How to access the sub-list number from main list in Python?-CodePudding

I have a list with sub-lists: and I want to have the index from the sub-list where on the 0 place a name is stored: So in the following list I want to find the index of sub-list where 'Kolom3' is in

[['Kolom1', 'Tekst'], ['Kolom2', 'Tekst'], ['Kolom3', 'Tekst']]

so it must something do with list.index('Kolom3') and must return 3 and preferably not a for loop

CodePudding user response：

You can do that with zip though the output is 2 as Python uses 0 indexing:

list(list(zip(*lst))[0]).index('Kolom3')

Output:

CodePudding user response：

Considering the list to be as:

A = [['Kolom1', 'Tekst'], ['Kolom2', 'Tekst'], ['Kolom3', 'Tekst']]

Method 1:

This method uses a traditional for loop to figure out the index

for i, val in enumerate(A, 1):
    if "Kolom3" in val:
        print(f"Kolom3 is in position {i}")

Method 2:

This method directly references ["Kolom3", 'Tekst'].
The caveat here, is - what about duplicates? What if the second element is changed from Tekst to something else?

print(A.index(["Kolom3", 'Tekst'])   1)

Method 3:

This method uses list comprehension.

index = [i 1 for i, val in enumerate(A) if "Kolom3" in val]
print(index)

CodePudding user response：

You can use itertools.dropwhile:

>>> import itertools
>>> L = [['Kolom1', 'Tekst'], ['Kolom2', 'Tekst'], ['Kolom3', 'Tekst']]
>>> dw = itertools.dropwhile(lambda i: L[i][0] != 'Kolom3', range(len(L)))
>>> ind = next(dw)   1
>>> ind
3

Basically go over the range of indices and return the first index whose value verifies the condition.