• Bill Baxter <dnewsgroup billbaxter.com> Mar 06 2008
• BCS <ao pathlink.com> Mar 06 2008
• Bill Baxter <dnewsgroup billbaxter.com> Mar 06 2008
• Jascha Wetzel <firstname mainia.de> Mar 07 2008

Bill Baxter <dnewsgroup billbaxter.com> writes:

Anyone have a sort routine that can operate simultaneously on multiple 
arrays of data?

It's basically a lexical sort kind of thing, but all the keys and values 
are in different arrays:
int[] key1;
int[] key2;
ValueT1[] values;
ValueT2[] other_values;

Datum i is made up of (key1[i],key2[i],values[i],other_values[i]).

But they're all stored in separate arrays rather than interleaved in a 
struct.

The goal is to avoid copying the whole mess to an interleaved array in 
order to sort it, and then copying it back to separate arrays.

--bb

BCS <ao pathlink.com> writes:

Reply to Bill,

 Anyone have a sort routine that can operate simultaneously on multiple
 arrays of data?
 
 It's basically a lexical sort kind of thing, but all the keys and
 values
 are in different arrays:
 int[] key1;
 int[] key2;
 ValueT1[] values;
 ValueT2[] other_values;
 Datum i is made up of (key1[i],key2[i],values[i],other_values[i]).
 
 But they're all stored in separate arrays rather than interleaved in a
 struct.
 
 The goal is to avoid copying the whole mess to an interleaved array in
 order to sort it, and then copying it back to separate arrays.
 
 --bb
 


I don't known of one but... This is ugly... make struct that has just a pointer 
to the key and an int. set the opCmp to chain to the key and then fill an 
array with them referencing the keys. Then fill the ints with 0 to whatever. 
When the thing is sorted you have the index map. from there you can get fancy 
and do an in place reorder (double yuck) or copy each array and move the 
items back into the correct cells (or if you don't care, do the reorder on 
the way out and swap in the new array for the old).

How this will compare to a real multi-array sort will depend on a lot of 
things.

Bill Baxter <dnewsgroup billbaxter.com> writes:

BCS wrote:
 Reply to Bill,
 
 Anyone have a sort routine that can operate simultaneously on multiple
 arrays of data?

 It's basically a lexical sort kind of thing, but all the keys and
 values
 are in different arrays:
 int[] key1;
 int[] key2;
 ValueT1[] values;
 ValueT2[] other_values;
 Datum i is made up of (key1[i],key2[i],values[i],other_values[i]).

 But they're all stored in separate arrays rather than interleaved in a
 struct.

 The goal is to avoid copying the whole mess to an interleaved array in
 order to sort it, and then copying it back to separate arrays.

 --bb


 I don't known of one but... This is ugly... make struct that has just a 
 pointer to the key and an int. set the opCmp to chain to the key and 
 then fill an array with them referencing the keys. Then fill the ints 
 with 0 to whatever. When the thing is sorted you have the index map. 
 from there you can get fancy and do an in place reorder (double yuck) or 
 copy each array and move the items back into the correct cells (or if 
 you don't care, do the reorder on the way out and swap in the new array 
 for the old).
 
 How this will compare to a real multi-array sort will depend on a lot of 
 things.


Hmm.  Oh well.  I don't really want to have to allocate a whole separate 
dummy array for indices, but that does seem to be the only way with 
typcial sort routines.

I just went the brute-force way of modifying Oskar's sort routine to 
handle the case I need.

--bb

Jascha Wetzel <firstname mainia.de> writes:

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Bill Baxter wrote:
 Anyone have a sort routine that can operate simultaneously on multiple 
 arrays of data?
 
 It's basically a lexical sort kind of thing, but all the keys and values 
 are in different arrays:
 int[] key1;
 int[] key2;
 ValueT1[] values;
 ValueT2[] other_values;
 
 Datum i is made up of (key1[i],key2[i],values[i],other_values[i]).
 
 But they're all stored in separate arrays rather than interleaved in a 
 struct.
 
 The goal is to avoid copying the whole mess to an interleaved array in 
 order to sort it, and then copying it back to separate arrays.
 
 --bb


i thought that should be easy with tuple parameters, but something that 
i think is a bug stopped my litte test. see the attachment.
in line 11 the type of b is char[][] (as expected), but using it as such 
gives an error. bummer...