Swapping two parts of a string

Harch84 has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks I need your valued help again. I have a string which is passed to a perl variable from a html/javascript and returns a set of coordinates. An example of one of these coordinate strings would be this:

(55.950254, -3.187606)

Now what I need to do is to get rid of the comma in this string and then to take the first part of coordinate "55.950254" and put it in front of the other part "-3.187606". The output should look like this:

(-3.187606 55.950254)

I have managed to get rid of the comma using this command in Perl:


$origin =~ s/,//;
[download]

... but im not sure how I could swap the two strings around using perl? If it helps both parts should be exactly 9 characters long.
Thanks for your help

Comment on Swapping two parts of a string Download Code

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Re: Swapping two parts of a string by FunkyMonk (Bishop) on Jul 22, 2007 at 20:45 UTC
`my $input = "(55.950254, -3.187606)"; ( my $output = $input ) =~ s{([-\d.]+), # capture the first number to + $1 \s+ # at least one space ([-\d.]+) # capture the second to $2 } {$2 $1}x; # reverse $1 & $2 print $output;` [download] See perlre and perlretut for help with regular expressions, and Regexp Quote-Like Operators in perlop for `s///`. update: added references to documentation	[reply] [d/l] [select]
Re: Swapping two parts of a string by grep (Monsignor) on Jul 23, 2007 at 01:50 UTC
FWIW a non regex answer `my $input = "(55.950254, -3.187606)"; my $result = '('.join(' ',reverse(split(/[(),]/,$input))).')';` [download] grep	[reply] [d/l]
Re: Swapping two parts of a string by GrandFather (Saint) on Jul 22, 2007 at 20:53 UTC
Capture the two strings to be swapped using a regex then put them back together in opposite order: `$origin =~ s/$ ([^ ,]+) \s,\s ([^ )]+) $ /($2 $1)/x;` [download] Note that the /x allows the spaces to be used to break up the expression for easier understanding. DWIM is Perl's answer to Gödel	[reply] [d/l]
Re: Swapping two parts of a string by Harch84 (Acolyte) on Jul 22, 2007 at 22:37 UTC
Hey thanks for the quick replies guys they have been a big help!	[reply]
Re: Swapping two parts of a string by robot_tourist (Hermit) on Jul 23, 2007 at 12:03 UTC
I have nothing to add except: cool, the Royal Mile! How can you feel when you're made of steel? I am made of steel. I am the Robot Tourist. Robot Tourist, by Ten Benson	[reply]
Re: Swapping two parts of a string by oxone (Friar) on Jul 25, 2007 at 21:07 UTC
Here's a much worse way to do this, which is neither big or clever (although it does work): `my $input = "(55.950254, -3.187606)"; (my $result = join ' ', eval "reverse$input" ) =~ s/(.*)/($1)/;` [download] oxone \| www.datasalon.com	[reply] [d/l]