How to use requirements.txt to install all dependencies in a python project

If you are using Linux OS:

1. Remove matplotlib==1.3.1 from requirements.txt
2. Try to install with sudo apt-get install python-matplotlib
3. Run pip install -r requirements.txt (Python 2), or pip3 install -r requirements.txt (Python 3)
4. pip freeze > requirements.txt

If you are using Windows OS:

1. python -m pip install -U pip setuptools
2. python -m pip install matplotlib

pip install -r requirements.txt for python 2.x

pip3 install -r requirements.txt for python 3.x (in case multiple versions are installed)

python -m pip install -r requirements.txt

Referece: How to install packages using pip according to the requirements.txt file from a local directory?

(Taken from my comment)

pip won't handle system level dependencies. You'll have to apt-get install libfreetype6-dev before continuing. (It even says so right in your output. Try skimming over it for such errors next time, usually build outputs are very detailed)

Python 3:

pip3 install -r requirements.txt

Python 2:

pip install -r requirements.txt

To get all the dependencies for the virtual environment or for the whole system:

pip freeze

To push all the dependencies to the requirements.txt (Linux):

pip freeze > requirements.txt