Deleting specific control characters(\n \r \t) from a string

Question

I have quite large amount of text which include control charachters like \\n \\t and \\r. I need to replace them with a simple space--> \" \". What is the fastest way to do this

Answer 1

using regex

re.sub(r'\s+', ' ', '1\n2\r3\t4')

without regex

>>> ' '.join('1\n\n2\r3\t4'.split())
'1 2 3 4'
>>>

Answer 2

You may also try regular expressions:

import re
regex = re.compile(r'[\n\r\t]')
regex.sub(' ', my_str)

Answer 3

>>> re.sub(r'[\t\n\r]', ' ', '1\n2\r3\t4')
'1 2 3 4'

Answer 4

my_string is the string where you want to delete specific control characters. As strings are immutable in python, after substitute operation you need to assign it to another string or reassign it:

my_string = re.sub(r'[\n\r\t]*', '', my_string)

Answer 5

If you want to normalise whitespace (replace runs of one or more whitespace characters by a single space, and strip leading and trailing whitespace) this can be accomplished by using string methods:

>>> text = '   foo\tbar\r\nFred  Nurke\t Joe Smith\n\n'
>>> ' '.join(text.split())
'foo bar Fred Nurke Joe Smith'

Answer 6

I think the fastest way is to use str.translate():

import string
s = "a\nb\rc\td"
print s.translate(string.maketrans("\n\t\r", "   "))

prints

a b c d

EDIT: As this once again turned into a discussion about performance, here some numbers. For long strings, translate() is way faster than using regular expressions:

s = "a\nb\rc\td " * 1250000

regex = re.compile(r'[\n\r\t]')
%timeit t = regex.sub(" ", s)
# 1 loops, best of 3: 1.19 s per loop

table = string.maketrans("\n\t\r", "   ")
%timeit s.translate(table)
# 10 loops, best of 3: 29.3 ms per loop

That's about a factor 40.