如何使用Python从字符串中删除字符

There is a string, for example. EXAMPLE.

How can I remove the middle character, i.e., M from it? I don’t need the code. I want to know:

• Do strings in Python end in any special character?
• Which is a better way – shifting everything right to left starting from the middle character OR creation of a new string and not copying the middle character?

In Python, strings are immutable, so you have to create a new string. You have a few options of how to create the new string. If you want to remove the ‘M’ wherever it appears:

newstr = oldstr.replace("M", "")

If you want to remove the central character:

midlen = len(oldstr)/2   # //2 in python 3
newstr = oldstr[:midlen] + oldstr[midlen+1:]

You asked if strings end with a special character. No, you are thinking like a C programmer. In Python, strings are stored with their length, so any byte value, including \0, can appear in a string.

This is probably the best way:

original = "EXAMPLE"
removed = original.replace("M", "")

Don’t worry about shifting characters and such. Most Python code takes place on a much higher level of abstraction.

To replace a specific position:

s = s[:pos] + s[(pos+1):]

To replace a specific character:

s = s.replace('M','')

Strings are immutable. But you can convert them to a list, which is mutable, and then convert the list back to a string after you’ve changed it.

s = "this is a string"

l = list(s)  # convert to list

l[1] = ""    # "delete" letter h (the item actually still exists but is empty)
l[1:2] = []  # really delete letter h (the item is actually removed from the list)
del(l[1])    # another way to delete it

p = l.index("a")  # find position of the letter "a"
del(l[p])         # delete it

s = "".join(l)  # convert back to string

You can also create a new string, as others have shown, by taking everything except the character you want from the existing string.

How can I remove the middle character, i.e., M from it?

You can’t, because strings in Python are immutable.

Do strings in Python end in any special character?

No. They are similar to lists of characters; the length of the list defines the length of the string, and no character acts as a terminator.

Which is a better way – shifting everything right to left starting from the middle character OR creation of a new string and not copying the middle character?

You cannot modify the existing string, so you must create a new one containing everything except the middle character.

Use the translate() method:

>>> s = 'EXAMPLE'
>>> s.translate(None, 'M')
'EXAPLE'

UserString.MutableString

Mutable way:

import UserString

s = UserString.MutableString("EXAMPLE")

>>> type(s)
<type 'str'>

# Delete 'M'
del s[3]

# Turn it for immutable:
s = str(s)

card = random.choice(cards)
cardsLeft = cards.replace(card, '', 1)

How to remove one character from a string: Here is an example where there is a stack of cards represented as characters in a string. One of them is drawn (import random module for the random.choice() function, that picks a random character in the string). A new string, cardsLeft, is created to hold the remaining cards given by the string function replace() where the last parameter indicates that only one “card” is to be replaced by the empty string…

def kill_char(string, n): # n = position of which character you want to remove
    begin = string[:n]    # from beginning to n (n not included)
    end = string[n+1:]    # n+1 through end of string
    return begin + end
print kill_char("EXAMPLE", 3)  # "M" removed

I have seen this somewhere here.

Here’s what I did to slice out the “M”:

s = 'EXAMPLE'
s1 = s[:s.index('M')] + s[s.index('M')+1:]

If you want to delete/ignore characters in a string, and, for instance, you have this string,

“[11:L:0]”

from a web API response or something like that, like a CSV file, let’s say you are using requests

import requests
udid = 123456
url = 'http://webservices.yourserver.com/action/id-' + udid
s = requests.Session()
s.verify = False
resp = s.get(url, stream=True)
content = resp.content

loop and get rid of unwanted chars:

for line in resp.iter_lines():
  line = line.replace("[", "")
  line = line.replace("]", "")
  line = line.replace('"', "")

Optional split, and you will be able to read values individually:

listofvalues = line.split(':')

Now accessing each value is easier:

print listofvalues[0]
print listofvalues[1]
print listofvalues[2]

This will print

11

L

0

To delete a char or a sub-string once (only the first occurrence):

main_string = main_string.replace(sub_str, replace_with, 1)

NOTE: Here 1 can be replaced with any int for the number of occurrence you want to replace.

You can simply use list comprehension.

Assume that you have the string: my name is and you want to remove character m. use the following code:

"".join([x for x in "my name is" if x is not 'm'])

from random import randint


def shuffle_word(word):
    newWord=""
    for i in range(0,len(word)):
        pos=randint(0,len(word)-1)
        newWord += word[pos]
        word = word[:pos]+word[pos+1:]
    return newWord

word = "Sarajevo"
print(shuffle_word(word))

Another way is with a function,

Below is a way to remove all vowels from a string, just by calling the function

def disemvowel(s):
    return s.translate(None, "aeiouAEIOU")

Strings are immutable in Python so both your options mean the same thing basically.