Hello Andrew,
>> I would appreciate if a function to sort sets could be provided in GMPL.
I have implemented the possibility to sort sets in GLPK.
== Syntax ==
The syntax I have chosen is to add a keyword "sorted" to domains:
set B, dimen 2 := setof{sorted (i,j) in A} (i,j);
This syntax allows to sort by any sorting criteria like:
set C := setof{(k,l) in A} (k-l, k);
set D := setof{sorted (i,j) in C}j;
This example creates a set D containing the elements of the first column of
A sorted by the difference of the columns.
== Implementation Details ==
These are the changes:
In glpalv.h I have added a definition of avl_find_next_node() and changed
glpalv.c accordingly.
In glpmpl.h I have added a new token T_SORTED. I added a field sorted to
struct ARRAY.
In glpmpl.c I have added T_SORTED to the reserved keywords. The token is
used in indexing_expression() to set a flag sorted in struct ARRAY.
In glpmpl03.c I have added a new function sort_elemset() which first assures
that the AVL tree is build and then uses the tree to relink the MEMBERSs of
the set.
== Patches ==
Please, find the patches here:
old revision 377 - new revision 379
http://glpk.dyndns.org/viewvc/svn/glpk/glpk/branches/glpk-4.34-dot/include/glpavl.h?view=diff&r1=379&r2=377&diff_format=h
http://glpk.dyndns.org/viewvc/svn/glpk/glpk/branches/glpk-4.34-dot/include/glpmpl.h?view=diff&r1=379&r2=377&diff_format=h
http://glpk.dyndns.org/viewvc/svn/glpk/glpk/branches/glpk-4.34-dot/src/glpmpl03.c?view=diff&r1=379&r2=377&diff_format=h
http://glpk.dyndns.org/viewvc/svn/glpk/glpk/branches/glpk-4.34-dot/src/glpmpl01.c?view=diff&r1=379&r2=377&diff_format=h
http://glpk.dyndns.org/viewvc/svn/glpk/glpk/branches/glpk-4.34-dot/src/glpavl.c?view=diff&r1=379&r2=377&diff_format=h
Here you can also download the full files.
Best regards
Xypron
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