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Re: Re: Variant permutation

by gmax (Abbot)
on Aug 31, 2003 at 09:37 UTC ( #288006=note: print w/replies, xml ) Need Help??

in reply to Re: Variant permutation
in thread Variant permutation

An example would be better than any explanation.

my $headers = { locations => ['USA', 'UK'], departments => ['pers', 'dev','sales'], gender => ['m', 'f'] }; __END__ The ultimate goal will be USA UK + ---------------------------------- --------------------------------- pers dev sales USA pers dev sales UK -------- ------- --------- ------- -------- ------- --------- ------ m f pers m f dev m f sales m f USA m f pers m f dev m f sales m f UK - - --- - - --- - - ----- - - --- - - ---- - - --- - - ----- - - -- a b c d e f g h i j k l m n o p q r s t u v w x

Take this schema, and see why I said that order is important and I take the variation only when the last one is changing.

For every location I list the departments; for each department a breakdown by gender (columns a b d e n o p q s t), followed by a department total (columns c f i o r u). Then there is a breakdown by location (columns g h v w) with its grand total (columns l x).

If I permute 'USA'-'m' before 'USA'-'pers'-'m' I am breaking the schema.

The algorithm I am dealing with is a little more complex than this, since it is taking information about where to find each item, and generating code to retrieve the relevant data from a database.

The permutations are needed to create the appropriate conditions for retrieving each column of data. All the conditions are merged together into a giant SQL statement that will fetch the data according to my instructions (SUM, COUNT, AVG).

More on this subject when I adjust nicely all the above into a module. :)

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