python list of lists contain substring

April 13, 2022

I have the list_of_lists and I need to get the string that contains ‘height’ in the sublists and if there is no height at all I need to get ‘nvt’ for the whole sublist.

I have tried the following:

list_of_lists = [['width=9','length=3'],['width=6','length=4','height=4']]

_lists = []

for list in list_of_lists:
    list1 = []
    for st in list:
        if ("height" ) in st:
            list1.append(st)
        else:
            list1.append('nvt')
        _lists.append(list1)

OUT = _lists

the result I need to have is :

_lists = ['nvt', 'height=4']

what I’m getting is:

_lists =  [['nvt','nvt'],['nvt','nvt','height=4']]

>Solution :

This is a good case for implementing a for/else construct as follows:

list_of_lists = [['width=9','length=3'],['width=6','length=4','height=4']]

result = []

for e in list_of_lists:
    for ss in e:
        if ss.startswith('height'):
            result.append(ss)
            break
    else:
        result.append('nvt')
        
print(result)

Output:

['nvt', 'height=4']

Note:

This could probably be done with a list comprehension but I think this is more obvious and probably has no significant difference in terms of performance