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firstidx, 'array of arrays'

orange
User

Nov 26, 2012, 2:46 AM

Post #1 of 3 (2886 views)

firstidx, 'array of arrays'	Can't Post

I have a 'two dimensional array' and need to find the index (row number) of an element in column.

I've tried this:

Code

 my $index= firstidx { $_ eq '7' } @servces[][1];

but it doesn't work. Can you please help me?

Chris Charley
User

Nov 26, 2012, 11:48 AM

Post #2 of 3 (2866 views)

Re: [orange] firstidx, 'array of arrays' [In reply to]	Can't Post

Code

my $index= firstidx { $_->[1] == 7 } @servces;

(This post was edited by Chris Charley on Nov 26, 2012, 11:49 AM)

BillKSmith
Veteran

Nov 26, 2012, 11:55 AM

Post #3 of 3 (2864 views)

Re: [orange] firstidx, 'array of arrays' [In reply to]	Can't Post

Strictly speaking, perl does not support multi-dimensional arrays. Proper use of references largely hides this fact.

In your case, the symbol @services refers to a single dimensional array. Each element of that array is a reference. Each reference refers to a list of scalars (one "row" in your notation). The data that you think of as 'column 1" consists of the second (indexes start with zero) element of each of these arrays. To treat that colulmn as a list, you must explicitly extract it.

Code

my @col1 = map ($_->[1]) @services; 
my $index= firstidx { $_ eq '7' } @col1;

Update: Chris Charley neatly combined these two statements into one.
Good Luck,
Bill

(This post was edited by BillKSmith on Nov 26, 2012, 9:16 PM)

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