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[求助] 在看例子时有几个问题看不懂

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发表于 2012-6-20 08:59:43 | 显示全部楼层 |阅读模式
新手,在看netlogo自带的例子时,有几行程序看不懂,希望高手能够指点。1 P+ h- ^% ~* j7 q
netlogo自带的social science--traffic grid这一例子当中,0 C- [) K' O: d$ p4 X7 H0 C
globals+ y* P. ~5 q+ H& H% q
[1 _& o  J" p% }9 d
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* T( U* M2 d' ?7 y; ~$ b1 ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) f* f$ T' r! Q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 K; ]3 o- x$ J3 t% o' z. ]1 C& Z
                           ;; it is to accelerate or decelerate7 E" c+ @4 p( p$ {
  phase                    ;; keeps track of the phase" J; q6 m! c4 S; ~) @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ s! e' p- Y& G  M3 l- d6 }  current-light            ;; the currently selected light
9 t+ {! B, |5 M
9 M0 m# w1 T9 i7 O  ;; patch agentsets) }; B( B) C, \" X# _, Y3 b/ q
  intersections ;; agentset containing the patches that are intersections% `3 \- w3 U# s/ I" m* H+ ]
  roads         ;; agentset containing the patches that are roads. z) X0 t1 x! ~* s, w- f' t# \
]
) s! H. V6 v" I: e! x  `
& I/ f7 J: P% a/ d* G) m  Vturtles-own
) O, _) w3 R- z1 _) s. R  `3 F4 P[- ~2 [' p5 Q: ]% q( w* l. U
  speed     ;; the speed of the turtle8 R4 f. G8 \  W. A2 g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; h$ B. m* `  x5 M0 ~& {  wait-time ;; the amount of time since the last time a turtle has moved& d7 E/ [0 O1 `6 T- r  s/ P
]
! W5 y4 `; s7 B
4 A; n( @% V! b7 ppatches-own) \2 R6 }( d3 v% \8 Q1 V1 {) t( F
[
. d+ k4 ]$ o5 ]& |* j2 r  intersection?   ;; true if the patch is at the intersection of two roads+ \: A8 j5 Y0 z$ t3 Y5 s( |9 T0 U
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. B9 Q* g4 k: }' V% i
                  ;; false for a non-intersection patches.. e6 n* E" k* |" L7 ]
  my-row          ;; the row of the intersection counting from the upper left corner of the
* y* H$ [6 n4 l8 D* ?; D2 Z                  ;; world.  -1 for non-intersection patches.* o9 ^: n4 X; g$ `
  my-column       ;; the column of the intersection counting from the upper left corner of the
% ~4 T  O) n" X0 v0 C8 j2 O8 y                  ;; world.  -1 for non-intersection patches.
2 Z- [! Y. L; d2 w8 j+ A1 s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% r8 t$ `  z( w2 \  g# \5 G
  auto?           ;; whether or not this intersection will switch automatically.( }0 V2 b. Q0 X7 u1 ~: q# Q' A
                  ;; false for non-intersection patches.
5 W* h; V# \" s$ }. i]8 ~8 e9 p1 q+ V6 u
+ L/ Q# c' q% e$ C7 C2 E
! ]" ]' u4 S, m% [
;;;;;;;;;;;;;;;;;;;;;;
) u$ U2 K  ^2 f/ X6 R;; Setup Procedures ;;
& V: G% u3 f, b" t' S3 z;;;;;;;;;;;;;;;;;;;;;;. s" u: ~; |' m/ }% k; @1 O
$ T2 j, |& x5 A6 B, ^
;; Initialize the display by giving the global and patch variables initial values.
- }  H9 Q+ F( M" R/ t: [" \4 O5 t;; Create num-cars of turtles if there are enough road patches for one turtle to5 V( u4 Z, z& ?  Q: t( O4 i
;; be created per road patch. Set up the plots.4 v( M. V) w2 D+ Q
to setup
* U' S2 p; |7 o  R( Z, b) S  ca/ T. [8 [  R, q9 w1 M
  setup-globals* l' Q- F  H) o1 S

' o/ _1 ~  _6 J/ _0 S' K  ;; First we ask the patches to draw themselves and set up a few variables
) S8 R2 T* D4 O% ]' I$ b" z' M  setup-patches/ a7 E. z$ g, `7 q* U" |
  make-current one-of intersections1 I: G3 T& Q! o; V
  label-current
8 c- ]7 `* J. U, E" V: ~
4 k- j( C9 ~% q4 @# g1 b  set-default-shape turtles "car"5 E: o: \5 F. j  L/ G0 s+ j9 }6 b

0 f$ h! H: M) }- G! ?! u1 \  if (num-cars > count roads)
5 Q" G/ o) w  O) O. A: Y2 ]2 ^  [
* c- Y1 r8 H. l9 d    user-message (word "There are too many cars for the amount of "9 i$ N) z) i: `" F  N* _
                       "road.  Either increase the amount of roads "
; ~+ {$ h' b9 h/ b0 j( Q, n                       "by increasing the GRID-SIZE-X or "" Z+ B4 t9 G, N- d' y0 @- @
                       "GRID-SIZE-Y sliders, or decrease the "
1 q; A7 L+ E- D" ?; T                       "number of cars by lowering the NUMBER slider.\n"
/ F- Z6 h  L/ C" ]                       "The setup has stopped.")
9 k! e) h$ `8 n( U    stop
9 `( e# `/ t/ Y' t  a: u+ l( O  ]
# C5 C: O( {0 g  Y1 I- A+ x$ p- K. w8 l$ Y3 l
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& S4 |. U- ]) ]% u! L
  crt num-cars
) i; k, E* U  E' r/ L) b  [& c+ Z. O* b9 s. A% T8 ]$ c
    setup-cars7 I5 g' O; R3 Q. `) \9 t: U) u+ [
    set-car-color
/ q! W& m3 u  z% I$ K# K7 v    record-data9 ^+ @+ m+ D$ Q* E9 |
  ]
& [0 g5 q* g) \) @2 R
- v% E  k4 T; n  ;; give the turtles an initial speed
; c- V* D2 J! Q# z9 J- f  ask turtles [ set-car-speed ]
0 F. {9 m: g0 |7 h/ L& b# K/ y4 S  n$ y3 c6 B
  reset-ticks9 b: f$ l5 k  n/ V$ U8 K6 v8 s  G8 {
end
* g! Z7 n9 z$ B3 z( B1 I( h6 j$ I
9 \4 P* }0 {7 A/ g+ Y. s# a+ r;; Initialize the global variables to appropriate values4 u, n$ n& G1 v
to setup-globals( j. x! j- j3 Q5 S3 z4 J
  set current-light nobody ;; just for now, since there are no lights yet, Y) M2 n7 O% x) }$ e
  set phase 0* X4 v% q4 T. V* E/ d
  set num-cars-stopped 0
+ k# W4 _+ _% k+ n  w2 y2 O  set grid-x-inc world-width / grid-size-x
, q/ E' c) U: v7 M& m+ `  set grid-y-inc world-height / grid-size-y
5 h/ x0 u2 g. G
% D2 j3 e3 I0 b% R6 A& ^  E' K* P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) b6 Y) ?( o# Y4 }' z
  set acceleration 0.099$ r9 |) I* r; j4 g/ M
end7 s  |" V8 ]( y" E4 \1 w
, Z8 ^$ ]3 e9 U& `
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 L. T1 h, p2 o0 F;; and initialize the traffic lights to one setting
3 ]5 u! O# \: q& ^3 Xto setup-patches# i2 g+ v" y4 B
  ;; initialize the patch-owned variables and color the patches to a base-color
4 G! I& Z+ Q) ?/ L" k- V  ask patches
/ k. X9 S' U2 H/ Y6 S, i  [
# E+ k+ g$ I2 B* W    set intersection? false: q. C, d: E1 R- F
    set auto? false. M7 R" Z- {8 f2 Z% d
    set green-light-up? true
/ I6 m8 w. M; u: v0 m    set my-row -17 K6 A8 F4 R; \7 D  _! {
    set my-column -1! |+ Y% ]+ Q8 ]7 ~% g1 _
    set my-phase -1
+ t; s% Y% n. `6 [  L* E    set pcolor brown + 3
& Z' d$ S5 e( E2 S- Q" V) A3 {  ]! x, ?* Z# w0 F  R, l
8 x; {* ^) }, m4 H
  ;; initialize the global variables that hold patch agentsets! i' o, Z/ A) u, P  L% Y
  set roads patches with0 C# f* I3 N) M# c6 j6 A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 V! S4 i& m- c, r1 W# G2 y& J) H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ ?7 Q1 d* M7 z( w! M& |! i  set intersections roads with
; ]  l% j! J9 x) k0 D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and; A* e: I% B, x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 H7 i0 [, b9 D0 R) f! t# B

4 h& P2 ^/ G. }! X  W8 u3 f: G  ask roads [ set pcolor white ]
  a, t5 R9 {1 c) @6 s. ~* e    setup-intersections$ `# m- @, s4 e) t9 @9 {4 d
end9 R# Q9 W+ w* u% [5 [) d# S5 B
其中定义道路的句子,如下所示,是什么意思啊?
$ o9 M- O  i, }+ N' ]6 M set roads patches with
2 H' ~" ]7 r) Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 L9 U. @1 j$ g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# B, S- v/ @0 y7 _5 }8 w
谁能帮我解释一下[(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0)是什么意思吗?
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