Convert hash into csv file - arrays

Question

I got a hash:
%hash = (
Honda.Blue => '10',
Honda.Red => '10',
Honda.Yellow => '60',
Ford.Blue => '20',
Ford.Red => '25',
Ford.Yellow => '26',
Toyota.Blue => '17',
Toyota.Red => '16',
Toyota.Yellow => '18',
);
Need to convert this hash into a csv file with the following headers (make,blue_volume,red_volume,yellow_volume) and fill it with data
#Make,blue_volume,red_volume,yellow_volume
#Honda,10,10,60
#Ford,20,25,26
#Toyota,17,16,18
loop over %hash
#array = split('.',$key);
$make=$array[0];
$line = "$make,$hash{'$make.Blue'},$hash{'$make.Red'},$hash{'$make.Yellow'}";
push(#lines,$line);
foreach (#lines)
{
open (LOG, '>>summary.csv');
print LOG "$_";
close (LOG);
}
Need help figuring out this code.

Answer 1

First step:
use strict; says:
Bareword "Honda" not allowed while "strict subs" in use at xx.pl line 4.
That is not an approved way of creating the hash. I suggest:
use strict;
use warnings;
my %hash = (
Honda => { Blue => '10', Red => '10', Yellow => '60' },
Ford => { Blue => '20', Red => '25', Yellow => '26' },
Toyota => { Blue => '17', Red => '16', Yellow => '18' },
);
Then, you should probably use Text::CSV. However, it is not all that hard to do output with simple manipulation. We can exploit the fact that you've asked for blue, red, yellow which happen to be in alphabetic order:
print "make,blue_volume, red_volume,yellow_volume\n";
foreach my $make (sort keys %hash)
{
print "$make";
foreach my $colour (sort keys %{$hash{$make}})
{
print ",$hash{$make}{$colour}";
}
print "\n";
}
For the sample hash, the output is:
make,blue_volume, red_volume,yellow_volume
Ford,20,25,26
Honda,10,10,60
Toyota,17,16,18
If there was any risk of needing to use quotes or anything else, I'd use Text::CSV.

Answer 2

A solution with List::MoreUtils.
#!/usr/bin/env perl
use warnings;
use 5.012;
use List::MoreUtils qw/first_index/;
use Text::CSV;
my $file_out = 'my_new_file.csv';
my %hash = (
'Honda.Blue' => '10',
'Honda.Red' => '10',
'Honda.Yellow' => '60',
'Ford.Blue' => '20',
'Ford.Red' => '25',
'Ford.Yellow' => '26',
'Toyota.Blue' => '17',
'Toyota.Red' => '16',
'Toyota.Yellow' => '18',
);
my #brands = qw( Honda Ford Toyota );
my #colors = qw( Blue Red Yellow );
my #array;
for my $key ( keys %hash ) {
my( $brand, $color ) = split /\./, $key, 2;
my $idx_1 = first_index { $_ eq $brand } #brands;
my $idx_2 = first_index { $_ eq $color } #colors;
$array[$idx_1][0] = $brand;
$array[$idx_1][$idx_2+1] = $hash{$key};
}
my $csv = Text::CSV->new ( { binary => 1, eol => $/, auto_diag => 2 } )
or die Text::CSV->error_diag();
my $col_names = [ qw( Make blue_volume red_volume yellow_volume ) ];
open my $fh, '>:encoding(UTF-8)', $file_out or die $!;
$csv->print ( $fh, $col_names );
$csv->print ( $fh, $_ ) for #array;
close $fh;

Answer 3

If you iterate over the hash and make a line for each key, you will have each make repeated three times; instead, create another hash with all the makes by looping over %hash, extracting the make, and setting $makes{$make} = 1. Then loop over that to produce your lines.
When you extract the make from the %hash key, use /\./ as the split pattern; split always uses a pattern, not a simple string (with one odd exception), and you don't want to split on every character, which is what split '.' would do (thanks, codaddict, for pointing this part out).
'$make.Blue' uses single quotes, so it won't interpolate the variable. Use "$make.Blue" instead.
Move the open and close to before and after the #lines loop, respectively. There's no reason to open the file for each line.
Don't forget a "\n" at the end of each line (unless you are using the -l flag or say instead of print).

Answer 4

Check out Text::CSV::Slurp. It will allow you to turn a hash into CSV and vice versa as well.

Answer 5

For those interested I was able to figure it out, thanks for everyone's help!
my %hash;
$hash{'aaa.biz'} = 'domainRegistered';
$hash{'aaa.com'} = 'domainRegistered';
$hash{'aaa.info'} = 'domainRegistered';
$hash{'aaa.net'} = 'domainRegistered';
$hash{'aaa.org'} = 'domainRegistered';
$hash{'bbb.biz'} = 'domainRegistered';
$hash{'bbb.com'} = 'domainRegistered';
$hash{'bbb.info'} = 'domainRegistered';
$hash{'bbb.org'} = 'domainRegistered';
$hash{'bbb.us'} = 'domainRegistered';
foreach $key (sort keys %hash)
{
#array=split("\\.",$key);
push (#names, $array[0]);
}
#Extract unique values and sort
my %seen = ();
my #result = grep { !$seen{$_}++ } #names;
#names = sort { $a <=> $b } #result;
foreach $element (#names)
{
foreach $key (sort keys %hash)
{
#array=split("\\.",$key);
if (#array [0] eq $element){push (#values, $hash{$key});}
}
$values = join(",",#values);
$line = "$element,$values";
undef #values;
push(#lines,$line);
}
print join("\n",#lines);
open (summary, '>>summary.csv');
print summary join("\n",#lines);
close (summary);