基于字段的哈希值（键值）Perl的最大值

Question

我想根据字段值在哈希中获取最大值，首先我通过指定键和值将每一行放在哈希中，我要排序的哈希值，并在文件上打印有基于密钥的最大值和val_dens行领域：

我的CSV文件是这样的：

date;name;type;ref;val_dens;val_number;val_tech;rate 
08.18.2017;FBT;F13;G45G6;44.19;21.11;78.21;42 
08.18.2017;FBT;F13;G45G6;55.39;24.14;56.22;32 
08.18.2017;FRT;B14;KY5F6;0.19;27.23;77.27;62 
08.18.2017;FBT;F13;G45G6;11.91;26.16;36.21;72 
08.18.2017;FBR;F12;561G6;12.51;21.13;76.2;18 
08.18.2017;FBR;F12;561G6;27.65;21.11;71.7;27 
08.18.2017;FBR;F12;561G6;9.15;18.21;77.1;11 
08.18.2017;FRT;B14;KY5F6;0.65;24.14;75.21;52 
08.18.2017;FRT;B14;KY5F6;0.14;27.11;74.12;12 
08.18.2017;FBT;F13;G45G6;14.54;62.18;16.24;52 
08.18.2017;FBR;F12;561G6;11.18;17.12;73.4;18 
08.18.2017;FBR;F12;561G6;25.12;15.23;72.5;17 
08.18.2017;FRT;B14;KY5F6;0.25;26.67;72.26;72 
08.18.2017;FBT;F13;G45G6;22.39;52.14;26.25;12 
08.18.2017;FBT;F13;G45G6;11.42;82.19;76.21;32 

我的预期输出是：

date;name;type;ref;val_dens;val_number;val_tech;rate 
08.18.2017;FBR;F12;561G6;27.65;21.11;71.7;27 
08.18.2017;FBT;F13;G45G6;55.39;24.14;56.22;32 
08.18.2017;FRT;B14;KY5F6;0.65;24.14;75.21;52 

我的代码是：

#!C:\Perl64\bin\perl.exe 
use strict; 
use warnings; 
my %linearray; 
my %index; 
open my $info "C:\\my_file.csv" or die "Could not open input file: $!"; 
while(my $line = <$info>) { 
    my @array2 = split(/;/, $line); 
    @index{@array2} = (0..$#array2); 
    my $key_date = $array2[$index{"date"}]; # first key 
    my $key_name = $array2[$index{"name"}]; # second key 
    my $key_type = $array2[$index{"type"}]; # third key 
    my $key_ref = $array2[$index{"ref"}]; # fourth key 
    my $val_dens = $array2[$index{"val_dens"}]; #first value 
    my $val_number = $array2[$index{"val_number"}]; #second value 
    my $val_tech = $array2[$index{"val_tech"}];  #third value 
    my $val_rate = $array2[$index{"rate"}]; #fourth value 

    if (not defined $key_date or not defined $key_name or not defined $key_type or not defined $key_ref){ 
     next ; 
     }  
    #ignore header of file 
    next if ($. == 1); 
# ADD line to hash 

    $linearray{$key_date.";".$key_name.";".$key_type.";".$key_ref} = $val_dens.";".$val_number.";".$val_tech.";".$val_rate 

} 
    open(my $fh, '>', 'C:\\output.csv') or die "Could not open file 'C:\\output.csv' $!"; 
    # print header 
    print $fh "date;name;type;ref;val_dens;val_number;val_tech;rate"."\n"; 
    # sort and print the max value based on val_dens field 

foreach my $Value (sort keys %linearray) { 
     print $fh "$Value;$linearray{$Value}\n"; 

} 

感谢

Answer 1

use Text::CSV_XS qw(); 

my $qfn_in = "C:\\my_file.csv"; 
my $qfn_out = "C:\\output.csv"; 

open(my $fh_in, '<', $qfn_in); 
    or die("Can't open \"$qfn_in\": $!\n"); 

open(my $fh_out, '>', $qfn_out); 
    or die("Can't create \"$qfn_out\": $!\n"); 

my $csv = Text::CSV_XS->new({ 
    auto_diag => 2, 
    binary => 1, 
    sep_char => ';', 
}); 

$csv->header($fh_in); 

my %data; 
while (my $row = $csv->getline_hr($fh_in)) { 
    my $key = join(';', @$row{qw(date name type ref)}); 
    $data{$key} = $row 
     if !exists($data{$key} 
     || $data{$key}{val_dens} < $row->{val_dens}; 
} 

my @output_cols = qw(date name type ref val_dens val_number val_tech rate); 
$csv->say($fh_out, \@output_cols); 

for my $row (values(%data)) { 
    $csv->say($fh_out, [ @$row{@output_cols} ]); 
}