s='\'(-inf-24.5]\'' #this in not working
what should be put before \ to include it?
we have to assign s '\'(-inf-24.5]\''
the last two characters are two single quotes and not a single double quote.
the string should literally contain the given single backslashes as the string is to be inserted as it is in a column.
You can try this:
>>> s="\\'(-inf-24.5]\\'"
>>> print s
\'(-inf-24.5]\'
or
>>> s="'\\'(-inf-24.5]\\''"
>>> print s
'\'(-inf-24.5]\''
Basically, you will need to escape the backslash, when you write \' normally, python treats it as the ' being escaped. Also, python strings can be either "", or '', so you can mix them togather to get the desired result.
>>> s = r"'\'(-inf-24.5]\''"
>>> s
"'\\'(-inf-24.5]\\''"
>>> print(s)
'\'(-inf-24.5]\''
Prepending r before a string denotes a raw string, basically indicating to the interpreter that that string's characters should be taken literally. The only thing it can't do is end a string with a backslash (such a backslash would have to be concatenated from a separate string).
Related
For static strings, putting an r in front of the string would give the raw string (e.g. r'some \' string'). Since it is not possible to put r in front of a unicode string variable, what is the minimal approach to dynamically convert a string variable to its raw form? Should I manually substitute all backslashes with double backslashes?
str_var = u"some text with escapes e.g. \( \' \)"
raw_str_var = ???
If you really need to escape a string, let's say you want to print a newline as \n, you can use the encode method with the Python specific string_escape encoding:
>>> s = "hello\nworld"
>>> e = s.encode("string_escape")
>>> e
"hello\\nworld"
>>> print s
hello
world
>>> print e
hello\nworld
You didn't mention anything about unicode, or which Python version you are using, but if you are dealing with unicode strings you should use unicode_escape instead.
>>> u = u"föö\nbär"
>>> print u
föö
bär
>>> print u.encode('unicode_escape')
f\xf6\xf6\nb\xe4r
Your post originally had the regex tag, maybe re.escape is what you're actually looking for?
>>> re.escape(u"foo\nbar\'baz")
u"foo\\\nbar\\'baz"
Not the "double escapes", ie printing the above string yields:
foo\
bar\'baz
There is nothing to convert - the r prefix is only significant in source code notation, not for program logic.
As a rule, if you use a single backslash in a normal string, it will automatically be converted to a double backslash if it doesn't start a valid escape sequence:
>>> "\n \("
'\n \\('
Since it may be difficult to remember all the valid/invalid escape sequences, raw string notation was introduced. But there is no way and no need to convert a string after it has been defined.
In your case, the correct approach would be to use
str_var = ur"some text with escapes e.g. \( \' \)"
which happens to result in the same string here, but is more explicit.
I want to print the string. In my code i am not getting the right string.
line="\\python\001tag\file.txt"
str=re.search(r"\[(0-9)+]",line) (don't use raw_string here)
print str.group()
This gives nothing. I want to extract 001 from there.
Note: I don't want to use rawstring.because here user is getting the path from other resource. Is it possible to replace single slash by double slash to solve this problem
You need to use a raw-string so that escape sequences are not processed:
sat = r"\\Python\001tag\file.txt"
Demo:
>>> sat = r"\\Python\001tag\file.txt"
>>> sat
'\\\\Python\\001tag\\file.txt'
>>> print(sat)
\\Python\001tag\file.txt
>>>
Three errors: '\001' gives the codepoint in octal, actually the character at codepoint 1. Use double \\ or raw-strings.
Second: r'\[' escapes the '[', use double \\ instead: r'\\[+0-9()]' (I have rearranged the characters in the set, so that it doesn't look like a expression group.
Third: You want to look at str.group(0) to get the whole matched string.
In Python how would I write the string '"['BOS']"'.
I tried entering "\"['BOS']\"" but this gives the output '"[\'BOS\']"' with added backslashes in front of the '.
You can use triple quotes:
'''"['BOS']"'''
What you did ("\"['BOS']\"") is fine too. You get the backslashes on output, but they aren't part of the string:
>>> a = "\"['BOS']\""
>>> a
'"[\'BOS\']"' # this is the representation of the string
>>> print a
"['BOS']" # this is the actual content
When you type an expression such as a into the console, it's the same as writing print repr(a). repr(a) returns a string that can be used to reconstruct the original value, hence the quotes around the string and the backslashes.
You should use triple quotes so that you don't need to use backslashes.
'''"['BOS']"'''
The reason you got \s in your output is because the python console adds them:
>>> s = '''"['BOS']"'''
>>> s
'"[\'BOS\']"'
>>>
Enclose the entire string with """ or ''' (you would use ''' if the outermost quotation marks were ") in cases like these to make things simpler.
"""'"['BOS']"'"""
You can build it dynamically as well:
>>> print('"{}"'.format("'[BOS]'"))
"'[BOS]'"
>>> print('"'+"'[BOS]'"+'"')
"'[BOS]'"
This question already has answers here:
How can I put an actual backslash in a string literal (not use it for an escape sequence)?
(4 answers)
Closed 7 months ago.
In python, I am trying to replace a single backslash ("\") with a double backslash("\"). I have the following code:
directory = string.replace("C:\Users\Josh\Desktop\20130216", "\", "\\")
However, this gives an error message saying it doesn't like the double backslash. Can anyone help?
No need to use str.replace or string.replace here, just convert that string to a raw string:
>>> strs = r"C:\Users\Josh\Desktop\20130216"
^
|
notice the 'r'
Below is the repr version of the above string, that's why you're seeing \\ here.
But, in fact the actual string contains just '\' not \\.
>>> strs
'C:\\Users\\Josh\\Desktop\\20130216'
>>> s = r"f\o"
>>> s #repr representation
'f\\o'
>>> len(s) #length is 3, as there's only one `'\'`
3
But when you're going to print this string you'll not get '\\' in the output.
>>> print strs
C:\Users\Josh\Desktop\20130216
If you want the string to show '\\' during print then use str.replace:
>>> new_strs = strs.replace('\\','\\\\')
>>> print new_strs
C:\\Users\\Josh\\Desktop\\20130216
repr version will now show \\\\:
>>> new_strs
'C:\\\\Users\\\\Josh\\\\Desktop\\\\20130216'
Let me make it simple and clear. Lets use the re module in python to escape the special characters.
Python script :
import re
s = "C:\Users\Josh\Desktop"
print s
print re.escape(s)
Output :
C:\Users\Josh\Desktop
C:\\Users\\Josh\\Desktop
Explanation :
Now observe that re.escape function on escaping the special chars in the given string we able to add an other backslash before each backslash, and finally the output results in a double backslash, the desired output.
Hope this helps you.
Use escape characters: "full\\path\\here", "\\" and "\\\\"
In python \ (backslash) is used as an escape character. What this means that in places where you wish to insert a special character (such as newline), you would use the backslash and another character (\n for newline)
With your example string you would notice that when you put "C:\Users\Josh\Desktop\20130216" in the repl you will get "C:\\Users\\Josh\\Desktop\x8130216". This is because \2 has a special meaning in a python string. If you wish to specify \ then you need to put two \\ in your string.
"C:\\Users\\Josh\\Desktop\\28130216"
The other option is to notify python that your entire string must NOT use \ as an escape character by pre-pending the string with r
r"C:\Users\Josh\Desktop\20130216"
This is a "raw" string, and very useful in situations where you need to use lots of backslashes such as with regular expression strings.
In case you still wish to replace that single \ with \\ you would then use:
directory = string.replace(r"C:\Users\Josh\Desktop\20130216", "\\", "\\\\")
Notice that I am not using r' in the last two strings above. This is because, when you use the r' form of strings you cannot end that string with a single \
Why can't Python's raw string literals end with a single backslash?
https://pythonconquerstheuniverse.wordpress.com/2008/06/04/gotcha-%E2%80%94-backslashes-are-escape-characters/
Maybe a syntax error in your case,
you may change the line to:
directory = str(r"C:\Users\Josh\Desktop\20130216").replace('\\','\\\\')
which give you the right following output:
C:\\Users\\Josh\\Desktop\\20130216
The backslash indicates a special escape character. Therefore, directory = path_to_directory.replace("\", "\\") would cause Python to think that the first argument to replace didn't end until the starting quotation of the second argument since it understood the ending quotation as an escape character.
directory=path_to_directory.replace("\\","\\\\")
Given the source string, manipulation with os.path might make more sense, but here's a string solution;
>>> s=r"C:\Users\Josh\Desktop\\20130216"
>>> '\\\\'.join(filter(bool, s.split('\\')))
'C:\\\\Users\\\\Josh\\\\Desktop\\\\20130216'
Note that split treats the \\ in the source string as a delimited empty string. Using filter gets rid of those empty strings so join won't double the already doubled backslashes. Unfortunately, if you have 3 or more, they get reduced to doubled backslashes, but I don't think that hurts you in a windows path expression.
You could use
os.path.abspath(path_with_backlash)
it returns the path with \
Use:
string.replace(r"C:\Users\Josh\Desktop\20130216", "\\", "\\")
Escape the \ character.
I have
foo = '/DIR/abc'
and I want to convert it to
bar = '\\MYDIR\data\abc'
So, here's what I do in Python:
>>> foo = '/DIR/abc'
>>> bar = foo.replace(r'/DIR/',r'\\MYDIR\data\')
File "<stdin>", line 1
bar = foo.replace(r'/DIR/',r'\\MYDIR\data\')
^
SyntaxError: EOL while scanning string literal
If, however, I try to escape the last backslash by entering instead bar = foo.replace(r'/DIR/',r'\\MYDIR\data\\'), then I get this monstrosity:
>>> bar2
'\\\\MYDIR\\data\\\\abc'
Help! This is driving me insane.
The second argument should be a string, not a regex pattern:
foo.replace(r'/DIR/', '\\\\MYDIR\\data\\')
The reason you are encountering this is because of the behavior of the r"" syntax, Taking some explanation from the Python Documentation
r"\"" is a valid string literal consisting of two characters: a backslash and a double quote; r"\" is not a valid string literal (even a raw string cannot end in an odd number of backslashes). Specifically, a raw string cannot end in a single backslash (since the backslash would escape the following quote character).
So you will need to use a normal escaped string for the last argument.
>>> foo = "/DIR/abc"
>>> print foo.replace(r"/DIR/", "\\\\MYDIR\\data\\")
\\MYDIR\data\abc
I simply put a r in front of / to change the forward slash.
inv_num = line.replace(r'/', '-')
Two problems:
A raw literal simply cannot end with a single backslash because it is interpreted as escaping the quote character. Therefore, use a regular (non-raw) literal with escapes: '\\\\MYDIR\\data\\'.
When displayed (using the repr style), strings will appear with escapes. Therefore, '\\\\' only has two actual backslashes. So, '\\\\MYDIR\\data\\\\abc' is really \\MYDIR\data\\abc.
path=path.replace(r"/","\") will replace path=C:/folder with path=C:\folder