Python: How to Remove Empty Lists from a List

Python: How to remove empty lists from a list?

Try

list2 = [x for x in list1 if x != []]

If you want to get rid of everything that is "falsy", e.g. empty strings, empty tuples, zeros, you could also use

list2 = [x for x in list1 if x]

How to remove empty lists in python

Since empty lists evaluate to False with bool, you can use filter with None. Note L may be any iterable of lists, you need not begin with a list of lists.

L = [['JOB', 'APPLIED', 'FOR'], [], [], [], ['TEST'], ['SOMETHING ELSE']]

res = list(filter(None, L))

print(res)

[['JOB', 'APPLIED', 'FOR'], ['TEST'], ['SOMETHING ELSE']]

Remove empty strings from a list of strings

I would use filter:

str_list = filter(None, str_list)
str_list = filter(bool, str_list)
str_list = filter(len, str_list)
str_list = filter(lambda item: item, str_list)

Python 3 returns an iterator from filter, so should be wrapped in a call to list()

str_list = list(filter(None, str_list))

Remove empty nested lists - Python

I think what you want to do is

tscores = [x for x in tscores if x != []]

which make a list of only the none empty lists in tscores

How can I remove empty lists from within another list?

According to the docs for any(iterable):

Return True if any element of the iterable is true. If the iterable is empty, return False.

Hence when a list of Strings is passed to Any and if all of the elements in list are empty strings then it will return False as Empty String is equivalent to False.

So in your code replacing the second last line with:

fixed_paras = [x for x in paras if any(x)]

will eliminate the lists with empty strings too.

Note: This answer is based on juanpa.arrivillaga's comment

Removing empty sublists from a nested list

You have a mix of lists and strings, both of which are iterables. You need to explicitly test for lists here, and either recurse or use a stack:

def clean_nested(l):
    cleaned = []
    for v in l:
        if isinstance(v, list):
            v = clean_nested(v)
            if not v:
                continue
        cleaned.append(v)
    return cleaned

Demo:

>>> mynestedlist = [[[], [], [], ['Foo'], [], []], [[], ['Bar'], [], []], ['FOO'], 'BAR']
>>> clean_nested(mynestedlist)
[[['Foo']], [['Bar']], ['FOO'], 'BAR']

Note that this solution removes all but the outermost list if there are empty lists inside empty lists:

>>> nested_empty = [[[],[],[],[],[],[]],[[],['Bar'],[], []], ['FOO'], 'BAR']
>>> clean_nested(nested_empty)
[[['Bar']], ['FOO'], 'BAR']
>>> all_nested_empty = [[[],[],[],[],[],[]],[[],[],[], []], []]
>>> clean_nested(all_nested_empty)
[]

Python - delete empty lists from a list

You can use any(a_list), which is True if any element of a_list evaluates to True, as non-empty strings do.

data = [['#0721', '', '', '', ''], ['', '', '', '', ''], ['', '', '', '', ''], ['GBE COD', '746', '$2.00', '', '$1,492.00'], ['GBW COD', '13,894', '$0.50', '', '$6,947.00'], ['GOM COD', '60', '$2.00', '', '$120.00'], ['GB WINTER FLOUNDER', '94,158', '$0.25', '', '$23,539.50'], ['GOM WINTER FLOUNDER', '3,030', '$0.50', '', '$1,515.00'], ['GBE HADDOCK', '18,479', '$0.02', '', '$369.58'], ['GOM HADDOCK', '0', '$0.02', '', '$0.00'], ['GBW HADDOCK', '110,470', '$0.02', '', '$2,209.40'], ['HAKE', '259', '$1.30', '', '$336.70'], ['PLAICE', '3,738', '$0.40', '', '$1,495.20'], ['POLLOCK', '3,265', '$0.02', '', '$65.30'], ['WITCH FLOUNDER', '1,134', '$1.30', '', '$1,474.20'], ['SNE YT', '1,458', '$0.65', '', '$947.70'], ['GB YT', '4,499', '$0.70', '', '$3,149.30'], ['REDFISH', '841', '$0.02', '', '$16.82'], ['', '', '', '', ''], ['', '', '', '', ''], ['54 DAS @ $8.00/DAY = 432.00', '', ''], ['', '', '', '', '', '', '', '', ''], ['', '', '', '', '', '', '', '', '']]

non_empty = [sublist for sublist in data if any(sublist)]
print(non_empty)

[['#0721', '', '', '', ''],
 ['GBE COD', '746', '$2.00', '', '$1,492.00'],
 ['GBW COD', '13,894', '$0.50', '', '$6,947.00'],
 ['GOM COD', '60', '$2.00', '', '$120.00'],
 ['GB WINTER FLOUNDER', '94,158', '$0.25', '', '$23,539.50'],
 ['GOM WINTER FLOUNDER', '3,030', '$0.50', '', '$1,515.00'],
 ['GBE HADDOCK', '18,479', '$0.02', '', '$369.58'],
 ['GOM HADDOCK', '0', '$0.02', '', '$0.00'],
 ['GBW HADDOCK', '110,470', '$0.02', '', '$2,209.40'],
 ['HAKE', '259', '$1.30', '', '$336.70'],
 ['PLAICE', '3,738', '$0.40', '', '$1,495.20'],
 ['POLLOCK', '3,265', '$0.02', '', '$65.30'],
 ['WITCH FLOUNDER', '1,134', '$1.30', '', '$1,474.20'],
 ['SNE YT', '1,458', '$0.65', '', '$947.70'],
 ['GB YT', '4,499', '$0.70', '', '$3,149.30'],
 ['REDFISH', '841', '$0.02', '', '$16.82'],
 ['54 DAS @ $8.00/DAY = 432.00', '', '']]



Delete keys of a dictionary whose values are empty lists

What about:

new_d = dict((k,v) for k,v in d.items() if v)

And if you wish to overwrite d just change new_d to d.

There is some risk that might gives the wrong results:

if v when v = [] will evaluate to Falsly, same as 0 so it might remove wrong key. In my answer I didn't address that. One can refer to the following link to understand better: What is Truthy and Falsy? How is it different from True and False?

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