Pandas Crosstab With Own Function

I have a function which takes two inputs and returns a float e.g. my_func('A', 'B') = 0.5. I have a list of possible inputs: x = ['A', 'B', 'C', 'D', 'E', 'F']. I want to produce

Solution 1:

Option 1 brute force

xt = pd.DataFrame(index=x, columns=x)

foriin x:
    forjin x:
        xt.set_value(i, j, my_func(i, j))

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Demo

defmy_func(i,j):returnord(i)*ord(j)x= ['A', 'B', 'C', 'D', 'E', 'F']

xt=pd.DataFrame(index=x,columns=x)for i in x:for j in x:xt.set_value(i,j,my_func(i,j))xtABCDEFA4225  4290  4355  4420  4485  4550B4290  4356  4422  4488  4554  4620C4355  4422  4489  4556  4623  4690D4420  4488  4556  4624  4692  4760E4485  4554  4623  4692  4761  4830F4550  4620  4690  4760  4830  4900

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Option 2

idx=pd.MultiIndex.from_product([x,x])pd.Series(idx.map(lambdax:my_func(*x)),idx).unstack()ABCDEFA4225  4290  4355  4420  4485  4550B4290  4356  4422  4488  4554  4620C4355  4422  4489  4556  4623  4690D4420  4488  4556  4624  4692  4760E4485  4554  4623  4692  4761  4830F4550  4620  4690  4760  4830  4900

Solution 2:

considering the brute force method, it is recommended to use the .loc method, i.e.

for i in x:
    for j in x:
        xt.loc[i,j] = my_func(i,j)

instead of:

for i in x:
    for j in x:
        xt.set_value(i, j, my_func(i, j))

because set_value is deprecated and will be removed in a future release. Also, .at[] or .iat[] acessors may be used.