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I have a string and this string could contain some occurrences like:

http://site/image.jpg

What is the right way to replace, when it's present, this kind of occurrence by

<img src="http://site/image.jpg">

What is really important, is to replace only occurrences beginning by http and which ending by .jpg, .png and gif by the <img> HTML tag.

So if among all the text there is a URL link of any images, it's formatted by a HTML tag to display the image.

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  • You should look into regular expressions which can be used to work with strings Commented Aug 9, 2017 at 12:44

2 Answers 2

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Pretty straightforward with regex:

import re

string = 'some other text, a URL http://site/image.jpg and other text'

print(re.sub(r'(https?.+?(?:jpg|png|gif))', r'<img src="\1">', string))

# some other text, a URL <img src="http://site/image.jpg"> and other text

(https?.+(?:jpg|png|gif)) matches everything that starts with http or https and ending with jpg, png or gif.

'<img src="\1">' here the \1 refers to the first (and only) capture group in the previous regex (which contains the image url).

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5 Comments

Unfortunately your regexp matches literally everything that starts with http and ending with .jpg/png/gif, so if there is more than one link separated by some text - this text also will be captured. Please check example: regex101.com/r/eYVuXF/1
@erhesto Ok, fixed. Was only a matter of changing .+ to the lazy .+? regex101.com/r/eYVuXF/2
Still not totally comfortable situation, as things like in example: regex101.com/r/eYVuXF/3 are captured, but maybe it will be enough for OP, so I'm removing downvote.
@erhesto Well, OP did not ask for a url verifier.
Thanks everyone for your help, I think to get a solution by AJAX/JQUERY
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This is a simple answer to your question:

def check_if_image(url, image_extensions):
   if url.startswith("https://") or url.startswith("http://"):
       for extension in image_extensions:
           if(extension in url[-4:]):
               return True
   return False

def main():
   url_seed = ["http://somesite.com/img1.jpg", "https://somesite2.com/img2.gif", 
            "http://somesite3.net/img3.png", "http://noimagesite.com/noimage"]
   image_extensions = [".jpg", ".png", ".gif"]

   final_result=[]
   for site in url_seed:
       if check_if_image(site, image_extensions):
           final_result.append('<img src="%s">' %site)
   print(final_result)

This includes "http" and "https" site verification, as well as code working for 3 character image extensions, such as you asked: jpg, gif and png.

Hope it helped. Feel free to ask if you have any question.

Edit: Didn't notice you had not the urls already in a data structure, so this is invalid to your situation

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6 Comments

You can use startswith(http) or startswith(https) in check_if_image. It's faster than a regex and it's a good way to.
Thank you for the feedback. Since I'm switching languages a lot I don't always know the built-ins of them. Will take note :)
Python is great language. But regex is little bit slower than built-in function. But sometime you can take an other way than regex :D
Already updated my answer according to your tip, even if it's not the solution for this answer, but might help someone else with a similar question when googling. Thank you
My URLS are in a string like "Hi, my name is Clement and my avatar is image.jpg and there is another picture : image2.png.
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