Re: Why doesn't this regex work?

Have you tried

use re 'debug';
[download]

Its output is very long, but as you know what the regex should do, you might understand it.

Update: It seems your example data miss a digit at the end of each number. I tried it with a different data:

2120 2140 2180 2197 2200 2203 2205 2234 2238 2259 2280 2299 2401
[download]

If I understood your specification, the following should do the work, being a bit more readable:

    s/\b(\d*)(\d\d) (?=\1\d\d\b)/$1$2_/g;
    s/ /\n/g;
    s/_/ /g;
[download]

لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

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Re^2: Why doesn't this regex work? by BrowserUk (Patriarch) on Aug 15, 2013 at 10:11 UTC
Have you tried `use re 'debug';` Yes. But it didn't help. It shows that matches do occur; but doesn't explain why the newlines are never inserted. It seems your example data miss a digit at the end of each number. My mistake trying to simplify the data. Two corrections are possible: Remove one \d from each side of the regex: `while( <DATA> ) { s[\s(\d+)\d\K\s(?=(\d+)\d\s)]{ print "$1:$2"; $1 + 1 == $2 ? "\n" : ' ' }ge; print; }` [download] Add a digit to the end of each number in the data: `1051 1061 1071 1081 1091 1101 1111 1121 1131 11151 11161 11171 11181 11191 11201 11211 11221 11231 123451 123461 123471 123481 123491 123501 123511 123531` [download] as you know what the regex should do The idea of the regex is to match each pair of numbers in a line and capture the first d-2 digits of each number. Eg. Match the pair and capture the first two digits of each: `(10)91 (11)01`. Then if $1+1 (10+1) == $2 (11) replace the space between them with a newline. The \K prevents the number before the replaced space being replaced. And the lookahead prevents the number after ebing replaced. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]

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Re^2: Why doesn't this regex work?
by BrowserUk (Patriarch) on Aug 15, 2013 at 10:11 UTC

Have you tried use re 'debug';

Yes. But it didn't help. It shows that matches do occur; but doesn't explain why the newlines are never inserted.

It seems your example data miss a digit at the end of each number.

My mistake trying to simplify the data. Two corrections are possible:

Remove one \d from each side of the regex:

while( <DATA> ) {
    s[\s(\d+)\d\K\s(?=(\d+)\d\s)]{
        print "$1:$2";
        $1 + 1 == $2 ? "\n" : ' '
    }ge;
    print;
}
[download]

Add a digit to the end of each number in the data:

1051 1061 1071 1081 1091 1101 1111 1121 1131
11151 11161 11171 11181 11191 11201 11211 11221 11231
123451 123461 123471 123481 123491 123501 123511 123531
[download]

as you know what the regex should do

The idea of the regex is to match each pair of numbers in a line and capture the first d-2 digits of each number.

Eg. Match the pair and capture the first two digits of each: (10)91 (11)01.

Then if $1+1 (10+1) == $2 (11) replace the space between them with a newline.

The \K prevents the number before the replaced space being replaced. And the lookahead prevents the number after ebing replaced.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

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