Add 'r' prefix to a python variable

Question

I have string variable which is

temp = '1\2\3\4'

I would like to add a prefix 'r' to the string variable and get

r'1\2\3\4'

so that I can split the string based on '\'. I tried the following:

r'temp'
'r' + temp
r + temp

But none of the above works. Is there a simple to do it? I'm using python 3. I also tried to encode the string, using

temp.encode('string-escape')

But it returns the following error

LookupError: unknown encoding: string-escape

How are the strings being created in the first place? If you are doing it in your code, just add the r yourself in the code? If you are getting the input from the user, then the user needs to input the correct string in the first place. — SethMMorton
– SethMMorton, Commented Dec 15, 2016 at 3:00
The string is actually a file location that is generated using glob.iglob () function. I would like to get all the txt file in a certain file, and I would like to extract the name of those files by splitting '\'. — ycenycute
– ycenycute, Commented Dec 15, 2016 at 3:18
The results of glob.iglob() should not suffer any escaping problem trying to do this post-escape isn't necessary. — SethMMorton
– SethMMorton, Commented Dec 15, 2016 at 3:20

Amadan · Accepted Answer · 2016-12-15 04:20:47Z

9

r is a prefix for string literals. This means, r"1\2\3\4" will not interpret \ as an escape when creating the string value, but keep \ as an actual character in the string. Thus, r"1\2\3\4" will have seven characters.

You already have the string value: there is nothing to interpret. You cannot have the r prefix affect a variable, only a literal.

Your temp = "1\2\3\4" will interpret backslashes as escapes, create the string '1\x02\x03\x04' (a four-character string), then assign this string to the variable temp. There is no way to retroactively reinterpret the original literal.

EDIT: In view of the more recent comments, you do not seem to, in fact, have a string "1\2\3\4". If you have a valid path, you can split it using

path.split(r'\')

or

path.split('\\')

but you probably also don't need that; rather, you may want to split a path into directory and file name, which is best done by os.path functions.

edited Dec 15, 2016 at 4:20

answered Dec 15, 2016 at 2:24

Amadan

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2 Comments

ycenycute Over a year ago

Then how can I split the string variable? I would like to have results like ['1', '2', '3', '4']. I know I can do with r'1\2\3\4', but not '1\2\3\4'

Amadan Over a year ago

There is nothing to split. "1\2\3\4" does not contain the characters 2, 3 or 4.

demongolem · Accepted Answer · 2020-06-09 16:51:21Z

4

Wouldn't it just be re.escape(temp)?

Take for example the use case of trying to generate a pattern on the fly involving word boundaries. Then you can do this

r'\b' + re.escape(temp) + r'\b'

answered Jun 9, 2020 at 16:51

demongolem

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Comments

Uday Singh · Accepted Answer · 2018-05-28 11:22:54Z

-4

just to prefix r in variable in search, Please do this r+""+temp. e.g.-

import re
email_address = 'Please contact us at: [email protected]'
searchString = "([\w\.-]+)@([\w\.-]+)"
re.serach(r""+searchString, email_address)

answered May 28, 2018 at 11:22

Uday Singh

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