列表清单，如何在每个列表中使用特定数字进行计算？

Question

I have a function:

def readCSVfile(str1):

This function takes a CSV file that the user chooses and reads it. Each file contains a list of list that looks like this:

[[1, 1, 2.2, 1.3, 9.6], [1, 2, 2.1, 2.2, 7.6], [1, 3, 2.7, 1.5, 2.2], [2, 1, 3.0, 4.5, 1.5], [2, 2, 3.1, 3.1, 4.0], [2, 3, 2.5, 2.8, 3.0], [3, 1, 1.9, 1.8, 4.5], [3, 2, 1.1, 0.5, 2.3], [3, 3, 3.5, 2.0, 7.5], [4, 1, 2.9, 2.7, 3.2], [4, 2, 4.5, 4.8, 6.5], [4, 3, 1.2, 1.8, 2.7]]

Now, after the user have chosen a file the job is to make the program print out some calculations from each list made by my program but i am stuck. Say for example that i want to multiply the third and the fourth number in each list, how would i specify that?

Trying to do something like

readCSVfile(str1)[2]

Don't work. I have googled like crazy

Answer 1

through map and a lambda as one way:

li = [[1, 1, 2.2, 1.3, 9.6], [1, 2, 2.1, 2.2, 7.6], [1, 3, 2.7, 1.5, 2.2], [2, 1, 3.0, 4.5, 1.5], [2, 2, 3.1, 3.1, 4.0], [2, 3, 2.5, 2.8, 3.0], [3, 1, 1.9, 1.8, 4.5], [3, 2, 1.1, 0.5, 2.3], [3, 3, 3.5, 2.0, 7.5], [4, 1, 2.9, 2.7, 3.2], [4, 2, 4.5, 4.8, 6.5], [4, 3, 1.2, 1.8, 2.7]]

for el in map(lambda x: [x[0], x[1], round(x[2] * x[3],2),x[4]],li):
    print(el)

[1, 1, 2.86, 9.6]
[1, 2, 4.62, 7.6]
[1, 3, 4.05, 2.2]
[2, 1, 13.5, 1.5]
[2, 2, 9.61, 4.0]
[2, 3, 7.0, 3.0]
[3, 1, 3.42, 4.5]
[3, 2, 0.55, 2.3]
[3, 3, 7.0, 7.5]
[4, 1, 7.83, 3.2]
[4, 2, 21.6, 6.5]
[4, 3, 2.16, 2.7]

Answer 2

lst = [ [1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5]]

for x in range(len(lst)):
    print(lst[x][2] * lst[x][3])