title: How to make an N by N matrix using python in which value for each a(i,j) is known?
body: <p>data is given like this in a text file:</p>
  <p>A B 1 <br />
  B C -1 <br />
  A C 1 <br />
  B D 1  <br />
  D A -1 <br />
  C D 1</p>
  <p>and the matrix has to be like: <br />
  \   A  B  C  D <br />
  A    0  1   1 -1 <br />
  B    1  0  -1  1<br />
  C    1 -1   0  1 <br />
  D   -1  1   1  0</p>