(jeffa) Re: Sorting data pullled in by DBI

Everybody has told you how to sort (college, then id), but nobody told you to USE STRICT!!! ;)

Now, some handy short-cuts in Perl programming:

Instead of using the ternery operator twice on each column for each row, you could just handle empty columns in the first check:

$student_name = (defined $row[1]) ? $row[1] : '&nbsp;';
$student_blah = .... ad naseum
[download]

Or you could avoid all that extra typing by utilizing map:

while (my @row = $sth_report->fetchrow_array) {
   @row = map { $_ || '&nbsp;' } @row;

   # .... rest of code
}
[download]

Also,the only variable you need is one to store the college (actually, you don't even need that one either! :D) ... the rest can be kept in @row, which can be then stored in a hash whose keys are the colleges, and whose values are the rows of the students (ordered by id) who belong to that college:

my %college;
while (my @row = $sth_report->fetchrow_array) {
   @row = map { $_ || '&nbsp;' } @row;
   my $college = pop @row;
  
   push $college{$college}, [@row];
}
[download]

And some code to print it back out:

foreach my $college (keys %college) {
    print "$college:\n";
    foreach my $row (@{$college{$college}}) {
        print "\t", join(', ', @$row),"\n";
    }
}
[download]

Hope this helps. :)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

Comment on (jeffa) Re: Sorting data pullled in by DBI Select or Download Code

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Re2: Sorting data pullled in by DBI by blakem (Monsignor) on Mar 18, 2002 at 01:41 UTC
My favorite idiom for defaulting a set of values is: `# psuedocode $_ = DEFAULT for grep !CONDITION, @VALUES; # as it applies in this situation $_ = ' ' for grep !$_, @row;` [download] -Blake	[reply] [d/l]
Re: Re2: Sorting data pullled in by DBI by Kanji (Parson) on Mar 18, 2002 at 02:57 UTC
The problem with `!$_` (and jeffa's `map` example), is that it tests for truth, so you also end up substituting any values that match `0` instead of only those that are `undef`. Perhaps you meant to use `!defined` instead? --k.	[reply]
Re4: Sorting data pullled in by DBI by blakem (Monsignor) on Mar 18, 2002 at 03:46 UTC
Yes, `!defined` is probably a better CONDITON for the original data... I was merely refactoring the given map code. However, since you probably want the empty string to be defaulted as well, I'd probably use something like: `$_ = ' ' for grep {!defined or $_ eq ''} @arr;` [download] -Blake	[reply] [d/l] [select]