title: Pip install scikit-image using locally installed dependency
body: <p>I'm trying to install scikit-image on a server that I don't have admin privileges on. Scikit-image requires Cython >= 0.23 as a dependency, but the server has Cython 0.21 installed globally.</p>
  
  <pre><code>$ which Cython
  /opt/apps/software/MPI/GCC/4.8.3/OpenMPI/1.8.8/Python/2.7.9/bin/cython
  
  $ cython --version
  Cython version 0.21.2
  </code></pre>
  
  <p>I can install Cython 0.25.2 locally into a .pip folder for my project (following the advice <a href="https://www.zoomeranalytics.com/blog/pip-install-t" rel="nofollow noreferrer">here</a>):</p>
  
  <pre><code>$ pip install Cython -t .pip
  $ python ./.pip/cython.py --version
  Cython version 0.25.2
  </code></pre>
  
  <p>I've added <code>./.pip</code> to the beginning of my PYTHONPATH, but when I try to install scikit-image I get</p>
  
  <pre><code>$ pip install --user scikit-image
  ...
  RuntimeError: Cython &gt;= 0.23 needed to build scikit-image
  </code></pre>
  
  <p>How can I tell the pip installation to use the version of Cython sitting in <code>my_project/.pip</code>?</p>