To check if list of string and lists is empty

Question

how to check if this list is empty?

l = ['',['']]

I tried solutions from how to find if nested lists are empty. but none of them worked.

def isListEmpty(inList):
    if isinstance(inList, list): # Is a list
         return all( map(isListEmpty, inList) )
    return False # Not a list

Check if its [length](https://docs.python.org/3/library/functions.html#len) is zero? — Some programmer dude, Feb 14 '19 at 16:47
@Someprogrammerdude, I'm pretty sure OP means it as empty string though there is a space like you say. — Austin, Feb 14 '19 at 16:49
why don't you [flatten the nested list](https://stackoverflow.com/a/953097/5858851) and check each element? — pault, Feb 14 '19 at 17:01

blhsing · Accepted Answer · 2019-02-14T17:13:35.873

1

You should check if the list is falsy/empty first before recursively checking the list items. You can also avoid explicitly returning True or False by using the and and or operators:

def isListEmpty(inList):
    return inList == '' or isinstance(inList, list) and (not inList or all(map(isListEmpty, inList)))

Demo: https://repl.it/repls/AccurateSmallOutcome

edited Feb 14 '19 at 17:13

answered Feb 14 '19 at 16:56

blhsing

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returns false for everything – Miffy Feb 14 '19 at 17:02
It returns `True` for `[[[]]]` for example. – blhsing Feb 14 '19 at 17:03
true but that is not the list I want to check for – Miffy Feb 14 '19 at 17:05
So you consider a list with an empty string empty? – blhsing Feb 14 '19 at 17:06
In that case I've updated my answer accordingly. Please check it out. – blhsing Feb 14 '19 at 17:08

score 0 · Answer 2 · answered Feb 14 '19 at 16:52

0

For lists that actually are empty, the function should simply return True.

def isListEmpty(inList):
    if isinstance(inList, list): # Is a list
        if len(inList) == 0:
            return True
        else:
            return all(map(isListEmpty, inList))
    return False # Not a list

answered Feb 14 '19 at 16:52

John Gordon

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It works for me. Can you provide a sample list that fails? – John Gordon Feb 14 '19 at 16:58
I added it in question itself – Miffy Feb 14 '19 at 16:59
That list contains a string, and your sample code explicitly returns non-empty for any data type that is not a list. If that is not your desired behavior, you chould make that clear. – John Gordon Feb 14 '19 at 18:06
yes its a list of (empty string and list of empty string) – Miffy Feb 15 '19 at 03:33

score 0 · Answer 3 · answered Feb 14 '19 at 17:10

0

l is not empty in fact. But in this case this code should work:

l = ['',['']]
def isListEmpty(inList):
    for char in inList:   
        if char == '' or ['']:
            return True
        else:
            return False
            break

print(isListEmpty(l))

answered Feb 14 '19 at 17:10

Heyran.rs

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What about for deeper lists like `['',['',['']]]` ? That is why other people have taken a recursive approach, because it can be infinitely deep – Adam Dadvar Feb 14 '19 at 17:26

Sunitha · Answer 4 · 2019-02-14T22:25:20.247

You can use a simple recursive approach with any. Using any would make sure that the recursively search ends as soon as a non empty item is found

>>> def is_non_empty_list (l):
...     return any(is_non_empty_list(e) if isinstance(e, list) else e for e in l)
... 
>>> def is_empty_list (l):
...     return not is_non_empty_list(l)
... 
>>> is_empty_list(['', ['']])
True
>>> is_empty_list(['', ['a']])
False
>>>

score -1 · Answer 5 · answered Feb 14 '19 at 16:51

-1

Try This

l = [' ',[ ]]
def isListEmpty(thisList):
  for el in thisList:
    if (len(el)==0 and type(el)==list):
      print('empty') # Or whatever you want to do if you encounter an empty list

isListEmpty(l)

If you face any problems comment below

answered Feb 14 '19 at 16:51

anand_v.singh

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To check if list of string and lists is empty

5 Answers5