Python Regex String Extraction

Question

I'm trying to extract two strings from this string using Regular Expressions -

'<img src="http://images.efollett.com/books/978/047/012/9780470129296.gif" width="80" height="100" alt="Organic Chemistry I (as Second Language)" />'

I want the URL after src and the text after alt (so Organic Chemistry I (as Second Language)) and the url)

I've tried ('<img src=(\w+)" width'), ('<img src="(\w+)"') and ('src="(\w+)"\swidth'), for the url and all return empty.

I've also tried ('alt="(\w+)"') for the name and again, no luck.

Can anyone help?

Acorn · Accepted Answer · 2011-09-12 10:14:16Z

3

Use lxml.

import lxml.html

html_string = '<img src="http://images.efollett.com/books/978/047/012/9780470129296.gif" width="80" height="100" alt="Organic Chemistry I (as Second Language)" />'

img = lxml.html.fromstring(html_string)

print "src:", img.get("src")
print "alt:", img.get("alt")

Gives:

src: http://images.efollett.com/books/978/047/012/9780470129296.gif
alt: Organic Chemistry I (as Second Language)

answered Sep 12, 2011 at 10:14

Acorn

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Comments

Community · Accepted Answer · 2017-05-23 12:31:52Z

2

Although you should not be parsing HTML with regexes, I can point out a common error here with regexes, which is your use of \w. That only matches A-Z, a-z, 0-9, and underscores. Not slashes, not parentheses. If you are trying to pull data out of attributes, use "([^"]*)" or "(.*?)"

edited May 23, 2017 at 12:31

CommunityBot

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answered Sep 12, 2011 at 6:58

Ray Toal

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2 Comments

praks5432 Over a year ago

two questions- first how else would I extract the information that I want (I'm using Beautiful Soup and the other form of the above is as a BeautifulSoup tag)? Second, what regex can I use to get what I want?

Ray Toal Over a year ago

Oh apologies then, I did not know you were using Beautiful Soup, which is an HTML parser! There are hints in this SO question.

eph · Accepted Answer · 2011-09-12 07:10:04Z

1

You can try r'<img[^>]*\ssrc="(.*?)"' and r'<img[^>]*\salt="(.*?)"'.

I don't know if you are dealing with HTML. [^>]* is to ensure inside brackets. \s is used to avoid some tags like "xxxsrc", and take care of newlines.

edited Sep 12, 2011 at 7:10

answered Sep 12, 2011 at 7:03

eph

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1 Comment

Ray Toal Over a year ago

This works but backtracks. Probably okay for small img tags. +1 for correctness.

scessor · Accepted Answer · 2011-09-12 07:26:55Z

0

I don't know python, but may this regular expression helps?

<img.*?src="([^"]*)".*?alt="([^"]*)".*?>

edited Sep 12, 2011 at 7:26

answered Sep 12, 2011 at 7:02

scessor

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2 Comments

Ray Toal Over a year ago

This works provided the src comes before the alt. Also a tip for efficiency: don't use .* in the middle of a regex. .*? is more appropriate in this case.

scessor Over a year ago

Thanks, updated. You're right, only if the string is given as described in the question (alt after src attribute) this regex makes sense.

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