Creating boolean matrix from one column with pandas

Question

I have been searching for an answer but I don't know what to search for so I'll ask here instead. I'm a beginner python and pandas enthusiast.

I have a dataset where i would like to produce a matrix from a column. The matrix should have the value of 1 if the value in the column and its transposed state is equal and 0 if its not.

input:

  id x1
   A  1
   B  3
   C  1
   D  5

output:

  A  B  C  D

A 1  0  1  0

B 0  1  0  0

C 1  0  1  0

D 0  0  0  1

I would like to do this for six different columns and add the resulting matrixes into one matrix where the values range from 0-6 instead of just 0-1.

Answer 1

Partly because there's as of yet no convenient cartesian join (whistles and looks away), I tend to drop down to numpy level and use broadcasting when I need to do things like this. IOW, because we can do things like this

>>> df.x1.values - df.x1.values[:,None]
array([[ 0,  2,  0,  4],
       [-2,  0, -2,  2],
       [ 0,  2,  0,  4],
       [-4, -2, -4,  0]])

We can do

>>> pdf = pd.DataFrame(index=df.id.values, columns=df.id.values, 
                       data=(df.x1.values == df.x1.values[:,None]).astype(int))
>>> pdf
   A  B  C  D
A  1  0  1  0
B  0  1  0  0
C  1  0  1  0
D  0  0  0  1