Hướng dẫn before string in python

I'd like to remove all characters before a designated character or set of characters (for example):

Nội dung chính

• How do you remove part of a string before a certain character in Python?
• How do you remove part of a string after a specific character in Python?
• How do you trim a character in a string in Python?
• How do you delete something before a space in Python?

intro = "<>I'm Tom."

Now I'd like to remove the <> before I'm (or more specifically, I). Any suggestions?

asked Jun 19, 2015 at 19:20

SaroekinSaroekin

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4

Use re.sub. Just match all the chars upto I then replace the matched chars with I.

re.sub(r'^.*?I', 'I', stri)

answered Jun 19, 2015 at 19:22

Avinash RajAvinash Raj

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9

str.find could find character index of certain string's first appearance:

intro[intro.find('I'):]

answered Jun 7, 2018 at 12:56

duanduan

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2

Since index(char) gets you the first index of the character, you can simply do string[index(char):].

For example, in this case index("I") = 2, and intro[2:] = "I'm Tom."

answered Jun 19, 2015 at 19:22

AshkayAshkay

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3

If you know the character position of where to start deleting, you can use slice notation:

intro = intro[2:]

Instead of knowing where to start, if you know the characters to remove then you could use the lstrip() function:

intro = intro.lstrip("<>")

answered Jun 19, 2015 at 20:15

Brent WashburneBrent Washburne

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str = "<>I'm Tom."
temp = str.split("I",1)
temp[0]=temp[0].replace("<>","")
str = "I".join(temp)

answered Jun 19, 2015 at 19:26

3

I looped through the string and passed the index.

intro_list = []

intro = "<>I'm Tom."
for i in range(len(intro)):
    if intro[i] == '<' or intro[i] == '>':
        pass
    else:
        intro_list.append(intro[i])

intro = ''.join(intro_list)
print(intro)

answered Apr 28, 2020 at 7:22

>>> intro = "<>I'm Tom."
#Just split the string at the special symbol

>>> intro.split("<>")

Output = ['', "I'm Tom."]

>>> new = intro.split("<>")

>>> new[1]
"I'm Tom."

answered Feb 1, 2021 at 10:57

import re

date_div = "Blah blah\nblah, Updated: Aug. 23, 2012 Blah blah Updated: Feb. 13, 2019"

up_to_word = ":"
rx_to_first = r'^.*?{}'.format(re.escape(up_to_word))
rx_to_last = r'^.*{}'.format(re.escape(up_to_word))

# (Dot.) In the default mode, this matches any character except a newline. 
# If the DOTALL flag has been specified, this matches any character including a newline.

print("Remove all up to the first occurrence of the word including it:")
print(re.sub(rx_to_first, '', date_div, flags=re.DOTALL).strip())

print("Remove all up to the last occurrence of the word including it:")
print(re.sub(rx_to_last, '', date_div, flags=re.DOTALL).strip())

answered Aug 24, 2020 at 11:13

This solution works if the character is not in the string too, but uses if statements which can be slow.

if 'I' in intro:
  print('I' + intro.split('I')[1])
else:
  print(intro)

answered Jul 11, 2021 at 5:06

You can use itertools.dropwhile to all the characters before seeing a character to stop at. Then, you can use ''.join() to turn the resulting iterable back into a string:

from itertools import dropwhile
''.join(dropwhile(lambda x: x not in stop, intro))

This outputs:

I'm Tom.

answered Apr 10 at 23:26

BrokenBenchmarkBrokenBenchmark

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Based on the @AvinashRaj answer, you can use re.sub to substituate a substring by a string or a character thanks to regex:

missing import re

output_str = re.sub(r'^.*?I', 'I', input_str)

answered May 17 at 17:56

quentquent

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import re
intro = "<>I'm Tom."
re.sub(r'<>I', 'I', intro)

Tunaki

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answered Jun 5, 2016 at 5:58

1

How do you remove part of a string before a certain character in Python?

To remove everything before the first occurrence of the character '-' in a string, pass the character '-' as separator and 1 as the max split value. The split('-', 1) function will split the string into 2 parts, Part 1 should contain all characters before the first occurrence of character '-'.

How do you remove part of a string after a specific character in Python?

Use str..

a_string = "ab-cd".

split_string = a_string. split("-", 1) Split into "ab" and "cd".

substring = split_string[0].

print(substring).

How do you trim a character in a string in Python?

Use the . strip() method to remove whitespace and characters from the beginning and the end of a string. Use the . lstrip() method to remove whitespace and characters only from the beginning of a string.

How do you delete something before a space in Python?

strip() Python String strip() function will remove leading and trailing whitespaces. If you want to remove only leading or trailing spaces, use lstrip() or rstrip() function instead.