With the following lists: A=['asd','qwe','wer'] B=[1,2,3] C=['ttt', 'ttt', 'ttt'] D=[1,2,5] E=[0,30,0] The desired output is: F=['asd',1,'ttt',1,0,'qwe',2,'ttt',2,30,'wer',3,'ttt',5,0] My attempted solution: F=[] for i in E: F.append(A[E.index(i)]) F.append(B[E.index(i)]) F.append(C[E.index(i)]) F.append(D[E.index(i)]) F.append(E[E.index(i)]) print(F) However the output here is: ['asd', 1, 'ttt', 1, 0, 'qwe', 2, 'ttt', 2, 30, 'asd', 1, 'ttt', 1, 0] You can see that 'asd' repeats and I'm not sure why. Continue reading...