All possible combinations of columns in dataframe -pandas/python

Question

I'm trying to take one dataframe and create another, with all possible combinations of the columns and the difference between the corresponding values, i.e on 11-apr column AB should be (B-A)= 0 etc.

e.g, starting with

        Dt              A           B           C          D
        11-apr          1           1           1          1
        10-apr          2           3           1          2

how do I get a new frame that looks like this:

I have come across the below post, but have not been able to transpose this to work for columns.

Aggregate all dataframe row pair combinations using pandas

Answer 1

You can use:

from itertools import combinations
df = df.set_index('Dt')

cc = list(combinations(df.columns,2))
df = pd.concat([df[c[1]].sub(df[c[0]]) for c in cc], axis=1, keys=cc)
df.columns = df.columns.map(''.join)
print (df)
        AB  AC  AD  BC  BD  CD
Dt                            
11-apr   0   0   0   0   0   0
10-apr   1  -1   0  -2  -1   1