MapsThe data type map can be used to store objects of an arbitrary type I together with an associated key of type pointer, item, or int.Remark: Maps are implemented by hashing with chaining. You can think of them as a variant of Dictionary Arrays optimized for keys of type pointer, item, or int. ExampleThe following program generates a list of segments (type item) and associates a random bit (color) with each segment using a map. Then it outputs each segment and its color.
#include <LEDA/geo/segment.h>
#include <LEDA/core/map.h>
#include <LEDA/core/list.h>
using namespace leda;
int main()
{
list<segment> seglist;
int i;
for (i=0;i<10;i++) {
segment s(0,i,2*i,3*i);
seglist.append(s);
}
map<segment,int> color;
segment s;
forall(s,seglist) color[s]=rand_int(0,1);
forall(s,seglist) std::cout << s << " " << color[s] << std::endl;
return 0;
}
Strengths
Disadvantages
TipsIf you want to store objects with an associated key of type pointer, item, or int use map, otherwise consider using one of the related data types. |
See also:Data types with key of linearly ordered type: Data types with key of hashed type: Hashing Arrays. Manual Entries: |