Help with quote marks in regular expressions

CalibUser · 07-20-2015, 09:17 AM

Hi,

I am writing a plugin that needs to remove a space following the quote mark in the expression:

'

I have looked on the web for solutions. One solution was to use triple quote marks so I tried:

html = re.sub(r'''' ''', r''''''', html)

but this produced the error: EOL while scanning string literal.

I tried escaping the single quote mark in the replacement expression but that also produced an error.

Another web solution suggested placing the regular expressions in double quotes, so I tried the following and it worked:

html = re.sub(r"' ", r"'", html)

My question is: Suppose I have a replacement expression that contains both single and double quote marks. How could I write a replacement expression that includes a mixture of both?

theducks · 07-20-2015, 10:39 AM

This is the Sigil forum,
I am not sure Calibre query syntax works here in all cases.

BTW If you are working on a Sigil PI, I can move this thread. Just ask.

eschwartz · 07-20-2015, 01:35 PM

Code:

r'''<p>''''

Four single-quotes in a row -- the first three terminated the string literal, the last one began a new string literal.
You would need to escape it, but as you may have noticed, the backslash stays in the string. This only happens because you are using a raw string literal -- using

Code:

html = re.sub('''<p>' ''', '''<p>\'''', html)

works as expected.
Raw string literals are useful for strings in which you expect to have literal backslashes. That does not apply here.

Double-quotes work too, of course.

If you need to use both single- and double-quotes, make sure to escape whatever your delimiter is.

CalibUser · 07-20-2015, 02:14 PM

theducks - thanks for your response. The code that I put in my last post was not developed from Calibre (as my user name may suggest - I am going returning to Sigil for editing ePub books since the Sigil is continuing to be developed); I am learning Python for making Sigil plugins and could not find a way to put single and double quotes into the replacement expression and I wondered how this can be achieved.

eschwartz - thanks for providing a solution. I am new to Python so I am trying to learn how to use it. I will try your solution later.

07-20-2015, 09:17 AM	#1
CalibUser Addict Posts: 201 Karma: 62362 Join Date: Jul 2015 Device: Sony	Help with quote marks in regular expressions Hi, I am writing a plugin that needs to remove a space following the quote mark in the expression: <p>' I have looked on the web for solutions. One solution was to use triple quote marks so I tried: html = re.sub(r'''<p>' ''', r'''<p>'''', html) but this produced the error: EOL while scanning string literal. I tried escaping the single quote mark in the replacement expression but that also produced an error. Another web solution suggested placing the regular expressions in double quotes, so I tried the following and it worked: html = re.sub(r"<p>' ", r"<p>'", html) My question is: Suppose I have a replacement expression that contains both single and double quote marks. How could I write a replacement expression that includes a mixture of both?

07-20-2015, 01:35 PM	#3
eschwartz Ex-Helpdesk Junkie Posts: 19,422 Karma: 85397180 Join Date: Nov 2012 Location: The Beaten Path, USA, Roundworld, This Side of Infinity Device: Kindle Touch fw5.3.7 (Wifi only)	Code: r'''<p>'''' Four single-quotes in a row -- the first three terminated the string literal, the last one began a new string literal. You would need to escape it, but as you may have noticed, the backslash stays in the string. This only happens because you are using a raw string literal -- using Code: html = re.sub('''<p>' ''', '''<p>\'''', html) works as expected. Raw string literals are useful for strings in which you expect to have literal backslashes. That does not apply here. Double-quotes work too, of course. If you need to use both single- and double-quotes, make sure to escape whatever your delimiter is. Last edited by eschwartz; 07-20-2015 at 01:46 PM.

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07-20-2015, 10:39 AM	#2
theducks Well trained by Cats Posts: 29,818 Karma: 54830978 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	This is the Sigil forum, I am not sure Calibre query syntax works here in all cases. BTW If you are working on a Sigil PI, I can move this thread. Just ask.

07-20-2015, 02:14 PM	#4
CalibUser Addict Posts: 201 Karma: 62362 Join Date: Jul 2015 Device: Sony	theducks - thanks for your response. The code that I put in my last post was not developed from Calibre (as my user name may suggest - I am going returning to Sigil for editing ePub books since the Sigil is continuing to be developed); I am learning Python for making Sigil plugins and could not find a way to put single and double quotes into the replacement expression and I wondered how this can be achieved. eschwartz - thanks for providing a solution. I am new to Python so I am trying to learn how to use it. I will try your solution later.