Python: Removing spaces from list objects

I have a list of objects appended from a mysql database and contain spaces. I wish to remove the spaces such as below, but the code im using doesnt work?

hello = ['999 ',' 666 ']

k = []

for i in hello:
    str(i).replace(' ','')

print k

Here is Solutions:

We have many solutions to this problem, But we recommend you to use the first solution because it is tested & true solution that will 100% work for you.

Solution 1

Strings in Python are immutable (meaning that their data cannot be modified) so the replace method doesn’t modify the string – it returns a new string. You could fix your code as follows:

for i in hello:
    j = i.replace(' ','')

However a better way to achieve your aim is to use a list comprehension. For example the following code removes leading and trailing spaces from every string in the list using strip:

hello = [x.strip(' ') for x in hello]

Solution 2

List comprehension [num.strip() for num in hello] is the fastest.

>>> import timeit
>>> hello = ['999 ',' 666 ']

>>> t1 = lambda: map(str.strip, hello)
>>> timeit.timeit(t1)

>>> t2 = lambda: list(map(str.strip, hello))
>>> timeit.timeit(t2)

>>> t3 = lambda: [num.strip() for num in hello]
>>> timeit.timeit(t3)

>>> t4 = lambda: [num.replace(' ', '') for num in hello]
>>> timeit.timeit(t4)

Solution 3

result = map(str.strip, hello)

Solution 4

String methods return the modified string.

k = [x.replace(' ', '') for x in hello]

Solution 5

Presuming that you don’t want to remove internal spaces:

def normalize_space(s):
    """Return s stripped of leading/trailing whitespace
    and with internal runs of whitespace replaced by a single SPACE"""
    # This should be a str method :-(
    return ' '.join(s.split())

replacement = [normalize_space(i) for i in hello]

Solution 6

for element in range(0,len(hello)):
      d[element] = hello[element].strip()

Solution 7

replace() does not operate in-place, you need to assign its result to something. Also, for a more concise syntax, you could supplant your for loop with a one-liner: hello_no_spaces = map(lambda x: x.replace(' ', ''), hello)

Note: Use and implement solution 1 because this method fully tested our system.
Thank you 🙂

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