Adding an element to an array

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

Hi Monks!

I am trying to count how many "houses" each person has once I get the data from the database, I included a data sample so you can see better what I am trying to do.
I tried the way I have in this sample code here but it isn’t working.
Any suggestions on how I could do this?
Sample code:


#!/usr/bin/perl  
 
use strict;
use warnings;
use Data::Dumper;

...

 my @all_profile;
 my %homes_by_names;

 foreach my $row ( @{ $sql } ) {
    
     my %profile;
         
     $profile{ NAME } = $row->{'name'};
     $profile{ ADDRESS } = $row->{'address'};
     $profile{ HOME } = $row->{'home'};
     
     # I will need to count the how many homes here
     push ( @{ $homes_by_names{$profile{ HOME } } }, \%profile);
     
     push @all_profile, { 'HOME COUNT' => scalar @{ $homes_by_names{HO
+ME} };
     
     push @all_profile, \%profile;
     
 }

 print Dumper \@all_profile;

$VAR1 = [
      {
        'NAME' => 'John Doe',
        'ADDRESS' => 'Main Street',
        'HOME' => 'House 1',
        'HOME COUNT' => '3',
      },
      ...


=data
# Sample data to show how I need to count how many Houses per person
John Doe, Main Street, House 1
John Doe, Main Street, House 1
John Doe, Main Street, House 1
Mary Lou, Central Street, House 1
Mary Lou, Central Street, House 1
Mary Lou, Central Street, House 1
Mary Lou, Central Street, House 1
Jane B,.  Squere Rd., House 1
Maria D., Pat street, House B
Maria D., Pat street, House B
[download]

Thanks for looking!!!

Comment on Adding an element to an array Download Code

Replies are listed 'Best First'.
Re: Adding an element to an array by AppleFritter (Vicar) on Oct 14, 2015 at 18:51 UTC
If you're pulling data from an SQL database, the best approach may be to let the database do the work for you; SQL has a `COUNT` aggregate function. Something along the following lines, perhaps: SELECT Name, COUNT(Home) AS HomeCount FROM People GROUP BY Name;	[reply]
Re^2: Adding an element to an array by Anonymous Monk on Oct 14, 2015 at 19:24 UTC
Unfortunately I cant use the database for this one, since it is already too complex, I need to try using Perl.	[reply]
Re^3: Adding an element to an array by Pope-O-Matik (Pilgrim) on Oct 14, 2015 at 23:56 UTC
There are plenty of ways to unobtrusively change the statement already being used. Can you show us the SQL statement used to pull the data?	[reply]
Re: Adding an element to an array by poj (Abbot) on Oct 14, 2015 at 19:30 UTC
#!/usr/bin/perl use strict; use warnings; use Data::Dumper; my @all_profile; my %homes_by_names; while (<DATA>){ chomp; my @f = split ',',$_; my %profile; $profile{ NAME } = $f[0];#$row->{'name'}; $profile{ ADDRESS } = $f[1];#$row->{'address'}; $profile{ HOME } = $f[2];#$row->{'home'}; # I will need to count the how many homes here ++$homes_by_names{ $profile{ NAME } }; push @all_profile, \%profile; } for (@all_profile){ $_->{'HOME COUNT'} = $homes_by_names{ $_->{ NAME } }; } print Dumper \@all_profile; __DATA__ John Doe, Main Street, House 1 John Doe, Main Street, House 1 John Doe, Main Street, House 1 Mary Lou, Central Street, House 1 Mary Lou, Central Street, House 1 Mary Lou, Central Street, House 1 Mary Lou, Central Street, House 1 Jane B,. Squere Rd., House 1 Maria D., Pat street, House B Maria D., Pat street, House B [download] poj	[reply] [d/l]
Re^2: Adding an element to an array by Anonymous Monk on Oct 15, 2015 at 15:30 UTC
Hi! I am trying to use your code but I am getting this error: `Error: Global symbol "%row" requires explicit package name at...` My data structure is like this: `[ [ "John Doe", "Main Street", "House 1", ], [ "John Doe", "Main Street", "House 1", ], ... ]` [download] Trying to apply your code in here: `my %homes_by_names; foreach my $row ( @data ) { $row{'HOME_COUNT'} = $homes_by_name{ $row{ HOME } }; }` [download] Thanks for looking!	[reply] [d/l] [select]
Re^3: Adding an element to an array by NetWallah (Canon) on Oct 15, 2015 at 15:40 UTC
$row is a hashref. Try: `$row->{'HOME_COUNT'} = $homes_by_name{ $row->{ HOME } };` [download] Software efficiency halves every 18 months, thus compensating for Moore's Law.	[reply] [d/l]
Re^4: Adding an element to an array by Anonymous Monk on Oct 15, 2015 at 15:54 UTC
Re^5: Adding an element to an array by poj (Abbot) on Oct 15, 2015 at 16:12 UTC
Some notes below your chosen depth have not been shown here
Re^2: Adding an element to an array by Anonymous Monk on Oct 14, 2015 at 19:43 UTC
Its getting there, I am getting an error as: `Can't use string ("3") as an ARRAY ref while "strict refs"` [download] Any idea why?	[reply] [d/l]
Re^3: Adding an element to an array by davido (Cardinal) on Oct 15, 2015 at 06:59 UTC
Witness the following: $ perl -Mstrict -Mdiagnostics -E 'my $a = "3"; say $a->[0];' Can't use string ("3") as an ARRAY ref while "strict refs" in use at - +e line 1 (#1) (F) You've told Perl to dereference a string, something which use strict blocks to prevent it happening accidentally. See "Symbolic references" in perlref. This can be triggered by an @ o +r $ in a double-quoted string immediately before interpolating a varia +ble, for example in "user @$twitter_id", which says to treat the conten +ts of $twitter_id as an array reference; use a \ to have a literal @ symbol followed by the contents of $twitter_id: "user \@$twitter_i +d". Uncaught exception from user code: Can't use string ("3") as an ARRAY ref while "strict refs" in use +at -e line 1. [download] If you are getting this message, then your code is doing what my code demonstrates. It may take a more complex path to get there, but the result it the same; some variable that you think has an array reference in it actually has the string "`3`", and you are attempting to dereference it. Dave	[reply] [d/l] [select]
Re^3: Adding an element to an array by poj (Abbot) on Oct 14, 2015 at 20:10 UTC
You will need to show the code that gives that error poj	[reply]
Re^4: Adding an element to an array by Anonymous Monk on Oct 15, 2015 at 13:57 UTC
Re^4: Adding an element to an array by sandeepb (Novice) on Oct 16, 2015 at 10:51 UTC