factor/extra/path-finding/path-finding-tests.factor

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Factor

! Copyright (C) 2010 Samuel Tardieu.
! See http://factorcode.org/license.txt for BSD license.
USING: arrays assocs combinators hashtables kernel literals math math.functions
math.vectors memoize path-finding sequences sorting splitting strings tools.test ;
IN: path-finding.tests
! Use a 10x9 maze (see below) to try to go from s to e, f or g.
! X means that a position is unreachable.
! The costs model is:
! - going up costs 5 points
! - going down costs 1 point
! - going left or right costs 2 points
<<
TUPLE: maze < astar ;
: reachable? ( pos -- ? )
first2 [ 2 * 5 + ] [ 2 + ] bi* $[
" 0 1 2 3 4 5 6 7 8 9
0 X X X X X X X X X X
1 X s f X X
2 X X X X X X X X X
3 X X X X X X X X X
4 X X X X X X
5 X X X X X
6 X X X X X X e X
7 X g X X
8 X X X X X X X X X X"
"\n" split ] nth nth CHAR: X = not ;
M: maze neighbours
drop
first2
{ [ 1 + 2array ] [ 1 - 2array ] [ [ 1 + ] dip 2array ] [ [ 1 - ] dip 2array ] } 2cleave
4array
[ reachable? ] filter ;
M: maze heuristic
drop v- [ abs ] [ + ] map-reduce ;
M: maze cost
drop 2dup [ first ] same? [ [ second ] bi@ > 1 5 ? ] [ 2drop 2 ] if ;
: test1 ( to -- path considered )
{ 1 1 } swap maze new [ find-path ] [ considered ] bi ;
>>
! Existing path from s to f
{
{
{ 1 1 }
{ 2 1 }
{ 3 1 }
{ 4 1 }
{ 4 2 }
{ 4 3 }
{ 4 4 }
{ 4 5 }
{ 4 6 }
{ 4 7 }
{ 5 7 }
{ 6 7 }
{ 7 7 }
{ 8 7 }
{ 8 6 }
}
} [
{ 8 6 } test1 drop
] unit-test
! Check that only the right positions have been considered in the s to f path
{ 7 } [ { 7 1 } test1 nip length ] unit-test
! Non-existing path from s to g -- all positions must have been considered
{ f 26 } [ { 1 7 } test1 length ] unit-test
! Look for a path between A and C. The best path is A --> D --> C. C will be placed
! in the open set early because B will be examined first. This checks that the evaluation
! of C is correctly replaced in the open set.
!
! We use no heuristic here and always return 0.
!
! (5)
! B ---> C <--------
! \ (2)
! ^ ^ |
! | | |
! (1) | | (2) |
! | | |
!
! A ---> D ---------> E ---> F
! (2) (1) (1)
<<
! In this version, we will use the quotations-aware version through <astar>.
MEMO: routes ( -- hash ) $[ { "ABD" "BC" "C" "DCE" "ECF" } [ unclip swap 2array ] map >hashtable ] ;
: n ( pos -- neighbours )
routes at ;
: c ( from to -- cost )
"" 2sequence H{ { "AB" 1 } { "AD" 2 } { "BC" 5 } { "DC" 2 } { "DE" 1 } { "EC" 2 } { "EF" 1 } } at ;
: test2 ( fromto -- path considered )
first2 [ n ] [ c ] [ 2drop 0 ] <astar> [ find-path ] [ considered natural-sort >string ] bi ;
>>
! Check path from A to C -- all nodes but F must have been examined
{ "ADC" "ABCDE" } [ "AC" test2 [ >string ] dip ] unit-test
! No path from D to B -- all nodes reachable from D must have been examined
{ f "CDEF" } [ "DB" test2 ] unit-test
! Find a path using BFS. There are no path from F to A, and the path from D to
! C does not include any other node.
{ f } [ "FA" first2 routes <bfs> find-path ] unit-test
{ "DC" } [ "DC" first2 routes <bfs> find-path >string ] unit-test
<<
! Build the costs as expected by the dijkstra word.
MEMO: costs ( -- costs )
routes keys [ dup dup n [ dup [ c ] dip swap 2array ] with { } map-as >hashtable 2array ] map >hashtable ;
: test3 ( fromto -- path considered )
first2 costs <dijkstra> [ find-path ] [ considered natural-sort >string ] bi ;
>>
! Check path from A to C -- all nodes but F must have been examined
{ "ADC" "ABCDE" } [ "AC" test3 [ >string ] dip ] unit-test
! No path from D to B -- all nodes reachable from D must have been examined
{ f "CDEF" } [ "DB" test3 ] unit-test
{ { 1 3 } } [
1 3 H{
{ 1 H{ { 2 0 } { 3 0 } } }
{ 2 H{ { 3 0 } { 1 0 } { 4 0 } } }
{ 3 H{ { 4 0 } } }
{ 4 H{ } }
} <dijkstra> find-path
] unit-test