Perl - write data from hashes

Perlseeker_1 has asked for the wisdom of the Perl Monks concerning the following question:

Hi Experts,

I need help on perl hashes.i have used hashes to store the data. i have fetched data from four files and stored data in hashes.

key and value pair, code written to fetch data and store in hashes

I have created four sub routines for file 1,file 2, file 3 and file 4, the key which i formed for each file will vary

for file 1 --> $key = f[0].f1,file 2 --> f1.f2,file 3 --> $key = f4.f6,file 4 --> $key = f3.f4

code for file 1

my (%r1,%r2,%r3,%r4);
my $Total;

foreach my $file (@files) {
open FILE, "<$dir/$file" or warn "Couldn't open file ($!) or file ($!)
+ not found\n";
while (chomp ( my @fields = split /\t/, <FILE>) ) {    
my $key = "$f[0].$f[1]";
if ($c{$key}) {
$key = $c{$key};
if (exists($r1{$key})){
$r1{$key} += $f[02];
}
else { 
$r1{$key} += $f[02];
}
$Total +=$r1{$key};
}
}
$r1{'Total'} = $Total;
}
close FILE;
[download]

Example input file 1

A B 12.00
C D 13.00
E F 11.00
G H 22.00
[download]

code for file 2

foreach my $file (@files) {
open FILE, "<$dir/$file" or warn "Couldn't open file ($!) or file ($!)
+ not found\n";
while (chomp ( my @fields = split /\t/, <FILE>) ) {    
my $key = "$f[1].$f[2]";
$key{'Output - Final'}=1;
if ($c{$key}) {
$key = $c{$key};
if (exists($r1{$key})){
$r1{$key} += $f[03];
}
else { 
$r1{$key} += $f[03];
}
$Total +=$r1{$key};
}
}
$r1{'Total'} = $Total;
}
close FILE;
[download]

Example input file 2

1 A B 12.00
2 C D 13.00
3 E F 11.00
4 G H 22.00
[download]

Output got

r1 --> hash contains data as ...
Key    Value

Name    F1.A
AB    12.00
CD    13.00
EF    11.00
GH    22.00

r2 --> hash contains data as ...
Key    Value

Name    F2.B
AB    01.00
CD    04.00
EF    42.00
GH    34.00

r3 --> hash contains data as ...
Key    Value

Name    F3.C
AB    02.00
CD    03.00
EF    15.00
GH    20.00

r4 --> hash contains data as ...
Key    Value

Name    F4.D
AB    62.00
CD    43.00
EF    24.00
GH    26.00
[download]

Output expected

Output - Final
    Name    F1.A    F2.B    F3.C    F4.D
    AB    12.00    01.00    02.00    62.00    
    CD    13.00    04.00    03.00    43.00
    EF    11.00    42.00    15.00    24.00
    GH    22.00    34.00    20.00    26.00

Total    58.00    81.00    40.00    155.00
[download]

Thanks

Comment on Perl - write data from hashes Select or Download Code

Replies are listed 'Best First'.
Re: Perl - write data from hashes by aitap (Curate) on Oct 13, 2013 at 15:24 UTC
Are the keys in all the hashes always the same? If yes, here's an algorythm for you: Get the list of keys from any of the hashes, possibly sort it or make the `Name` key first somehow For each of the keys you got, print its name, then (joined by `"\t"` between them) its values from your collected hashes You'll probably want to use an array of hashes (read perlreftut and perldsc for more info) instead of just a bunch of numbered variables. Example code using an array of hashes (untested): `for my $key ("Name", grep { $_ ne "Name" } keys %{$hashes[0]}) { print ((join "\t", $key, map { $_->{$key} } @hashes),"\n"); }` [download] It could have been easier to print `Name` first it you didn't mix it with the other data. _{Edit: forgot to print "\n"}	[reply] [d/l] [select]
Re^2: Perl - write data from hashes by Happy-the-monk (Canon) on Oct 13, 2013 at 15:34 UTC
joined by `"\t"` between in case that turns out less then perfect, resort to printf or sprintf Cheers, Sören Créateur des bugs mobiles - let loose once, run everywhere. (hooked on the Perl Programming language)	[reply]
Re: Perl - write data from hashes by CountZero (Bishop) on Oct 13, 2013 at 17:25 UTC
This part of your code is rather strange: `if (exists($r1{$key})){ $r1{$key} += $f[02]; } else { $r1{$key} += $f[02]; }` [download] You do exactly the same whether or not the key already exists in the hash. Therefore you can replace this simply by: `$r1{$key} += $f[02];` [download] CountZero A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James My blog: Imperial Deltronics	[reply] [d/l] [select]
Re^2: Perl - write data from hashes by marinersk (Priest) on Oct 14, 2013 at 05:51 UTC
Interesting. In older versions of Perl, I encountered the issue where attempting to add a value to an undefined hash element would generate a warning. I see under my modern version of Perl, this is not an issue: #!/usr/bin/perl -w use strict; my $TEST_KEY = 'abc'; my $TEST_VAL = 5; my %TestHash = (); { print "-----[ Addition to undef ]---------------\n"; %TestHash = (); $TestHash{$TEST_KEY} += $TEST_VAL; print "-----[ Addition testing for undef ]------\n"; %TestHash = (); if (defined $TestHash{$TEST_KEY}) { $TestHash{$TEST_KEY} += $TEST_VAL; } else { $TestHash{$TEST_KEY} = $TEST_VAL; } } exit; __END__ C:\Steve\Dev\PerlMonks\P-2013-10-13@2339-HashUndef>hashtest.pl -----[ Addition to undef ]--------------- -----[ Addition testing for undef ]------ [download] I think -- not 100% sure, but I think -- I am happy about this.	[reply] [d/l]
Re: Perl - write data from hashes by Lennotoecom (Pilgrim) on Oct 13, 2013 at 20:19 UTC
Mr. aitap I tested your snippet, without modification it would give away "Modification of a read-only value attempted at" error nevertheless that snippet of yours is a beautiful code mate and here i'm using it thank you and here the complete script for the author, it processes 4 files in a loop files are named file1-4 `for ($i = 1; $i < 5; $i++){ $a[$i]{'name'} = "file$i"; open IN, "<file$i" or die $!; while(<IN>){ if (/(\w)\t(\w)\t([\d\.]+)/){ $a[$i]{"$1$2"} = $3; $a[$i]{'total'} = sprintf('%.2f', $a[$i]{'total'}+=$3) +; } } close(IN); } foreach $key ('name', grep {$_ ne 'name'} sort keys $a[1]){ print join "\t", $key, map($_->{$key}, @a[1..4]),"\n"; }` [download] and output: `name file1 file2 file3 file4 AB 12.00 01.00 02.00 62.00 CD 13.00 04.00 03.00 43.00 EF 11.00 42.00 15.00 24.00 GH 22.00 34.00 20.00 26.00 total 58.00 81.00 40.00 155.00` [download] files which are used, created from the author's output: `~@deb:~/perl/9# cat file1 A B 12.00 C D 13.00 E F 11.00 G H 22.00 ~@deb:~/perl/9# cat file2 1 A B 01.00 2 C D 04.00 3 E F 42.00 4 G H 34.00 ~@deb:~/perl/9# cat file3 A B 02.00 C D 03.00 E F 15.00 G H 20.00 ~@deb:~/perl/9# cat file4 1 A B 62.00 2 C D 43.00 3 E F 24.00 4 G H 26.00` [download]	[reply] [d/l] [select]