Learning Perl, Hashes Help

learningmanylang has asked for the wisdom of the Perl Monks concerning the following question:

I am learning the basics of Perl, after finishing learning the basics of Groovy, Python, C#, Scala and adding onto my Java this semester.
My main goal is to have a program read in a file that contains a number on each line like

1
2
3
3
2
2
1
2
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and take those numbers and print them out in order with a "*" mark for every occurrence, making a histogram type program. I can post my code in Java or something else if it would help anyone understand what I am talking about.
The output I need looks like:
1:**
2:****
3:**

open(FILE, '/location/data/p4.txt') or die "Cant't open file: $!\n";
my %myhash = ();
my @data = ();

chomp(@data = <FILE>);
foreach (@data)    {
    %myhash = (@data => $k++);
}

foreach $k (sort {$a <=> %b} keys %myhash)    {
    print "$myhash{$k} : ". '*' x $myhash{$k} . "\n";
}
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This is what I have done so far from using code in another problem I made. How do I up the count? It doesn't seem like my loop is working properly on this problem either.

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Re: Learning Perl, Hashes Help by toolic (Bishop) on Apr 29, 2014 at 00:56 UTC
Tip #1 from the Basic debugging checklist... warnings `use warnings; my %myhash = (); my @data = (); chomp(@data = <DATA>); foreach (@data) { $myhash{$_}++; } foreach $k (sort {$a <=> $b} keys %myhash) { print "$k : ". '*' x $myhash{$k} . "\n"; } __DATA__ 1 2 3 3 2 2 1 2` [download]	[reply] [d/l]
Re^2: Learning Perl, Hashes Help by learningmanylang (Initiate) on Apr 29, 2014 at 01:05 UTC
Awesome, I actually had it like that first, but I had $myhash{$k}++; instead of $myhash{$_}++; Perl has been like reading Chinese compared to all of the other wordier languages I'd been working with.	[reply]
Re^3: Learning Perl, Hashes Help by soonix (Chancellor) on Apr 29, 2014 at 08:19 UTC
would have worked, with `foreach $k (@data) {` [download] instead of `foreach (@data) {` [download]	[reply] [d/l] [select]
Re: Learning Perl, Hashes Help by Jim (Curate) on Apr 29, 2014 at 01:33 UTC
Instead of doing this… `open(FILE, '/location/data/p4.txt') or die "Cant't open file: $!\n +";` [download] …do this… `use strict; use warnings; use autodie qw( open close ); # ... my $file = shift; # The input file name is a command-line argument open my $fh, '<:encoding(ASCII)', $file; # Or whatever the correct + character encoding is # ... close $fh;` [download] And instead of doing this… `my %myhash = (); my @data = (); chomp(@data = <FILE>); foreach (@data) { %myhash = (@data => $k++); }` [download] …do this… `my %total_values_by; while (my $value = <$fh>) { chomp $value; $total_values_by{$value}++; }` [download]	[reply] [d/l] [select]