Faster way to subtract columns and update row values? Faster way to subtract columns and update row values? colSet1 = list(range(20)) colSet2 = list(range(21,40)) colSet3 = list(range(41,60)) for col1 in colSet1: for col2 in colSet2: for col3 in colSet3: df[col1+col2+col3+"_newcol"] = df[col1+col2+col3]-df[col1] I tried rsub but it seems to give wrong results, not sure, if i implemented it correctly. What is the correct way to use rsub in this case, If that is the fastest way?