Perform An Operation On All Pairs Of Rows In A Column

Assume the following DataFrame: id A 1 0 2 10 3 200 4 3000 I would like to make a calculation betweeen all rows to all other rows. For example, if the calcul

Solution 1:

IIUC itertools

importitertoolss=list(itertools.combinations(df.index,2))pd.Series([df.A.loc[x[1]]-df.A.loc[x[0]]forxins])Out[495]:01012002300031904299052800dtype:int64

Update

s=list(itertools.combinations(df.index,2))pd.DataFrame([x+(df.A.loc[x[1]]-df.A.loc[x[0]],)forxins])Out[518]:01200110102200203300031219041329905232800

Solution 2:

Use broadcasted subtraction, then np.tril_indices to extract the lower diagonal (positive values).

# <= 0.23 # u = df['A'].values# 0.24+u=df['A'].to_numpy()u2=(u[:,None]-u)pd.Series(u2[np.tril_indices_from(u2,k=-1)])01012002190330004299052800dtype:int64

Or, use subtract.outer to avoid the conversion to array beforehand.

u2 = np.subtract.outer(*[df.A]*2)
pd.Series(u2[np.tril_indices_from(u2, k=-1)])

If you need the index as well, use

idx=np.tril_indices_from(u2,k=-1)pd.DataFrame({'val':u2[np.tril_indices_from(u2,k=-1)],'row':idx[0],'col':idx[1]})valrowcol0101012002021902133000    3042990    3152800    32