Ubuntu running pip install gives error 'The following required packages can not be built: * freetype'

When performing pip install -r requirements.txt, I get the following error during the stage where it is installing matplotlib:

    REQUIRED DEPENDENCIES AND EXTENSIONS
                     numpy: yes [not found. pip may install it below.]
                  dateutil: yes [dateutil was not found. It is required for date
                            axis support. pip/easy_install may attempt to
                            install it after matplotlib.]
                   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 [pyparsing was not found. It is required for
                            mathtext support. pip/easy_install may attempt to
                            install it after matplotlib.]
                     pycxx: yes [Couldn't import.  Using local copy.]
                    libagg: yes [pkg-config information for 'libagg' could not
                            be found. Using local copy.]
                  freetype: no  [pkg-config information for 'freetype2' could
                            not be found.]

...

    The following required packages can not be built:

                        * freetype

Shouldn't pip install -r requirements.txt also install freetype? How should freetype be installed in Ubuntu 12.04 so it works with matplotlib?

No. pip will not install system-level dependencies. This means pip will not install RPM(s) ( Redhat based systems ) or DEB(s) ( Debian based systems ).

To install system dependencies you will need to use one of the following methods depending on your system.

Ubuntu/Debian:

    apt-get install libfreetype6-dev

To search for packages on Ubuntu/Debian based systems:

    apt-cache search <string>

e.g:

    apt-cache search freetype | grep dev

Redhat/CentOS/Fedora:

    yum -y install freetype-devel

To search for packages on Redhat/CentOS/Fedora based systems:

    yum search <string>

e.g:

    yum search freetype | grep devel

Mac OS X: ( viaHomebrew )

    brew install freetype

To search for packages on Mac OS X based systems:

    brew search <string>

e.g:

    brew search freetype

From: stackoverflow.com/q/20533426

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