如何在列表列表中获取外部列表元素的索引？

Question

I have a list:

mylist = [[0, [0]], [2, [1]], [3, [4]], [4, [1, 4]]]

I want to get the index of the element of the outer list given the element.

I have tried this, but this only fetches me the outer elements of the list.

get_index = [outer for outer, inner in mylist]

I want something like this:

Input: 2
Output: 1

Input: 4
Output: 3

Answer 1

You could use a dictionary comprehension with enumerate to easily look up the index from the first values:

d = {i[0]:ix for ix, i in enumerate(mylist)}
# {0: 0, 2: 1, 3: 2, 4: 3}

---

d[2]
# 1

d[4]
# 3

Answer 2

A function matching the desired input/output behavior:

def loc( x, ml ):
    return [a for a,b in ml].index(x)

Answer 3

You can also create a function to which you pass an Input and get the corresponding index as output

def get_index(inp):
    idx = [i for i, j in enumerate(mylist) if inp==j[0]]
    return idx[0]

inp = 2
get_index(inp)
# 1

inp = 4
get_index(inp)
# 3