CODEWITHSUNDEEP
pythonfor-loopcomparenested-lists
Ellira
Ellira

Reputation: 15

How to compare the index of 2 sublists' elements from a list of lists

I want to compare the first element from a sublist (Index [0]) to the same element from the sublist right before it. if it's not equal, I want to append a new element to the sublist that would be 0. if they are equal, i want to append the result of the sum of two second elements (ex: 12+12 = 24)

I dont know how to reference the data from the sublist before the one I examine in my loop to achieve the comparison because I just get some 0 appended.I'm pretty sure it's the way I did my referencing of the previous index that is wrong.

list = [['1046', '10'], ['1047','12'], ['1047','12']]

for sublists in list:

    if sublists[1] !=  sublists[1 - 1]:
        sublists.append(0)

    else:
        velocity = float(sublists[2]) + float(sublists[2 - 1])
        sublists.append(velocity)

and the resulting list is :

R_list = [['1046', '10', 0], ['1047', '12', 0], ['1047', '12', 0]]

While I wanted:

R_list = [['1046', '10', 0], ['1047', '12', 0], ['1047', '12', 24]]

Upvotes: 1

Views: 291

Answers (1)

IoaTzimas
IoaTzimas

Reputation: 10624

Your indexing is not correct in general. Try something like the following:

for i in range(1,len(R_list)):
    if R_list[i][0]!=R_list[i-1][0]:
        R_list[i].append(0)
    else:
        R_list[i].append(int(R_list[i][1])+int(R_list[i-1][1]))

For

R_list = [['1046', '10', 0], ['1047', '12', 0], ['1047', '12', 0]]

the above gives:

[['1046', '10', 0], ['1047', '12', 0, 0], ['1047', '12', 0, 24]]

Upvotes: 1

Related Questions