CODEWITHSUNDEEP
pythonlist
Alexa Elis
Alexa Elis

Reputation: 7709

How to remove empty string in a list?

For example I have a sentence 

"He is so .... cool!"

Then I remove all the punctuation and make it in a list.

["He", "is", "so", "", "cool"]

How do I remove or ignore the empty string?

Upvotes: 24

Views: 95024

Answers (9)

Usman Gani
Usman Gani

Reputation: 377

lst = ["He", "is", "so", "", "cool"]
lst = list(filter(str.strip, lst))

Upvotes: 0

Areza
Areza

Reputation: 6080

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

str_list = list(filter(None, str_list)) # fastest

Upvotes: 1

Lauritz V. Thaulow
Lauritz V. Thaulow

Reputation: 50975

I'll give you the answer to the question you should have asked -- how to avoid the empty string altogether. I assume you do something like this to get your list:

>>> "He is so .... cool!".replace(".", "").split(" ")
['He', 'is', 'so', '', 'cool!']

The point is that you use .split(" ") to split on space characters. However, if you leave out the argument to split, this happens:

>>> "He is so .... cool!".replace(".", "").split()
['He', 'is', 'so', 'cool!']

Quoth the docs:

If sep is not specified or is None, a different splitting algorithm is applied: runs of consecutive whitespace are regarded as a single separator, and the result will contain no empty strings at the start or end if the string has leading or trailing whitespace.

So you really don't need to bother with the other answers (except Blender's, which is a totally different approach), because split can do the job for you!

Upvotes: 5

Volatility
Volatility

Reputation: 32300

You can use filter, with None as the key function, which filters out all elements which are Falseish (including empty strings)

>>> lst = ["He", "is", "so", "", "cool"]
>>> filter(None, lst)
['He', 'is', 'so', 'cool']

Note however, that filter returns a list in Python 2, but a generator in Python 3. You will need to convert it into a list in Python 3, or use the list comprehension solution.

Falseish values include:

False
None
0
''
[]
()
# and all other empty containers

Upvotes: 52

msvalkon
msvalkon

Reputation: 12077

You can filter it like this

orig = ["He", "is", "so", "", "cool"]
result = [x for x in orig if x]

Or you can use filter. In python 3 filter returns a generator, thus list() turns it into a list. This works also in python 2.7

result = list(filter(None, orig))

Upvotes: 25

mchail
mchail

Reputation: 831

You can do this with a filter.

a = ["He", "is", "so", "", "cool"]
filter(lambda s: len(s) > 0, a)

Upvotes: -1

Blender
Blender

Reputation: 298048

You can use a list comprehension:

cleaned = [x for x in your_list if x]

Although I would use regex to extract the words:

>>> import re
>>> sentence = 'This is some cool sentence with,    spaces'
>>> re.findall(r'(\w+)', sentence)
['This', 'is', 'some', 'cool', 'sentence', 'with', 'spaces']

Upvotes: 7

Yuushi
Yuushi

Reputation: 26040

You can filter out empty strings very easily using a list comprehension:

x = ["He", "is", "so", "", "cool"]
x = [str for str in x if str]
>>> ['He', 'is', 'so', 'cool']

Upvotes: 1

jamylak
jamylak

Reputation: 133494

>>> from string import punctuation
>>> text = "He is so .... cool!"
>>> [w.strip(punctuation) for w in text.split() if w.strip(punctuation)]
['He', 'is', 'so', 'cool']

Upvotes: 2

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