Read file, map all lines, sort results and display top 25

this example from a Well House Consultants training course
More on this [link]

This example is described in the following article(s):
• Mapping an array / list without a loop - how to do it in Perl 6 - [link]
• Sorting by key or by comparator - Perl 6 - [link]

This example references the following resources:
http://www.wellho.net/data/rstats2015.xyz
http://www.wellho.net/data/rstats2015.txt

Source code: mapper Module: P600

#!/usr/bin/env perl6

# Read file, map all lines, sort results and display top 25

# Data file can be downloaded from http://www.wellho.net/data/rstats2015.xyz
# or from http://www.wellho.net/data/rstats2015.txt ... be careful not to
# convert tabs to spaces as the program relies on a tab seperated file!

sub getGrowth($text) {
        my @fol = $text.split("\t");
        my $pg = 1.0;
        $pg = @fol[*-1] / @fol[7] unless "NULL" ~~ @fol[*-1] | @fol[7];
        (@fol[1],@fol[2],@fol[7],@fol[*-1],$pg)
        }

my @stations = slurp("rstats2015.txt").chomp.split("\n");
my @opposite = @stations>>.&getGrowth;

@opposite = @opposite.sort({@$^a[4]});

for @opposite[0..25] -> @record {
        say @record.join(", ")
}

=finish

WomanWithCat:perl6 grahamellis$ perl6 mapper
ELO, NG19 9LH, 1310, 88 , 0.067176
LLA, LL42 1AZ, 16198, 1964 , 0.121250
ACK, NE65 4DE, 917, 206 , 0.224646
HEL, DN14 0QN, 714, 182 , 0.254902
CUA, IV27 4ET, 2016, 530 , 0.262897
COE, PL14 7LL, 96, 26 , 0.270833
PIL, BS35 4JT, 245, 68 , 0.277551
GTN, CF11 8UY, 601025, 182814 , 0.3041704
PEG, NE61 6SJ, 3564, 1114 , 0.312570
ABH, LL53 6PJ, 1038, 326 , 0.314066
LEL, TR26 3DS, 8697, 2874 , 0.330459
DNY, YO21 2JL, 23729, 8440 , 0.355683
ISP, OX5 3ED, 18988, 6858 , 0.361175
CLI, M27 8LL, 417, 152 , 0.364508
WBD, DN14 0HH, 1852, 676 , 0.365011
IBM, PA16 0XB, 128741, 47376 , 0.3679947
SWO, CT15 4JH, 18282, 6822 , 0.373154
TPC, PE24 4NL, 738, 284 , 0.384824
GFF, CF81 8LT, 8997, 3606 , 0.400800
CPN, EX37 9DZ, 472, 192 , 0.406780
ADM, CT3 3JE, 53898, 22374 , 0.415117
TEA, DL2 1NL, 74, 32 , 0.432432
WOS, WR4 9EJ, 1355790, 595402 , 0.4391550
BMF, HU15 1RQ, 2912, 1304 , 0.447802
BAV, DN19 7ET, 3521, 1638 , 0.465209
ECS, NR16 2JG, 2358, 1098 , 0.465649
WomanWithCat:perl6 grahamellis$

Learn about this subject

This module and example are covered as required on private courses. Should you wish to cover this example and associated subjects, and you're attending a public course to cover other topics with us, please see our extra topic program.

Books covering this topic

Yes. We have over 700 books in our library. Books covering Perl are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples

This example comes from our "this" training module. You'll find a description of the topic and some other closely related examples on the "this" module index page.

Full description of the source code

You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources

• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
• The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

Purpose of this website

This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

Web site author

This web site is written and maintained by Well House Consultants.

Conditions of use

Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request.