Beefy Boxes and Bandwidth Generously Provided by pair Networks
XP is just a number
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

G'day sroux,

Given the size of your data, processing speed may be a factor. The following may be faster than other proposed solutions; but do Benchmark with realistic data.

I've used the same input data as others have done.

$ cat pm_11140211_flatfile.dat head1|head2|head3 val1|val2|val3 val1|val4|val5 val6|val4|val5 val2|val7|val5 val3|val7|val3

My code takes advantage of the fact that when duplicate keys are used in a hash assignment, only the last duplicate takes effect. A short piece of code to demonstrate:

$ perl -e ' use Data::Dump; my %x = (a => 1, b => 3, c => 4); my %y = (b => 2, c => 3, d => 4); my %z = (%x, %y); dd \%z; ' { a => 1, b => 2, c => 3, d => 4 }

So there's no need for %seen, uniq(), or any similar mechanism, to handle duplicates.

Also note that I've used bind_columns(). See the benchmark in "Text::CSV - getline_hr()".

The code:

#!/usr/bin/env perl use strict; use warnings; use autodie; use Text::CSV; my $infile = 'pm_11140211_flatfile.dat'; my $csv = Text::CSV::->new({sep_char => '|'}); open my $in_fh, '<', $infile; my $row = {}; my @cols = @{$csv->getline($in_fh)}; $csv->bind_columns(\@{$row}{@cols}); my %data = map +($_, {}), @cols; while ($csv->getline($in_fh)) { $data{$_} = { %{$data{$_}}, $row->{$_}, 1 } for @cols; } print "$_: ", join(', ', sort keys %{$data{$_}}), "\n" for sort @cols;

The output:

head1: val1, val2, val3, val6 head2: val2, val4, val7 head3: val3, val5

— Ken


In reply to Re: Get unique fields from file by kcott
in thread Get unique fields from file by sroux

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others making s'mores by the fire in the courtyard of the Monastery: (4)
As of 2022-08-18 07:08 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found

    Notices?