Do not transform special characters in Python - python

I just want to print the original string.
[Case1] I know put "r" before the string can work
print r'123\r\n567"45'
>>`
123\r\n567"45
[Case2] But when it is a Variable
aaa = '123\r\n567"45'
print aaa
>>
123
567"45
Is there any function can print aaa with the same effect like Case1?

The obvious way to make Case 2 work like Case 1 is to use a raw string in your assignment statement:
aaa = r'123\r\n567"45'
Now when you print aaa, you'll get the actual backslashes and r and n characters, rather than a carriage return and a newline.
If you're actually loading aaa from some other source (rather than using a string literal), your task is a little bit more complicated. You'll actually need to transform the string in some way to get the output you want.
One simple way of doing something close to what you want is to use the repr function:
aaa = some_function() # returns '123\r\n567"45' and some_function can't be changed
print repr(aaa)
This will not quite do what you want though, since it will add quotation marks around the string's text. If you care about that, you could remove them with a slice:
print repr(aaa)[1:-1]
Another approach to take is to manually transform the characters you want escaped, e.g. with str.replace or str.translate. This is easy to do if you only care about escaping a few special characters and not others.
print aaa.replace('\r', r'\r').replace('\n', r'\n')
A final option is to use str.encode with the special character set called unicode-escape, which will escape all characters that are not printable ASCII:
print aaa.encode('unicode-escape')
This only works as intended in Python 2 however. In Python 3, str.encode always returns a bytes instance which you'd need to decode again to get a str (aaa.encode('unicode-escape').decode('ascii') would work, but it's really ugly).

You can do it using repr function in python:
If you are using python 2 then :
If you are using python 3 then :

If what you really want is just to print the original string, instead of prepending an r before the literal, you may want to use the python native function repr. E.g.
>>> aaa = '123\r\n567"45'
>>> print repr(aaa)
'123\r\n567"45'
which is equivalent in this (exact) case to
>>> print repr('123\r\n567"45')
'123\r\n567"45'

Related

Is it possible to use format() function with a string in format's place?

I'm using a format() in python and I want to use a variable pokablelio so that the person could choose how many numbers to output after the dot. When I try to put the variable alone after the comma it outputs: ValueError: Invalid format specifier. I tried replacing some characters or making the whole string in a parentheses but that didn't work.
Right now I'm wondering: Can I even use a variable as a string to put it in format's place?
(note: The machine should have a "'.10f'" string in the variable)
Error and the code
It is possible to use variables as part of the format specifier, just include them inside additional curly braces:
>>> n_places = 10
>>> f'{1.23:.{n_places}f}'
'1.2300000000'

How to convert a regular string to a raw string? [duplicate]

I have a string s, its contents are variable. How can I make it a raw string? I'm looking for something similar to the r'' method.
i believe what you're looking for is the str.encode("string-escape") function. For example, if you have a variable that you want to 'raw string':
a = '\x89'
a.encode('unicode_escape')
'\\x89'
Note: Use string-escape for python 2.x and older versions
I was searching for a similar solution and found the solution via:
casting raw strings python
Raw strings are not a different kind of string. They are a different way of describing a string in your source code. Once the string is created, it is what it is.
Since strings in Python are immutable, you cannot "make it" anything different. You can however, create a new raw string from s, like this:
raw_s = r'{}'.format(s)
As of Python 3.6, you can use the following (similar to #slashCoder):
def to_raw(string):
return fr"{string}"
my_dir ="C:\data\projects"
to_raw(my_dir)
yields 'C:\\data\\projects'. I'm using it on a Windows 10 machine to pass directories to functions.
raw strings apply only to string literals. they exist so that you can more conveniently express strings that would be modified by escape sequence processing. This is most especially useful when writing out regular expressions, or other forms of code in string literals. if you want a unicode string without escape processing, just prefix it with ur, like ur'somestring'.
For Python 3, the way to do this that doesn't add double backslashes and simply preserves \n, \t, etc. is:
a = 'hello\nbobby\nsally\n'
a.encode('unicode-escape').decode().replace('\\\\', '\\')
print(a)
Which gives a value that can be written as CSV:
hello\nbobby\nsally\n
There doesn't seem to be a solution for other special characters, however, that may get a single \ before them. It's a bummer. Solving that would be complex.
For example, to serialize a pandas.Series containing a list of strings with special characters in to a textfile in the format BERT expects with a CR between each sentence and a blank line between each document:
with open('sentences.csv', 'w') as f:
current_idx = 0
for idx, doc in sentences.items():
# Insert a newline to separate documents
if idx != current_idx:
f.write('\n')
# Write each sentence exactly as it appared to one line each
for sentence in doc:
f.write(sentence.encode('unicode-escape').decode().replace('\\\\', '\\') + '\n')
This outputs (for the Github CodeSearchNet docstrings for all languages tokenized into sentences):
Makes sure the fast-path emits in order.
#param value the value to emit or queue up\n#param delayError if true, errors are delayed until the source has terminated\n#param disposable the resource to dispose if the drain terminates
Mirrors the one ObservableSource in an Iterable of several ObservableSources that first either emits an item or sends\na termination notification.
Scheduler:\n{#code amb} does not operate by default on a particular {#link Scheduler}.
#param the common element type\n#param sources\nan Iterable of ObservableSource sources competing to react first.
A subscription to each source will\noccur in the same order as in the Iterable.
#return an Observable that emits the same sequence as whichever of the source ObservableSources first\nemitted an item or sent a termination notification\n#see ReactiveX operators documentation: Amb
...
Just format like that:
s = "your string"; raw_s = r'{0}'.format(s)
With a little bit correcting #Jolly1234's Answer:
here is the code:
raw_string=path.encode('unicode_escape').decode()
s = "hel\nlo"
raws = '%r'%s #coversion to raw string
#print(raws) will print 'hel\nlo' with single quotes.
print(raws[1:-1]) # will print hel\nlo without single quotes.
#raws[1:-1] string slicing is performed
The solution, which worked for me was:
fr"{orignal_string}"
Suggested in comments by #ChemEnger
I suppose repr function can help you:
s = 't\n'
repr(s)
"'t\\n'"
repr(s)[1:-1]
't\\n'
Just simply use the encode function.
my_var = 'hello'
my_var_bytes = my_var.encode()
print(my_var_bytes)
And then to convert it back to a regular string do this
my_var_bytes = 'hello'
my_var = my_var_bytes.decode()
print(my_var)
--EDIT--
The following does not make the string raw but instead encodes it to bytes and decodes it.

ZWNJ not shown properly in python 3.3

I am trying to replace the space between two tokens written in the Arabic alphabet with a ZWNJ but what the function returns is not decoded properly on the screen:
>>> nm.normalize("رشته ها")
'رشته\u200cها'
\u200 should be rendered as a half-space that would be placed between 'رشته' and 'ها' here, but it gets messed up like that. I am using Python 3.3.3
The function returned a string object with the \u200c character as part of it, but Python shows you the representation. The \uxxxx syntax is used to make the representation useful as a debugging value, you can now copy that representation and paste it back into Python and get the exact same value.
In other words, the function worked exactly as advertised; the space was indeed replaced by a U+200C ZERO WIDTH NON-JOINER codepoint.
If you wanted to write the string to your terminal or console, use print():
print(nm.normalize("رشته ها"))
Demo:
>>> result = 'رشته\u200cها'
>>> len(result)
7
>>> result[4]
'\u200c'
>>> print(result)
رشته‌ها
You can see that character 5 (index 4) is a single character here, not 6 separate characters.

ElementTree will not parse special characters with Python 2.7

I had to rewrite my python script from python 3 to python2 and after that I got problem parsing special characters with ElementTree.
This is a piece of my xml:
<account number="89890000" type="Kostnad" taxCode="597" vatCode="">Avsättning egenavgifter</account>
This is the ouput when I parse this row:
('account:', '89890000', 'AccountType:', 'Kostnad', 'Name:', 'Avs\xc3\xa4ttning egenavgifter')
So it seems to be a problem with the character "ä".
This is how i do it in the code:
sys.setdefaultencoding( "UTF-8" )
xmltree = ET()
xmltree.parse("xxxx.xml")
printAccountPlan(xmltree)
def printAccountPlan(xmltree):
print("account:",str(i.attrib['number']), "AccountType:",str(i.attrib['type']),"Name:",str(i.text))
Anyone have an ide to get the ElementTree parse the charracter "ä", so the result will be like this:
('account:', '89890000', 'AccountType:', 'Kostnad', 'Name:', 'Avsättning egenavgifter')
You're running into two separate differences between Python 2 and Python 3 at the same time, which is why you're getting unexpected results.
The first difference is one you're probably already aware of: Python's print statement in version 2 became a print function in version 3. That change is creating a special circumstance in your case, which I'll get to a little later. But briefly, this is the difference in how 'print' works:
In Python 3:
>>> # Two arguments 'Hi' and 'there' get passed to the function 'print'.
>>> # They are concatenated with a space separator and printed.
>>> print('Hi', 'there')
>>> Hi there
In Python 2:
>>> # 'print' is a statement which doesn't need parenthesis.
>>> # The parenthesis instead create a tuple containing two elements
>>> # 'Hi' and 'there'. This tuple is then printed.
>>> print('Hi', 'there')
>>> ('Hi', 'there')
The second problem in your case is that tuples print themselves by calling repr() on each of their elements. In Python 3, repr() displays unicode as you want. But in Python 2, repr() uses escape characters for any byte values which fall outside the printable ASCII range (e.g., larger than 127). This is why you're seeing them.
You may decide to resolve this issue, or not, depending on what you're goal is with your code. The representation of a tuple in Python 2 uses escape characters because it's not designed to be displayed to an end-user. It's more for your internal convenience as a developer, for troubleshooting and similar tasks. If you're simply printing it for yourself, then you may not need to change a thing because Python is showing you that the encoded bytes for that non-ASCII character are correctly there in your string. If you do want to display something to the end-user which has the format of how tuples look, then one way to do it (which retains correct printing of unicode) is to manually create the formatting, like this:
def printAccountPlan(xmltree):
data = (i.attrib['number'], i.attrib['type'], i.text)
print "('account:', '%s', 'AccountType:', '%s', 'Name:', '%s')" % data
# Produces this:
# ('account:', '89890000', 'AccountType:', 'Kostnad', 'Name:', 'Avsättning egenavgifter')

splitting unicode string into words

I am trying to split a Unicode string into words (simplistic), like this:
print re.findall(r'(?u)\w+', "раз два три")
What I expect to see is:
['раз','два','три']
But what I really get is:
['\xd1', '\xd0', '\xd0', '\xd0', '\xd0\xb2\xd0', '\xd1', '\xd1', '\xd0']
What am I doing wrong?
Edit:
If I use u in front of the string:
print re.findall(r'(?u)\w+', u"раз два три")
I get:
[u'\u0440\u0430\u0437', u'\u0434\u0432\u0430', u'\u0442\u0440\u0438']
Edit 2:
Aaaaand it seems like I should have read docs first:
print re.findall(r'(?u)\w+', u"раз два три")[0].encode('utf-8')
Will give me:
раз
Just to make sure though, does that sound like a proper way of approaching it?
You're actually getting the stuff you expect in the unicode case. You only think you are not because of the weird escaping due to the fact that you're looking at the reprs of the strings, not not printing their unescaped values. (This is just how lists are displayed.)
>>> words = [u'\u0440\u0430\u0437', u'\u0434\u0432\u0430', u'\u0442\u0440\u0438']
>>> for w in words:
... print w # This uses the terminal encoding -- _only_ utilize interactively
...
раз
два
три
>>> u'раз' == u'\u0440\u0430\u0437'
True
Don't miss my remark about printing these unicode strings. Normally if you were going to send them to screen, a file, over the wire, etc. you need to manually encode them into the correct encoding. When you use print, Python tries to leverage your terminal's encoding, but it can only do that if there is a terminal. Because you don't generally know if there is one, you should only rely on this in the interactive interpreter, and always encode to the right encoding explicitly otherwise.
In this simple splitting-on-whitespace approach, you might not want to use regex at all but simply to use the unicode.split method.
>>> u"раз два три".split()
[u'\u0440\u0430\u0437', u'\u0434\u0432\u0430', u'\u0442\u0440\u0438']
Your top (bytestring) example does not work because re basically assumes all bytestrings are ASCII for its semantics, but yours was not. Using unicode strings allows you to get the right semantics for your alphabet and locale. As much as possible, textual data should always be represented using unicode rather than str.

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