pip install with requirements.txt

pip install.py

pip freeze > requirements.txt
pip install -r requirements.txt

###### Requirements without Version Specifiers ######
nose

###### Requirements with Version Specifiers ######
docopt == 0.6.1             # Version Matching. Must be version 0.6.1
keyring >= 4.1.1            # Minimum version 4.1.1
coverage != 3.5             # Version Exclusion. Anything except version 3.5
Mopidy-Dirble ~= 1.1        # Compatible release. Same as >= 1.1, == 1.*

pip uninstall -r requirements.txt -y

pip check                   #check for broken dependencies
python -m pip cache purge   #remove all cached install

#https://stackoverflow.com/questions/11248073/how-do-i-remove-all-packages-installed-by-pip?page=1&tab=modifieddesc#tab-top
pip freeze > unins ; pip uninstall -y -r unins ; del unins  #remove all packages