Search strings with python

Question

I would like to know how can I search specific strings with python. Actually I opened a markdown file which contain a sheet like below:

| --------- | -------- | --------- |
|**propped**| - | -a flashlight in one hand and a large leather-bound book (A History of Magic by Bathilda Bagshot) propped open against the pillow. |
|**Pointless**| - | -“Witch Burning in the Fourteenth Century Was Completely Pointless — discuss.”|
|**unscrewed**| - | -Slowly and very carefully he unscrewed the ink bottle, dipped his quill into it, and began to write,|
|**downtrodden**| - | -For years, Aunt Petunia and Uncle Vernon had hoped that if they kept Harry as downtrodden as possible, they would be able to squash the magic out of him.|
|**sheets,**| - | -As long as he didn’t leave spots of ink on the sheets, the Dursleys need never know that he was studying magic by night.|
|**flinch**| - | -But he hoped she’d be back soon — she was the only living creature in this house who didn’t flinch at the sight of him.|

And I have to get the strings from each lines which decorates with |** **|, like:

propped
Pointless
unscrewed
downtrodden
sheets
flinch

I tried to use the regular expression but failed to extract it.

original markdown file content is like: | --------- | -------- | --------- | |**propped**| - | -a flashlight in one hand and a large leather-bound book (A History of Magic by Bathilda Bagshot) propped open against the pillow. | |**Pointless**| - | -“Witch Burning in the Fourteenth Century Was Completely Pointless — discuss.”| — Marco Mei
– Marco Mei, Commented Feb 26, 2017 at 16:46
There are online regex testers that use Python flavored regular expressions - they are very useful for fine tuning a pattern. — wwii
– wwii, Commented Feb 26, 2017 at 17:25

Dhruv Baveja · Accepted Answer · 2017-02-26 17:59:44Z

2

import re

y = '(?<=\|\*{2}).+?(?=,{0,1}\*{2}\|)'
reg = re.compile(y)
a = '| --------- | -------- | --------- | |**propped**| - | -a flashlight in one hand and a large leather-bound book (A History of Magic by Bathilda Bagshot) propped open against the pillow. | |**Pointless**| - | -“Witch Burning in the Fourteenth Century Was Completely Pointless — discuss.”|'
reg.findall(a)

Regex(y) above explained:

(?<=\|\*{2}) - Matches if the current position in the string is preceded by a match for \|\*{2} i.e. |**

.+? - Will try to find anything(except for new line) repeated 1 or more times. Adding ? after the qualifier makes it perform the match in non-greedy or minimal fashion; as few characters as possible will be matched.

(?=,{0,1}\*{2}\|) - ?= matches any string preceding the regex mentioned. In this case I have mentioned ,{0,1}\*{2}\|, which means zero or one , and 2 * and ending |.

edited Feb 26, 2017 at 17:59

answered Feb 26, 2017 at 17:52

Dhruv Baveja

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3 Comments

Dhruv Baveja Over a year ago

@MarcoMei if the solution works for you, can you please upvote it. Thanks

Marco Mei Over a year ago

Hi, Dhruv Baveja. Thanks for your kindness and useful help, it works completely well and for sure I'd like to upvote it but when I tried to do that it prompted "Thanks for your feedback,votes cast by those with less than 15 reputation are recorded, but do not change the publicly displayed post score." Any other thing i can do?

Dhruv Baveja Over a year ago

@MarcoMei Oh ok. Not an issue but good to hear that the solution worked for you. Thanks a lot for trying.

m87 · Accepted Answer · 2017-02-26 16:54:36Z

1

Try using the following regex :

(?<=\|)(?!\s).*?(?!\s)(?=\|)

see demo / explanation

answered Feb 26, 2017 at 16:54

m87

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2 Comments

Marco Mei Over a year ago

Thanks so much. and the web site you shared is very useful.

m87 Over a year ago

@MarcoMei its ok. have a nice day. :)

wwii · Accepted Answer · 2017-02-26 17:42:32Z

0

If the asterisks are in the text you are searching and you do not want the comma after sheets. The pattern would be a pipe followed by two asterisks then anything that follows that is not an asterisk or a comma.

\|\*{2}([^*,]+)

If you can live with the comma or if there might be commas you want to catch

\|\*{2}([^*]+)

Use either pattern with re.findall or re.finditer to capture the text you want.

If using the second pattern, you would need to run through the groups and strip any unwanted commas.

answered Feb 26, 2017 at 17:42

wwii

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1 Comment

Marco Mei Over a year ago

yes, sure, glad to do that but I have no idea how to accept it since it's my first time to post question here, would you mind to tell me how to do it?

Aashutosh jha · Accepted Answer · 2017-02-27 09:10:13Z

0

I have wrote below program to achieve the required output. I created a file string_test where all raw strings I copied:

a=re.compile("^\|\*\*([^*,]+)")
with open("string_test","r") as file1:
for i in file1.readlines():
    match=a.search(i)
    if match:
         print match.group(1)

answered Feb 27, 2017 at 9:10

Aashutosh jha

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