Re: In-place regex substitution

To demo one idea from LanX, with the 'e', execute option on the regex, arbitrary code can be executed. I coded the idea of using sprintf(). The code below will round to 6 decimal places instead of truncating at 6 decimal places.

Example:

47.488539642204628
truncates to: 47.488539
rounds to:    47.488540
[download]

use warnings;
use strict;

my $content = '{ "geometry": { "type": "Polygon", "coordinates": [ [ [
+ 19.054804912278406, 47.485785556135411 ], [ 19.057857836771483, 47.4
+87322542030711 ], [ 19.06025597925397, 47.488491565765209 ], [ 19.060
+347248086835, 47.488539642204628 ], [ 19.060463310421543, 47.48457828
+7406251 ], [ 19.054804912278406, 47.485785556135411 ] ] ] } }';

$content =~ s/(\d\d\.\d*)/sprintf("%.6f",$1);/ge; #round to 6 decimal 
+digits
print "$content\n";

__END__
Truncated:
{ "geometry": { "type": "Polygon", "coordinates": [ [ [ 19.054804, 47.
+485785 ], [ 19.057857, 47.487322 ], [ 19.060255, 47.488491 ], [ 19.06
+0347, 47.488539 ], [ 19.060463, 47.484578 ], [ 19.054804, 47.485785 ]
+ ] ] } }

Rounded:
{ "geometry": { "type": "Polygon", "coordinates": [ [ [ 19.054805, 47.
+485786 ], [ 19.057858, 47.487323 ], [ 19.060256, 47.488492 ], [ 19.06
+0347, 47.488540 ], [ 19.060463, 47.484578 ], [ 19.054805, 47.485786 ]
+ ] ] } }
[download]

Comment on Re: In-place regex substitution Select or Download Code

Replies are listed 'Best First'.
Re^2: In-place regex substitution by AnomalousMonk (Archbishop) on Dec 10, 2016 at 15:49 UTC
`$content =~ s/(\d\d\.\d)/sprintf("%.6f",$1);/ge; #round to 6 decimal +digits` [download] One can avoid hard-coding the rounding precision by using either `my $n = $some_integer;` `... sprintf("%.${n}f", $1) ...` or the "wildcard" (if that's the right term (update:* maybe "placeholder"?)) format specifier `... sprintf('%.f', $n, $1) ...` Update:* In the code above, I've implied that `$n` must be an integer. Interestingly (for some definition of "interesting"), if it is not, then the first code example (`$n` interpolated) screws up, but the second (`*` wildcard specifier) behaves "properly", DWIMishly ignoring the fractional part of the numeric value. (I haven't checked yet to see if this behavior is the same as in C/C++/D/etc.) Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re^2: In-place regex substitution by LanX (Saint) on Dec 10, 2016 at 15:36 UTC
Thanks, but a minor nitpick. :) > `s/(\d\d\.\d)/`* this will exclude numbers smaller than ten (already so in marto's post) Supposing all numbers have a decimal point, I'd say `s/(\d+\.\d*)/` It's really hard to guess which formats are possible and where they'll appear. In the end the safest way is use a JSON parser. Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :) Je suis Charlie!}	[reply] [d/l] [select]