Solved

Sorting

Posted on 1998-09-10
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Last Modified: 2010-03-05
I want to sort an array of arrays.

I use the line

sort byName @records;

where byName is defined as

sub byName{
      return $records[$a]->[$SITENAME] cmp $records[$b]->[$SITENAME];
}

Please explain why this doesn't work.
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Comment
Question by:rafistern
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11 Comments
 

Expert Comment

by:arhnold
ID: 1204798
Just to clarify:  Do you want each subarray sorted within itself or are you trying to do some sort of sorting between the subarrays?
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Expert Comment

by:ozo
ID: 1204799
try
  @records[ sort byName (0..$#records)];
or
  sort {$a->[$SITENAME] cmp $b->[$SITENAME]} @records;
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Author Comment

by:rafistern
ID: 1204800
arnhold,
I have a set of arrays which contain dat that I read from a flat file database. I want to sort the arrays so that they will be in ascending order sorted by a key field (the name of the item to which all the data in the record refers).

ozo,
I will try your suggestions.

Thanks,
Rafi
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Author Comment

by:rafistern
ID: 1204801
ozo,
It doesn't work. Anyone know what the correct syntax is for this operation? I could always write my own sorting routine.. but it's a shame not to use the existing function "sort".
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Expert Comment

by:ozo
ID: 1204802
What doesn't work.
How is @records defined?
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Author Comment

by:rafistern
ID: 1204803
I just found the answer myself.
@records= was missing at the beginning of the line!
What a stupid mistake!!

Thanks, guys.
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Author Comment

by:rafistern
ID: 1204804
P.S.
ozo, I will give you points for your answer because your syntax was correct although you didn't find my other mistake. Post me a blank answer.
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Accepted Solution

by:
ozo earned 50 total points
ID: 1204805

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Expert Comment

by:ozo
ID: 1204806
> you didn't find my other mistake
How could I, when you didn't tell me you wanted to replace @records with the sorted array?
That's why I asked what wasn't working.
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Author Comment

by:rafistern
ID: 1204807
It's not really worth arguing about but the line which I posted:

sort byName @records;

has got to be just one of the most useless lines of code as it doesn't return anything. Thanks for the correct syntax for the sorting function. It's now working fantastically.
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Expert Comment

by:ozo
ID: 1204808
If that's the complete statement, yes, and perl -w will even warn you about that.
But besides assigning it to @records, you might have wanted to return it from a sub, or assign it to something else, or print it, or map it, or foreach over it, or pass it to another function...
Anyway, I'm glad it's working for you now.
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