stats ● 940,000 wheels ● 400-500k downloads per month ● Total of 23 years of build time saved in 10 months ● See piwheels.org for more info