How do I trim whitespace from a string?

问题

How do I remove leading and trailing whitespace from a string in Python?

For example:

\" Hello \" --> \"Hello\"
\" Hello\"  --> \"Hello\"
\"Hello \"  --> \"Hello\"
\"Bob has a cat\" --> \"Bob has a cat\"

回答1:

Just one space, or all consecutive spaces? If the second, then strings already have a .strip() method:

>>> ' Hello '.strip()
'Hello'
>>> ' Hello'.strip()
'Hello'
>>> 'Bob has a cat'.strip()
'Bob has a cat'
>>> '   Hello   '.strip()  # ALL consecutive spaces at both ends removed
'Hello'

If you need only to remove one space however, you could do it with:

def strip_one_space(s):
    if s.endswith(" "): s = s[:-1]
    if s.startswith(" "): s = s[1:]
    return s

>>> strip_one_space("   Hello ")
'  Hello'

Also, note that str.strip() removes other whitespace characters as well (e.g. tabs and newlines). To remove only spaces, you can specify the character to remove as an argument to strip, i.e.:

>>> "  Hello\n".strip(" ")
'Hello\n'

回答2:

As pointed out in answers above

myString.strip()

will remove all the leading and trailing whitespace characters such as \n, \r, \t, \f, space.

For more flexibility use the following

Removes only leading whitespace chars: myString.lstrip()
Removes only trailing whitespace chars: myString.rstrip()
Removes specific whitespace chars: myString.strip('\n') or myString.lstrip('\n\r') or myString.rstrip('\n\t') and so on.

More details are available in the docs

回答3:

strip is not limited to whitespace characters either:

# remove all leading/trailing commas, periods and hyphens
title = title.strip(',.-')

回答4:

This will remove all leading and trailing whitespace in myString:

myString.strip()

回答5:

You want strip():

myphrases = [ " Hello ", " Hello", "Hello ", "Bob has a cat" ]

for phrase in myphrases:
    print phrase.strip()

回答6:

I wanted to remove the too-much spaces in a string (also in between the string, not only in the beginning or end). I made this, because I don't know how to do it otherwise:

string = "Name : David         Account: 1234             Another thing: something  " 

ready = False
while ready == False:
    pos = string.find("  ")
    if pos != -1:
       string = string.replace("  "," ")
    else:
       ready = True
print(string)

This replaces double spaces in one space until you have no double spaces any more

回答7:

I could not find a solution to what I was looking for so I created some custom functions. You can try them out.

def cleansed(s: str):
    """:param s: String to be cleansed"""
    assert s is not (None or "")
    # return trimmed(s.replace('"', '').replace("'", ""))
    return trimmed(s)


def trimmed(s: str):
    """:param s: String to be cleansed"""
    assert s is not (None or "")
    ss = trim_start_and_end(s).replace('  ', ' ')
    while '  ' in ss:
        ss = ss.replace('  ', ' ')
    return ss


def trim_start_and_end(s: str):
    """:param s: String to be cleansed"""
    assert s is not (None or "")
    return trim_start(trim_end(s))


def trim_start(s: str):
    """:param s: String to be cleansed"""
    assert s is not (None or "")
    chars = []
    for c in s:
        if c is not ' ' or len(chars) > 0:
            chars.append(c)
    return "".join(chars).lower()


def trim_end(s: str):
    """:param s: String to be cleansed"""
    assert s is not (None or "")
    chars = []
    for c in reversed(s):
        if c is not ' ' or len(chars) > 0:
            chars.append(c)
    return "".join(reversed(chars)).lower()


s1 = '  b Beer '
s2 = 'Beer  b    '
s3 = '      Beer  b    '
s4 = '  bread butter    Beer  b    '

cdd = trim_start(s1)
cddd = trim_end(s2)
clean1 = cleansed(s3)
clean2 = cleansed(s4)

print("\nStr: {0} Len: {1} Cleansed: {2} Len: {3}".format(s1, len(s1), cdd, len(cdd)))
print("\nStr: {0} Len: {1} Cleansed: {2} Len: {3}".format(s2, len(s2), cddd, len(cddd)))
print("\nStr: {0} Len: {1} Cleansed: {2} Len: {3}".format(s3, len(s3), clean1, len(clean1)))
print("\nStr: {0} Len: {1} Cleansed: {2} Len: {3}".format(s4, len(s4), clean2, len(clean2)))

回答8:

If you want to trim specified number of spaces from left and right, you could do this:

def remove_outer_spaces(text, num_of_leading, num_of_trailing):
    text = list(text)
    for i in range(num_of_leading):
        if text[i] == " ":
            text[i] = ""
        else:
            break

    for i in range(1, num_of_trailing+1):
        if text[-i] == " ":
            text[-i] = ""
        else:
            break
    return ''.join(text)

txt1 = "   MY name is     "
print(remove_outer_spaces(txt1, 1, 1))  # result is: "  MY name is    "
print(remove_outer_spaces(txt1, 2, 3))  # result is: " MY name is  "
print(remove_outer_spaces(txt1, 6, 8))  # result is: "MY name is"

来源：https://stackoverflow.com/questions/761804/how-do-i-trim-whitespace-from-a-string

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python

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