Using regex to parse a delimited array in bash - regex

Question

I have a file that contains the following line:
<polyline id="graph" points="0,287 100,470 200,509 300,459 400,471"/>
And I need to extract the following values:
287 470 509 459 471
I am currently using this code:
grep -oP '(?<=points=").*(?="/>)' "file.svg" | grep -oP '(?<=,)[[:digit:]]*'
I want to do it with a single grep, I tried using (?:), with no success. Any suggestions?

Answer 1

A sed solution can be like
$ sed -r '/points=/ s/[^,]+,?([0-9]*)/\1 /g' input
287 470 509 459 471
OR
for much better handling
$ sed -r '/points=/ s/.*points=("[^"]+").*/\1/g; s/[^,]+,?([0-9]*)/\1 /g' input
287 470 509 459 471

Answer 2

If you're just parsing a single line like that, you might get away with using XML::Simple, like this:
perl -MXML::Simple -lwe'$x = XMLin(<>); print $x->{points};' file.svg
With your line, this gives me the following output:
0,287 100,470 200,509 300,459 400,471
The entire structure in $x parsed from that line looks like this when printed with Data::Dumper:
$VAR1 = {
'points' => '0,287 100,470 200,509 300,459 400,471',
'id' => 'graph'
};
Note that you may need to pre-process your input, if it is more complex than you indicated in your question.

Answer 3

It's XML, so parse as XML.
use XML::Twig;
my $twig = XML::Twig -> new -> parse ( '<polyline id="graph" points="0,287 100,470 200,509 300,459 400,471"/>' );
print $twig -> root -> {'att'} -> {'points'};
Although - you might need something slightly different if you want to parse it out of a svg file - but you can then use $twig -> parsefile.
Simplifies as a one liner:
perl -MXML::Twig -e 'print XML::Twig -> new -> parsefile ("test.xml" ) -> root -> first_child("polyline") -> {"att"}{"points"};'

Answer 4

You can use gnu-awk:
awk -v RS='points="[^"]+"' 'RT{s=RT; gsub(/[^[:digit:], ]|[[:digit:]]+,/, "", s);
print s}' file
287 470 509 459 471

Answer 5

This awk should do:
awk -F\" '/points/ {gsub(/[0-9]+,/,"",$4);print $4}' file
287 470 509 459 471
If position on the line do change, do:
awk -F"points=" 'NF==2{gsub(/[0-9]+,|[^0-9 ]/,"",$2);print $2}' file
287 470 509 459 471