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
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.
To replace a specific position:
s = s[:pos] + s[(pos+1):]
To replace a specific character:
s = s.replace('M','')
l
. Then for the first part, the constraint for pos should be l-1 > pos >= 0
.
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.
M
might not be unique. In that case, this will replace all the M
s, right?
n
occurrences, use original.replace("M", "", n)
.
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.
str.replace
method?
t use
str.replace()` to surgically replace a specific character (e.g. "character at index 10")
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'
None
to remove seems not to work): translate( str.maketrans("<>", " ") )
str.maketrans( "", "", "<>")
and str.maketrans( {"<":None,">":None })
'EXAMPLE'.translate({ord("M"): None})
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.
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...
On Python 2, you can use UserString.MutableString to do it in a mutable way:
>>> import UserString
>>> s = UserString.MutableString("EXAMPLE")
>>> type(s)
<class 'UserString.MutableString'>
>>> del s[3] # Delete 'M'
>>> s = str(s) # Turn it into an immutable value
>>> s
'EXAPLE'
MutableString
was removed in Python 3.
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")
s.translate(str.maketrans("", "", "aeiouAEIOU"))
?
Here's what I did to slice out the "M":
s = 'EXAMPLE'
s1 = s[:s.index('M')] + s[s.index('M')+1:]
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'])
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
Two new string removal methods are introduced in Python 3.9+
#str.removeprefix("prefix_to_be_removed")
#str.removesuffix("suffix_to_be_removed")
s='EXAMPLE'
In this case position of 'M' is 3
s = s[:3] + s[3:].removeprefix('M')
OR
s = s[:4].removesuffix('M') + s[4:]
#output'EXAPLE'
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))
Strings are immutable in Python so both your options mean the same thing basically.
Success story sharing
from __future__ import division
at the beginning of your script will make version 2.X python act like version 3.X""
doesn't imply an empty line. If you put it in a list, and join it with newlines, then it will make an empty line, but there are lots of other places you might use an empty string that won't do that.