sim.field.grid
Class SparseGrid2D
java.lang.Object
sim.field.SparseField
sim.field.grid.SparseGrid2D
- All Implemented Interfaces:
- Grid2D, java.io.Serializable
- public class SparseGrid2D
- extends SparseField
- implements Grid2D
A storage facility for sparse objects in discrete 2D space, using HashMaps. SparseGrid2D differs from ObjectGrid2D
in several respects:
- SparseGrid2D can store more than one object at a location. ObjectGrid2D cannot.
- ObjectGrid2D can store an object at more than one location (though it's bad form!).
- SparseGrid2D can efficiently (O(1)) tell you the location of an object.
- SparseGrid2D can efficiently (O(#objs)) scan through all objects. The best you can do with ObjectGrid2D is search its array (which might have many empty slots).
- Storing an object, finding its location, or changing its location, in a SparseGrid2D is O(1) but requires several HashMap lookups and/or removes, which has a significant constant overhead.
- SparseGrid2D can associate objects with any 2D integer location. ObjectGrid2D's locations are restricted to be within its array.
Generally speaking, if you have a grid of objects, one per location, you should use an ObjectGrid2D. If you have a large grid occupied by a few objects, or those objects can pile up on the same grid location, you should use a SparseGrid2D.
In either case, you might consider storing the location of an object IN THE OBJECT ITSELF if you need to query for the object location often -- it's faster than the hashtable lookup in SparseGrid2D, and certainly faster than searching the entire array of an ObjectGrid2D.
Boundaries. SparseGrid2D has no boundaries at all. width and height exist only to allow
you to define pseudo-boundaries for toroidal computation; and to provide typical bounds for visualization. But you can
attach any coordinate as a location for an object with no restrictions.
Setting and getting an object and its Location. The method setObjectLocation(...) methods set the location of the object
(to an Int2D or an location).
The method getObjectsAtLocation(Object location), inherited from SparseField, returns a Bag (which you MUST NOT modify)
containing all objects at a given location (which must be provided in the form of an Int2D or MutableInt2D). The numObjectsAtLocation(location)
method returns the number of such objects. The getObjectsAtLocations(Bag locations, Bag putInHere) gathers objects
at a variety of locations and puts them in the bag you provide. The getAllObjects() method returns all objects in a bag you
must NOT modiify. The removeObjectsAtLocation(Object location) method removes and returns all objects at a given location
(defined as an Int2D or MutableDouble2D). The exists method tells you if the object exists in the field.
Neighborhood Lookups. The method getObjectsAtLocationOfObject returns all Objects at the same location as the provided
object (in a Bag, which must NOT modify). The various getNeighbors...Distance(...) methods return all locations defined by certain
distance bounds, or all the objects stored at those locations. They are expensive to compute and it may be wiser to compute them by hand
if there aren't many.
- See Also:
- Serialized Form
Method Summary |
int |
dlx(int x,
int y)
Hex downleft x. |
int |
dly(int x,
int y)
Hex downleft y. |
int |
downx(int x,
int y)
Hex down x. |
int |
downy(int x,
int y)
Hex down y. |
int |
drx(int x,
int y)
Hex downright x. |
int |
dry(int x,
int y)
Hex downright y. |
int |
getHeight()
Returns the height of the grid |
Bag |
getNeighborsHamiltonianDistance(int x,
int y,
int dist,
boolean toroidal,
Bag result,
IntBag xPos,
IntBag yPos)
Gets all neighbors of a location that satisfy abs(x-X) + abs(y-Y) <= dist. |
void |
getNeighborsHamiltonianDistance(int x,
int y,
int dist,
boolean toroidal,
IntBag xPos,
IntBag yPos)
Gets all neighbors of a location that satisfy abs(x-X) + abs(y-Y) <= dist. |
Bag |
getNeighborsHexagonalDistance(int x,
int y,
int dist,
boolean toroidal,
Bag result,
IntBag xPos,
IntBag yPos)
Gets all neighbors located within the hexagon centered at (X,Y) and 2*dist+1 cells from point to opposite point
inclusive. |
void |
getNeighborsHexagonalDistance(int x,
int y,
int dist,
boolean toroidal,
IntBag xPos,
IntBag yPos)
Gets all neighbors located within the hexagon centered at (X,Y) and 2*dist+1 cells from point to opposite point
inclusive. |
Bag |
getNeighborsMaxDistance(int x,
int y,
int dist,
boolean toroidal,
Bag result,
IntBag xPos,
IntBag yPos)
Gets all neighbors of a location that satisfy max( abs(x-X) , abs(y-Y) ) <= dist. |
void |
getNeighborsMaxDistance(int x,
int y,
int dist,
boolean toroidal,
IntBag xPos,
IntBag yPos)
Gets all neighbors of a location that satisfy max( abs(x-X) , abs(y-Y) ) <= dist. |
Int2D |
getObjectLocation(java.lang.Object obj)
Returns the object location, or null if there is no such object. |
Double2D |
getObjectLocationAsDouble2D(java.lang.Object obj)
Returns the object location as a Double2D, or as null if there is no such object. |
Bag |
getObjectsAtLocation(int x,
int y)
Returns a bag containing all the objects at a given location, or null when there are no objects at the location. |
Bag |
getObjectsAtLocations(IntBag xPos,
IntBag yPos,
Bag result)
For each location, puts all such objects into the result bag. |
int |
getWidth()
Returns the width of the grid |
int |
numObjectsAtLocation(int x,
int y)
Returns the number of objects stored in the grid at the given location. |
Bag |
removeObjectsAtLocation(int x,
int y)
Removes all the objects stored at the given location and returns them as a Bag (which you are free to modify). |
boolean |
setObjectLocation(java.lang.Object obj,
Int2D location)
Changes the location of an object, or adds if it doesn't exist yet. |
boolean |
setObjectLocation(java.lang.Object obj,
int x,
int y)
Changes the location of an object, or adds if it doesn't exist yet. |
int |
stx(int x)
Simple [and fast] toroidal x. |
int |
sty(int y)
Simple [and fast] toroidal y. |
boolean |
trb(int x,
int y)
Horizontal edge is on the bottom for triangle. |
boolean |
trt(int x,
int y)
Horizontal edge is on the top for triangle. |
int |
tx(int x)
Toroidal x. |
int |
ty(int y)
Toroidal y. |
int |
ulx(int x,
int y)
Hex upleft x. |
int |
uly(int x,
int y)
Hex upleft y. |
int |
upx(int x,
int y)
Hex up x. |
int |
upy(int x,
int y)
Hex up y. |
int |
urx(int x,
int y)
Hex upright x. |
int |
ury(int x,
int y)
Hex upright y. |
Methods inherited from class sim.field.SparseField |
clear, exists, getAllObjects, getObjectIndex, getObjectsAtLocation, getObjectsAtLocationOfObject, getObjectsAtLocations, getRawObjectLocation, iterator, locationBagIterator, numObjectsAtLocation, numObjectsAtLocationOfObject, remove, removeObjectsAtLocation, setObjectLocation |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
width
protected int width
height
protected int height
SparseGrid2D
public SparseGrid2D(int width,
int height)
getWidth
public int getWidth()
- Returns the width of the grid
- Specified by:
getWidth
in interface Grid2D
getHeight
public int getHeight()
- Returns the height of the grid
- Specified by:
getHeight
in interface Grid2D
tx
public final int tx(int x)
- Description copied from interface:
Grid2D
- Toroidal x. The following definition:
final int length = this.length;
if (z >= 0) return (z % length);
final int length2 = (z % length) + length;
if (length2 < length) return length2;
return 0;
... produces the correct code and is 27 bytes, so it's likely to be inlined in Hotspot for 1.4.1.
- Specified by:
tx
in interface Grid2D
ty
public final int ty(int y)
- Description copied from interface:
Grid2D
- Toroidal y. The following definition:
final int length = this.length;
if (z >= 0) return (z % length);
final int length2 = (z % length) + length;
if (length2 < length) return length2;
return 0;
... produces the correct code and is 27 bytes, so it's likely to be inlined in Hotspot for 1.4.1.
- Specified by:
ty
in interface Grid2D
stx
public int stx(int x)
- Description copied from interface:
Grid2D
- Simple [and fast] toroidal x. Use this if the values you'd pass in never stray
beyond (-width ... width * 2) not inclusive. It's a bit faster than the full
toroidal computation as it uses if statements rather than two modulos.
The following definition:
{ int width = this.width; if (x >= 0) { if (x < width) return x; return x - width; } return x + width; }
...produces the shortest code (24 bytes) and is inlined in Hotspot for 1.4.1. However
in most cases removing the int width = this.width; is likely to be a little faster if most
objects are usually within the toroidal region.
- Specified by:
stx
in interface Grid2D
sty
public int sty(int y)
- Description copied from interface:
Grid2D
- Simple [and fast] toroidal y. Use this if the values you'd pass in never stray
beyond (-height ... height * 2) not inclusive. It's a bit faster than the full
toroidal computation as it uses if statements rather than two modulos.
The following definition:
{ int height = this.height; if (y >= 0) { if (y < height) return y ; return y - height; } return y + height; }
...produces the shortest code (24 bytes) and is inlined in Hotspot for 1.4.1. However
in most cases removing the int height = this.height; is likely to be a little faster if most
objects are usually within the toroidal region.
- Specified by:
sty
in interface Grid2D
ulx
public int ulx(int x,
int y)
- Description copied from interface:
Grid2D
- Hex upleft x.
- Specified by:
ulx
in interface Grid2D
uly
public int uly(int x,
int y)
- Description copied from interface:
Grid2D
- Hex upleft y.
- Specified by:
uly
in interface Grid2D
urx
public int urx(int x,
int y)
- Description copied from interface:
Grid2D
- Hex upright x.
- Specified by:
urx
in interface Grid2D
ury
public int ury(int x,
int y)
- Description copied from interface:
Grid2D
- Hex upright y.
- Specified by:
ury
in interface Grid2D
dlx
public int dlx(int x,
int y)
- Description copied from interface:
Grid2D
- Hex downleft x.
- Specified by:
dlx
in interface Grid2D
dly
public int dly(int x,
int y)
- Description copied from interface:
Grid2D
- Hex downleft y.
- Specified by:
dly
in interface Grid2D
drx
public int drx(int x,
int y)
- Description copied from interface:
Grid2D
- Hex downright x.
- Specified by:
drx
in interface Grid2D
dry
public int dry(int x,
int y)
- Description copied from interface:
Grid2D
- Hex downright y.
- Specified by:
dry
in interface Grid2D
upx
public int upx(int x,
int y)
- Description copied from interface:
Grid2D
- Hex up x.
- Specified by:
upx
in interface Grid2D
upy
public int upy(int x,
int y)
- Description copied from interface:
Grid2D
- Hex up y.
- Specified by:
upy
in interface Grid2D
downx
public int downx(int x,
int y)
- Description copied from interface:
Grid2D
- Hex down x.
- Specified by:
downx
in interface Grid2D
downy
public int downy(int x,
int y)
- Description copied from interface:
Grid2D
- Hex down y.
- Specified by:
downy
in interface Grid2D
trb
public boolean trb(int x,
int y)
- Description copied from interface:
Grid2D
- Horizontal edge is on the bottom for triangle. True if x + y is odd.
One definition of this is return ((x + y) & 1) == 1;
- Specified by:
trb
in interface Grid2D
trt
public boolean trt(int x,
int y)
- Description copied from interface:
Grid2D
- Horizontal edge is on the top for triangle. True if x + y is even.
One definition of this is return ((x + y) & 1) == 0;
- Specified by:
trt
in interface Grid2D
numObjectsAtLocation
public int numObjectsAtLocation(int x,
int y)
- Returns the number of objects stored in the grid at the given location.
getObjectsAtLocation
public Bag getObjectsAtLocation(int x,
int y)
- Returns a bag containing all the objects at a given location, or null when there are no objects at the location.
You should NOT MODIFY THIS BAG. This is the actual container bag, and modifying it will almost certainly break
the Sparse Field object. If you want to modify the bag, make a copy and modify the copy instead,
using something along the lines of new Bag(foo.getObjectsAtLocation(location)) .
Furthermore, changing values in the Sparse Field may result in a different bag being used -- so you should
not rely on this bag staying valid.
getObjectLocationAsDouble2D
public Double2D getObjectLocationAsDouble2D(java.lang.Object obj)
- Returns the object location as a Double2D, or as null if there is no such object.
getObjectLocation
public Int2D getObjectLocation(java.lang.Object obj)
- Returns the object location, or null if there is no such object.
removeObjectsAtLocation
public Bag removeObjectsAtLocation(int x,
int y)
- Removes all the objects stored at the given location and returns them as a Bag (which you are free to modify).
setObjectLocation
public boolean setObjectLocation(java.lang.Object obj,
int x,
int y)
- Changes the location of an object, or adds if it doesn't exist yet. Returns false
if the object is null (null objects cannot be put into the grid).
setObjectLocation
public boolean setObjectLocation(java.lang.Object obj,
Int2D location)
- Changes the location of an object, or adds if it doesn't exist yet. Returns false
if the object is null (null objects cannot be put into the grid) or if the location is null.
getNeighborsMaxDistance
public void getNeighborsMaxDistance(int x,
int y,
int dist,
boolean toroidal,
IntBag xPos,
IntBag yPos)
- Description copied from interface:
Grid2D
- Gets all neighbors of a location that satisfy max( abs(x-X) , abs(y-Y) ) <= dist. This region forms a
square 2*dist+1 cells across, centered at (X,Y). If dist==1, this
is equivalent to the so-called "Moore Neighborhood" (the eight neighbors surrounding (X,Y)), plus (X,Y) itself.
Places each x and y value of these locations in the provided IntBags xPos and yPos, clearing the bags first.
- Specified by:
getNeighborsMaxDistance
in interface Grid2D
getNeighborsHamiltonianDistance
public void getNeighborsHamiltonianDistance(int x,
int y,
int dist,
boolean toroidal,
IntBag xPos,
IntBag yPos)
- Description copied from interface:
Grid2D
- Gets all neighbors of a location that satisfy abs(x-X) + abs(y-Y) <= dist. This region forms a diamond
2*dist+1 cells from point to opposite point inclusive, centered at (X,Y). If dist==1 this is
equivalent to the so-called "Von-Neumann Neighborhood" (the four neighbors above, below, left, and right of (X,Y)),
plus (X,Y) itself.
Places each x and y value of these locations in the provided IntBags xPos and yPos, clearing the bags first.
- Specified by:
getNeighborsHamiltonianDistance
in interface Grid2D
getNeighborsHexagonalDistance
public void getNeighborsHexagonalDistance(int x,
int y,
int dist,
boolean toroidal,
IntBag xPos,
IntBag yPos)
- Description copied from interface:
Grid2D
- Gets all neighbors located within the hexagon centered at (X,Y) and 2*dist+1 cells from point to opposite point
inclusive.
If dist==1, this is equivalent to the six neighbors immediately surrounding (X,Y),
plus (X,Y) itself.
Places each x and y value of these locations in the provided IntBags xPos and yPos, clearing the bags first.
- Specified by:
getNeighborsHexagonalDistance
in interface Grid2D
getNeighborsMaxDistance
public Bag getNeighborsMaxDistance(int x,
int y,
int dist,
boolean toroidal,
Bag result,
IntBag xPos,
IntBag yPos)
- Gets all neighbors of a location that satisfy max( abs(x-X) , abs(y-Y) ) <= dist. This region forms a
square 2*dist+1 cells across, centered at (X,Y). If dist==1, this
is equivalent to the so-called "Moore Neighborhood" (the eight neighbors surrounding (X,Y)), plus (X,Y) itself.
Places each x and y value of these locations in the provided IntBags xPos and yPos, clearing the bags first.
Then places into the result Bag the objects at each of those locations clearning it first.
Returns the result Bag.
null may be passed in for the various bags, though it is more efficient to pass in a 'scratch bag' for
each one.
getNeighborsHamiltonianDistance
public Bag getNeighborsHamiltonianDistance(int x,
int y,
int dist,
boolean toroidal,
Bag result,
IntBag xPos,
IntBag yPos)
- Gets all neighbors of a location that satisfy abs(x-X) + abs(y-Y) <= dist. This region forms a diamond
2*dist+1 cells from point to opposite point inclusive, centered at (X,Y). If dist==1 this is
equivalent to the so-called "Von-Neumann Neighborhood" (the four neighbors above, below, left, and right of (X,Y)),
plus (X,Y) itself.
Places each x and y value of these locations in the provided IntBags xPos and yPos, clearing the bags first.
Then places into the result Bag the objects at each of those locations, clearning it first.
Returns the result Bag (constructing one if null had been passed in).
null may be passed in for the various bags, though it is more efficient to pass in a 'scratch bag' for
each one.
getNeighborsHexagonalDistance
public Bag getNeighborsHexagonalDistance(int x,
int y,
int dist,
boolean toroidal,
Bag result,
IntBag xPos,
IntBag yPos)
- Gets all neighbors located within the hexagon centered at (X,Y) and 2*dist+1 cells from point to opposite point
inclusive.
If dist==1, this is equivalent to the six neighbors immediately surrounding (X,Y),
plus (X,Y) itself.
Places each x and y value of these locations in the provided IntBags xPos and yPos, clearing the bags first.
Then places into the result Bag the objects at each of those locations clearning it first.
Returns the result Bag (constructing one if null had been passed in).
null may be passed in for the various bags, though it is more efficient to pass in a 'scratch bag' for
each one.
getObjectsAtLocations
public Bag getObjectsAtLocations(IntBag xPos,
IntBag yPos,
Bag result)
- For each location, puts all such objects into the result bag. Returns the result bag.
If the provided result bag is null, one will be created and returned.