Re: [Omaha.pm] perl

[Jay Hannah <jay@jays.net>]

On Apr 25, 2012, at 9:11 PM, Klinkebiel, David L wrote:
> Jay, Why do you have the | separator for chr9-10 in your perl?
> 
> my %parts = ( 
>   1 => qr/^chr[1-2]$/,
>   2 => qr/^chr[3-4]$/,
>   3 => qr/^chr[5-6]$/,
>   4 => qr/^chr[7-8]$/,
>   5 => qr/^chr(9|10)$/,
>   6 => qr/^chr1[1-2]$/,
>   7 => qr/^chr1[3-4]$/,
>   8 => qr/^chr1[5-6]$/,
>   9 => qr/^chr1[7-8]$/,

The code above doesn't make much sense.  (I should know since apparently I wrote it :)   Here's some info about Perl regular expressions:


Square brackets are sets of characters. Like [aeiouy] for "any vowel." Dashes let you specify a range. 

So [1-2] says "any single character in the ASCII chart between 1 and 2, inclusive."

[12] says "any single character, either 1 or 2."

[21] says "any single character, either 2 or 1."

So those 3 all do the exact same thing. Only "1" or "2" match. 

Usually ranges (dashes) are used for larger ranges. e.g.: [a-y] means "any lower case letter except "z". 


Parens and pipes let you have give options of varying lengths. Like (apple|pear|dog).

So (9|10) means "9" or "10". 


Does that help?

Cheers,

j