RegularExpression python

Asked Sep 02 '16 at 13:35

Active Sep 02 '16 at 13:37

Viewed 26 times

I read the Oreilly book about python scraping the in chapter 3, page 41 the author using regular expression to take all link begin with "/" .She wrote:

for link in bsObj.findAll("a", href=re.compile("^(/|.*"+includeUrl+")")):
        if link.attrs['href'] is not None:
            if link.attrs['href'] not in internalLinks:
                if(link.attrs['href'].startswith("/")):
                    internalLinks.append(includeUrl+link.attrs['href'])
                else:
                    internalLinks.append(link.attrs['href'])
    return internalLinks

I dont know why "begin with /" write like this? Because in regex before start a special symbol like "/" we will write like "/" and what the "|" (or) in it mean? Please help me to explain it. Thank alot!!!

edited Sep 02 '16 at 13:37

asked Sep 02 '16 at 13:35

AlphaWolf

http://stackoverflow.com/questions/22937618/reference-what-does-this-regex-mean ? Use http://regex101.com to see what a pattern means. – Wiktor Stribiżew Sep 02 '16 at 13:37
by using regex101, it does not explain the symbol "|" :( – AlphaWolf Sep 02 '16 at 13:57
See https://regex101.com/r/mV7aS6/1: *1st Alternative: `/`*, *2nd Alternative: `.*includeUrl`*. It is *alternation* operator. – Wiktor Stribiżew Sep 02 '16 at 13:59
ok, i got it, but why before a special symbol "/" do not have "\"? – AlphaWolf Sep 02 '16 at 14:01
I already wrote: *It is alternation operator.* Either this OR that. – Wiktor Stribiżew Sep 02 '16 at 14:05
yes yes i.got it, thank you very much :) – AlphaWolf Sep 02 '16 at 14:08

RegularExpression python

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