CODEWITHSUNDEEP
pythonnested-lists
beginnerlearner456
beginnerlearner456

Reputation: 45

How to search a list within a list

I am trying to search through lists within a list to find and change one of the items.

I want to be able to search the 0th and 1st item in the lists, and if they match my criteria I want to change/update the 2nd item.

I understand you can search using enumerate but am struggling to understand/write the coding for this.

myList = [['blue', 'house', 'go', 'no'],['yellow', 'mansion', 'stop', 'yes']]

I would like to be able to search the list for the 0th element being 'blue' and the 1st element being 'house', and then change the 2nd element to 'stop.

Any ideas?

Upvotes: 1

Views: 93

Answers (4)

Ajax1234
Ajax1234

Reputation: 71451

You can use unpacking for a cleaner solution:

myList = [['blue', 'house', 'go', 'no'],['yellow', 'mansion', 'stop', 'yes']]
result = [[*a, 'stop' if a == ['blue', 'house'] else b, c] for *a, b, c in myList]

Output:

[['blue', 'house', 'stop', 'no'], ['yellow', 'mansion', 'stop', 'yes']]

Upvotes: 0

Sash Sinha
Sash Sinha

Reputation: 22275

Using a for loop and checking both that the first element of the current inner list equals blue and the second element equals house explicitly might be the easiest to understand if you haven't learnt list slicing yet:

my_lists = [['blue', 'house', 'go', 'no'],['yellow', 'mansion', 'stop', 'yes']]
for inner_list in my_lists:
    if inner_list[0] == 'blue' and inner_list[1] == 'house':
        inner_list[2] = 'stop'
print(my_lists)

Output:

[['blue', 'house', 'stop', 'no'], ['yellow', 'mansion', 'stop', 'yes']]

Upvotes: 1

Ami Tavory
Ami Tavory

Reputation: 76297

One-liner using list comprehension

>>> [e if e[: 2] != ['blue', 'house'] else (e[: 2] + ['stop'] + e[3: ]) for e in myList]
[['blue', 'house', 'stop', 'no'], ['yellow', 'mansion', 'stop', 'yes']]

Upvotes: 1

Deepstop
Deepstop

Reputation: 3807

You can slice myList so you can do both comparisons without using and

myList = [['blue', 'house', 'go', 'no'],['yellow', 'mansion', 'stop', 'yes']]
for m in myList:
    if m[:2] == ['blue', 'house']:
        m[2] = 'stop'
print(myList)

[['blue', 'house', 'stop', 'no'], ['yellow', 'mansion', 'stop', 'yes']]

Upvotes: 1

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