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Re^6: regular expessions question: (replacing words)

by $new_guy (Acolyte)
on Sep 28, 2010 at 07:28 UTC ( #862363=note: print w/replies, xml ) Need Help??

in reply to Re^5: regular expessions question: (replacing words)
in thread regular expessions question: (replacing words)

Hi Jethro,

Thanks for the explanation!

Yes the data fits in memory! And yes it would be appropriate to say every z is 1 and non-z is 0.

I still don't understand! How do I select two columns at random, then count only the z's that are common to all rows in the two columns. By count I meant if a z occurs in column 1 at row 6 and column 2 at row six then my count of z's would be 1. Notice my count will increase as I go down comparing the rows.

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Re^7: regular expessions question: (replacing words)
by jethro (Monsignor) on Sep 28, 2010 at 22:44 UTC

    That with the 0 and 1 would only have been necessary if you needed to compress the data , i.e. save memory. Which you say isn't the case.

    Ok, here is the subroutine that counts rows with all 'z' in specific columns:

    sub countrows { # First parameter is a pointer/reference to the data # Second parameter is an array of columns numbers my ($data,@f)= @_; my $count=0; foreach my $row (@$data) { my $success=1; foreach (@f) { if ($row->[$_] ne 'z') { $success=0; last; } } $count+= $success; } return $count; } my @data= ( ['z',4,'z',4,'z'],['z',4,'z',4,4],['z','z','z',4,'z'] ); print countrows(\@data,0,2),' ',countrows(\@data,1,3,2),' ',countrows( +\@data,4),"\n"; # print 3 0 2

    Now to get an array of random numbers. To make sure I don't get numbers twice I generate an array of all numbers up to the number of columns and pick (i.e. extract and delete) random numbers from that array

    sub randomarray { my ($columns,$count)= @_; my @all; push @all, $_ foreach (0..($columns-1)); my @randarray; while ($count-- >0) { push @randarray, splice(@all, int(rand(@all)),1); } return @randarray; } print join ' ',randomarray( scalar @{$data[0]} , 2 ),"\n"; print join ' ',randomarray( scalar @{$data[0]} , 3 ),"\n"; print join ' ',randomarray( scalar @{$data[0]} , 4 ),"\n"; # might print 3 4 3 0 1 0 1 4 2

    You see how I cut the problem into smaller pieces that are easier to tackle? Ok, the subroutines are still not trivial. But you should be able to connect them in a sensible way to solve your problem

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