Removing a control character using Python - python

I have a script that processes the output of a command (the aws help cli command).
I step through the output line-by-line and don't start the actual real parsing until I encounter the text "AVAILABLE COMMANDS" at which point I set a flag to true and start further processing on each line.
I've had this working fine - BUT on Ubuntu we encounter a problem which is this :
The CLI highlights the text in a way I have not seen before:
The output is very long, so I've grep'd the particular line in question - see below:
># aws ec2 help | egrep '^A'
>AVAILABLE COMMANDS
># aws ec2 help | egrep '^A' | cat -vet
>A^HAV^HVA^HAI^HIL^HLA^HAB^HBL^HLE^HE C^HCO^HOM^HMM^HMA^HAN^HND^HDS^HS$
What I haven't seen before is that each letter that is highligted is in the format X^HX.
I'd like to apply a simple transformation of the type X^HX --> X (for all a-zA-Z).
What have I tried so far:
well my workaround is this - first I remove control characters like this:
String = re.sub(r'[\x00-\x1f\x7f-\x9f]','',String)
but I still have to search for 'AAVVAAIILLAABBLLEE' which is totally ugly. I considered using a further regex to turn doubles to singles but that will catch true doubles and get messy.
I started writing a function with an iteration across a constructed list of alpha characters to translate as described, and I used hexdump to try to figure out the exact \x code of the control characters in question but could not get it working - I could remove H but not the ^.
I really don't want to use any additional modules because I want to make this available to people without them having to install extras. In conclusion I have a workaround that is quite ugly, but I'm sure someone must know a quick an easy way to do this translation. It's odd that it only seems to show up on Ubuntu.

After looking at this a little further I was able to put in place a solution:
from string import ascii_lowercase
from string import ascii_uppercase
def RemoveUbuntuHighlighting(String):
for Char in ascii_uppercase + ascii_lowercase:
Match = Char + '\x08' + Char
String = re.sub(Match,Char,String)
return(String)
I'm still a little confounded to see characters highlighted in the format (X\x08X), the arrangement does seem to repeat the same information unnecessarily.
The other thing I would advise to anyone not familiar with reading hexcode is that each pair of hexes is swapped around with respect to the order of their appearance.

A much simpler and more reliable fix is to replace a backspace and duplicate of any character.
I have also augmented this to handle underscores using the same mechanism (character, backspace, underscore).
String = re.sub(r'(.)\x08(\1|_)', r'\1', String)
Demo: https://ideone.com/yzwd2V
This highlighting was standard back when output was to a line printer; backspacing and printing the same character again would add pigmentation to produce boldface. (Backspacing and printing an underscore would produce underlining.)
Probably the AWS CLI can be configured to disable this by setting the TERM variable to something like dumb. There is also a utility col which can remove this formatting (try col-b; maybe see also colcrt). Though perhaps really the best solution would be to import the AWS Python code and extract the help message natively.

Related

pywinauto escaping special characters

I am using type_keys() on a combobox to upload files via a file dialog. As mentioned in similar SO posts, this function omits certain special characters in the text that it actually types into the combobox. I'm resolving this by simply replacing every "specialchar" in that string with "{specialchar}". So far I've found the need to replace the following chars: + ^ % ( ).
I'm wondering where I can find the complete list of characters that require this treatment. I don't think it's this list because I'm not seeing, for example, the % symbol there. I also tried checking keyboard.py from the keyboard library but I don't know if it can be found there.
PS. I realize that instead of using type_keys(), for example, using send_keys() or set_edit_text(), the escaping of special characters might be done for me automatically. However, for various reasons, it looks like type_keys() works the best for my particular file dialog/situation.
Thanks
This is the full documentation: https://pywinauto.readthedocs.io/en/latest/code/pywinauto.keyboard.html All special characters can be wrapped by {}

wxPython/TextCtrl replacing a character within the first x lines of a string

I've scanned the questions here as well as the web and haven't found my answer, this is my first question and I'm a noobie to (wx)Python so go easy on me.
Using TextCtrl I'm trying to remove a single character within a string, this string will always start with the same set of characters but the rest of the string is freely editable by the user.
e.g
self.text=wx.TextCtrl(panel,-1"hello world,, today we're asking a question on stackoverflow, what would you ask?")
poor example but how would I find and remove the 11th(',') character so the sentence is more formatted without affecting the rest of the string?
I've tried standard python indexing but I get an error for that, I can successfully remove chunks of the string from the start outwards of the end inwards but I need only a single character removed.
Again, sorry for the poor terminology, as I said I'm fairly new to python so some of my terms may be a bit iffy.
self.text.SetValue(self.text.GetValue()[:10] + self.text.GetValue()[11:] )
maybe??
self.text.SetValue(self.text.GetValue().replace(",,",",")
maybe?
its not really clear what you are trying to accomplish here ...

[Python]How to deal with a string ending with one backslash?

I'm getting some content from Twitter API, and I have a little problem, indeed I sometimes get a tweet ending with only one backslash.
More precisely, I'm using simplejson to parse Twitter stream.
How can I escape this backslash ?
From what I have read, such raw string shouldn't exist ...
Even if I add one backslash (with two in fact) I still get an error as I suspected (since I have a odd number of backslashes)
Any idea ?
I can just forget about these tweets too, but I'm still curious about that.
Thanks : )
Prepending the string with r (stands for "raw") will escape all characters inside the string. For example:
print r'\b\n\\'
will output
\b\n\\
Have I understood the question correctly?
I guess you are looking a method similar to stripslashes in PHP. So, here you go:
Python version of PHP's stripslashes
You can try using raw strings by prepending an r (so nothing has to be escaped) to the string or re.escape().
I'm not really sure what you need considering I haven't seen the text of the response. If none of the methods you come up with on your own or get from here work, you may have to forget about those tweets.
Unless you update your question and come back with a real problem, I'm asserting that you don't have an issue except confusion.
You get the string from the Tweeter API, ergo the string does not show up in your code. “Raw strings” exist only in your code, and it is “raw strings” in code that can't end in a backslash.
Consider this:
def some_obscure_api():
"This exists in a library, so you don't know what it does"
return r"hello" + "\\" # addition just for fun
my_string = some_obscure_api()
print(my_string)
See? my_string happily ends in a backslash and your code couldn't care less.

using an alternative string quotation syntax in python

Just wondering...
I find using escape characters too distracting. I'd rather do something like this (console code):
>>> print ^'Let's begin and end with sets of unlikely 2 chars and bingo!'^
Let's begin and end with sets of unlikely 2 chars and bingo!
Note the ' inside the string, and how this syntax would have no issue with it, or whatever else inside for basically all cases. Too bad markdown can't properly colorize it (yet), so I decided to <pre> it.
Sure, the ^ could be any other char, I'm not sure what would look/work better. That sounds good enough to me, tho.
Probably some other language already have a similar solution. And, just maybe, Python already have such a feature and I overlooked it. I hope this is the case.
But if it isn't, would it be too hard to, somehow, change Python's interpreter and be able to select an arbitrary (or even standardized) syntax for notating the strings?
I realize there are many ways to change statements and the whole syntax in general by using pre-compilators, but this is far more specific. And going any of those routes is what I call "too hard". I'm not really needing to do this so, again, I'm just wondering.
Python has this use """ or ''' as the delimiters
print '''Let's begin and end with sets of unlikely 2 chars and bingo'''
How often do you have both of 3' and 3" in a string

Sensible python source line wrapping for printout

I am working on a latex document that will require typesetting significant amounts of python source code. I'm using pygments (the python module, not the online demo) to encapsulate this python in latex, which works well except in the case of long individual lines - which simply continue off the page. I could manually wrap these lines except that this just doesn't seem that elegant a solution to me, and I prefer spending time puzzling about crazy automated solutions than on repetitive tasks.
What I would like is some way of processing the python source code to wrap the lines to a certain maximum character length, while preserving functionality. I've had a play around with some python and the closest I've come is inserting \\\n in the last whitespace before the maximum line length - but of course, if this ends up in strings and comments, things go wrong. Quite frankly, I'm not sure how to approach this problem.
So, is anyone aware of a module or tool that can process source code so that no lines exceed a certain length - or at least a good way to start to go about coding something like that?
You might want to extend your current approach a bit, but using the tokenize module from the standard library to determine where to put your line breaks. That way you can see the actual tokens (COMMENT, STRING, etc.) of your source code rather than just the whitespace-separated words.
Here is a short example of what tokenize can do:
>>> from cStringIO import StringIO
>>> from tokenize import tokenize
>>>
>>> python_code = '''
... def foo(): # This is a comment
... print 'foo'
... '''
>>>
>>> fp = StringIO(python_code)
>>>
>>> tokenize(fp.readline)
1,0-1,1: NL '\n'
2,0-2,3: NAME 'def'
2,4-2,7: NAME 'foo'
2,7-2,8: OP '('
2,8-2,9: OP ')'
2,9-2,10: OP ':'
2,11-2,30: COMMENT '# This is a comment'
2,30-2,31: NEWLINE '\n'
3,0-3,4: INDENT ' '
3,4-3,9: NAME 'print'
3,10-3,15: STRING "'foo'"
3,15-3,16: NEWLINE '\n'
4,0-4,0: DEDENT ''
4,0-4,0: ENDMARKER ''
I use the listings package in LaTeX to insert source code; it does syntax highlight, linebreaks et al.
Put the following in your preamble:
\usepackage{listings}
%\lstloadlanguages{Python} # Load only these languages
\newcommand{\MyHookSign}{\hbox{\ensuremath\hookleftarrow}}
\lstset{
% Language
language=Python,
% Basic setup
%basicstyle=\footnotesize,
basicstyle=\scriptsize,
keywordstyle=\bfseries,
commentstyle=,
% Looks
frame=single,
% Linebreaks
breaklines,
prebreak={\space\MyHookSign},
% Line numbering
tabsize=4,
stepnumber=5,
numbers=left,
firstnumber=1,
%numberstyle=\scriptsize,
numberstyle=\tiny,
% Above and beyond ASCII!
extendedchars=true
}
The package has hook for inline code, including entire files, showing it as figures, ...
I'd check a reformat tool in an editor like NetBeans.
When you reformat java it properly fixes the lengths of lines both inside and outside of comments, if the same algorithm were applied to Python, it would work.
For Java it allows you to set any wrapping width and a bunch of other parameters. I'd be pretty surprised if that didn't exist either native or as a plugin.
Can't tell for sure just from the description, but it's worth a try:
http://www.netbeans.org/features/python/

Categories

Resources