Checking for lists of empty values

Question

What is the most effective way to check if a list contains only empty values (not if a list is empty, but a list of empty elements)? I am using the famously pythonic implicit booleaness method in a for loop:

def checkEmpty(lst):
    for element in lst:
        if element:
            return False
            break
    else:
        return True

Anything better around?

Silas Ray · Accepted Answer · 2012-08-30 15:52:25Z

16

if not any(lst):
    # ...

Should work. any() returns True if any element of the iterable it is passed evaluates True. Equivalent to:

def my_any(iterable):
    for i in iterable:
        if i:
            return True
    return False

edited Aug 30, 2012 at 15:52

answered Aug 30, 2012 at 15:45

Silas Ray

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2 Comments

Dr. Jan-Philip Gehrcke Over a year ago

Seems to be the most elegant approach :-)

squiguy Over a year ago

I agree, this is nice and clean.

João Silva · Accepted Answer · 2012-08-30 15:45:29Z

3

len([i for i in lst if i]) == 0

answered Aug 30, 2012 at 15:45

João Silva

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Comments

Steven Rumbalski · Accepted Answer · 2012-08-30 15:57:07Z

2

Using all:

   if all(item is not None for i in list):
      return True
    else:
      return False

edited Aug 30, 2012 at 15:57

Steven Rumbalski

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answered Aug 30, 2012 at 15:47

squiguy

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4 Comments

Steven Rumbalski Over a year ago

I think all's brother any feels slighted.

squiguy Over a year ago

@StevenRumbalski I like the shorter approach using any, but I thought I would throw in my two cents for an alternate idea.

Steven Rumbalski Over a year ago

Depending on the OP's definition of "empty", not bool(item) may be better than item is not None.

squiguy Over a year ago

@StevenRumbalski Thanks for the edit, you can change whatever you find to be suitable.

Dr. Jan-Philip Gehrcke · Accepted Answer · 2012-08-30 15:45:41Z

1

>>> l = ['', '', '', '']
>>> bool([_ for _ in l if _])
False
>>> l = ['', '', '', '', 1]
>>> bool([_ for _ in l if _])
True

answered Aug 30, 2012 at 15:45

Dr. Jan-Philip Gehrcke

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2 Comments

Steven Rumbalski Over a year ago

This is a bit awkward looking and it doesn't short circuit like not any(l).

Dr. Jan-Philip Gehrcke Over a year ago

I agree that this solution is far from optimal :)

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