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

I am new to python. Recently I got a project written by python and it requires some installation. I run below command to install but got an error.

# pip install requirements.txt 
Collecting requirements.txt
  Could not find a version that satisfies the requirement requirements.txt (from versions: )
No matching distribution found for requirements.txt

I searched on google and found this link http://stackoverflow.com/questions/28167987/python-pip-trouble-installing-from-requirements-txt but I don't quite understand what the solution in that post.

Below is my requirements.txt file:

# cat requirements.txt 
ordereddict==1.1
argparse==1.2.1
python-dateutil==2.2
matplotlib==1.3.1
nose==1.3.0
numpy==1.8.0
pymongo==3.3.0
psutil>=2.0

Is there a easy way to install all required dependencies in this python project?

EDIT1

Below is the output from pip3 install -r requirements.txt.

# pip3 install -r requirements.txt 
Requirement already satisfied: ordereddict==1.1 in /usr/local/lib/python3.5/dist-packages (from -r requirements.txt (line 1))
Collecting argparse==1.2.1 (from -r requirements.txt (line 2))
  Using cached argparse-1.2.1.tar.gz
Collecting python-dateutil==2.2 (from -r requirements.txt (line 3))
  Using cached python-dateutil-2.2.tar.gz
Collecting matplotlib==1.3.1 (from -r requirements.txt (line 4))
  Using cached matplotlib-1.3.1.tar.gz
    Complete output from command python setup.py egg_info:
    ============================================================================
    Edit setup.cfg to change the build options

    BUILDING MATPLOTLIB
                matplotlib: yes [1.3.1]
                    python: yes [3.5.2 (default, Nov 17 2016, 17:05:23)  [GCC
                            5.4.0 20160609]]
                  platform: yes [linux]

    REQUIRED DEPENDENCIES AND EXTENSIONS
                     numpy: yes [version 1.11.3]
                  dateutil: yes [using dateutil version 2.6.0]
                   tornado: yes [tornado was not found. It is required for the
                            WebAgg backend. pip/easy_install may attempt to
                            install it after matplotlib.]
                 pyparsing: yes [using pyparsing version 2.1.10]
                     pycxx: yes [Official versions of PyCXX are not compatible
                            with Python 3.x.  Using local copy]
                    libagg: yes [pkg-config information for 'libagg' could not
                            be found. Using local copy.]
                  freetype: no  [The C/C++ header for freetype2 (ft2build.h)
                            could not be found.  You may need to install the
                            development package.]
                       png: yes [pkg-config information for 'libpng' could not
                            be found. Using unknown version.]

    OPTIONAL SUBPACKAGES
               sample_data: yes [installing]
                  toolkits: yes [installing]
                     tests: yes [using nose version 1.3.7]

    OPTIONAL BACKEND EXTENSIONS
                    macosx: no  [Mac OS-X only]
                    qt4agg: no  [PyQt4 not found]
                   gtk3agg: no  [gtk3agg backend does not work on Python 3]
                 gtk3cairo: no  [Requires cairo to be installed.]
                    gtkagg: no  [Requires pygtk]
                     tkagg: no  [TKAgg requires Tkinter.]
                     wxagg: no  [requires wxPython]
                       gtk: no  [Requires pygtk]
                       agg: yes [installing]
                     cairo: no  [cairo not found]
                 windowing: no  [Microsoft Windows only]

    OPTIONAL LATEX DEPENDENCIES
                    dvipng: no
               ghostscript: no
                     latex: no
                   pdftops: no

    ============================================================================
                            * The following required packages can not be built:
                            * freetype

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-don4ne_2/matplotlib/

I have already installed libfreetype6-dev but the pip command still reports missing this dependency.

# apt-get install libfreetype6-dev
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libfreetype6-dev is already the newest version (2.6.1-0.1ubuntu2).
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.

This question is related to python pip requirements.txt

The answer is


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

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


(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


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