Question

How to find the index of all occurrences of an element in a nested list with Python

Answer 1

nestedlist = [[1, 2, 3], [1, 5], [6, 1, 8, 9, 10], [9, 27, 1, 85], [1]]

for sub_list in nestedlist:
    if 1 in sub_list:
        print((nestedlist.index(sub_list),sub_list.index(1)))




'''
run:

(0, 0)
(1, 0)
(2, 1)
(3, 2)
(4, 0)

'''

 

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Answer 2

nestedlist = [[1, 2, 3], [1, 5], [6, 1, 8, 9, 10], [9, 27, 1, 85], [1]]

result = [(index1,index2) for (index1,sub_list) in enumerate(nestedlist) 
        for (index2,element) in enumerate(sub_list) if element==1]
        
print(result)


'''
run:

[(0, 0), (1, 0), (2, 1), (3, 2), (4, 0)]

'''

 

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