如何通过在 python 的列表中仅给出该元素的特定部分来查找列表中元素的索引

Question

a=["cat on the wall" ,"dog on the table","tea in the cup"]
b= "dog"
for i in a:
  if b in i:
    print(a.index(i))

The output prints the index of the element where is "dog" is present

can this be done in using any inbuilt function, variable b contains only a part of the element in the list.

Answer 1

Looks like you need enumerate

Ex:

a=["cat on the wall" ,"dog on the table","tea in the cup"]
b= "dog"
for idx, v in enumerate(a):
    if b in v:
        print(idx) #-->1

Answer 2

a=["cat on the wall" ,"dog on the table","tea in the cup"]
b= "dog"

for z in a:
    if b in z:
        print(a.index(z))

Answer 3

There's no direct way to do it. Other functions (eg. sorted ) accept a key that they use to compare elements. But index depends on equality. So, you have two choices

• override the equality operator. not a good idea in your case, since you have simple strings.
• rewrite you loop, using a regular expression

import re

for word in a:
    position = re.search(b, word)

    if position is not None:
        start_index = position.span()[0]
        print(start_index)

Answer 4

As blue_note mentioned there is no direct way for this. You can simplify usingList Comprehension . Like,

a = ["cat on the wall", "dog on the table", "tea in the cup"]
b = "dog"
print ([idx for idx, itm in enumerate(a) if b in itm])