perl-data-structures

I need to convert a flat list of keys into a nested hash, as follow: my $hash = {}; my @array = qw(key1 key2 lastKey Value); ToNestedHash($hash, @array); Would do this: $hash{'key1'}{'key2'}{'lastKey'} = "Value"; Axeman sub to_nested_hash { my $ref = \shift; my $h = $$ref; my $value = pop; $ref = \$$ref->{ $_ } foreach @_; $$ref = $value; return $h; } Explanation: Take the first value as a hashref Take the last value as the value to be assigned The rest are keys. Then create a SCALAR reference to the base hash. Repeatedly: Dereference the pointer to get the hash (first time) or autovivify the

I'm quite new to Perl and I'm trying to build a hash recursively and getting nowhere. I tried searching for tutorials to dynamically build hashes, but all I could find were introductory articles about hashes. I would be grateful if you point me towards the right direction or suggest a nice article/tutorial. I'm trying to read from a file which has paths in the form of one/two/three four five/six/seven/eight and I want to build a hash like VAR = { one : { two : { three : "" } } four : "" five : { six : { seven : { eight : "" } } } } The script I'm using currently is : my $finalhash = {}; my

I am considering this answer which uses a single array reference of points, where a point is a reference to a two-element array. My original code of the question (function extract-crossing ) uses two separate arrays $x and $y here which I call like this: my @x = @{ $_[0] }; my @y = @{ $_[1] }; ... return extract_crossing(\@x, \@y); The new code below based on the answer takes (x, y) and returns a single datatype, here x intercept points: use strict; use warnings; use Math::Geometry::Planar qw(SegmentLineIntersection); use Test::Exception; sub x_intercepts { my ($points) = @_; die 'Must pass at

Possible Duplicate: What are the common workarounds for multi-line comments in Perl? How do I add a multi-line comment to Perl source code? Nikhil Jain POD is the official way to do multi line comments in Perl, see Multi-line comments in perl code and Better ways to make multi-line comments in Perl for more detail. From faq.perl.org[ perlfaq7 ] How can I comment out a large block of Perl code? The quick-and-dirty way to comment out more than one line of Perl is to surround those lines with Pod directives. You have to put these directives at the beginning of the line and somewhere where Perl

How can I maintain the order of actual list after counting its occurrence using a hash in the following program? For example, <DATA> are a b e a c d a c d b etc. Using hash, i counted the occurrence of each element. and what i want is: a 3 b 2 e 1 c 2 d 2 but the following program shows me otherwise. my (%count, $line, @array_1, @array_2); while ($line = <DATA>) { $count{$line}++ if ( $line =~ /\S/ ); } @array_1 = keys(%count); @array_2 = values(%count); for(my $i=0; $i<$#array_1; $i++) { print "$array_1[$i]\t $array_2[$i]"; } Hashes are not ordered, but as usual, CPAN offers a solution: Tie: