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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。0 ]+ k3 s0 Y+ @! M/ v9 @
netlogo自带的social science--traffic grid这一例子当中,/ ^, l1 Q8 U" F2 i6 _! J- D
globals
/ H* O& ]* y* W# x[5 I& b2 {" T  Y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 d$ B" n. C3 h+ q, Q" G7 C' _6 U& }
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 A: e" ]! I) l1 }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 h, t) x; O" w+ y- _* D                           ;; it is to accelerate or decelerate
1 }6 }3 |: E3 B7 k4 z  phase                    ;; keeps track of the phase
: j2 G7 [4 f4 _" W& H  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 R$ b" Y5 a2 v$ C. Q/ i. R  current-light            ;; the currently selected light
# H# e% T4 s8 a8 e
6 N0 X% g1 Z$ B" H6 ?  ;; patch agentsets: {9 j8 F! _; w2 R* W, s
  intersections ;; agentset containing the patches that are intersections. I  X( f7 l$ a' i! v, \2 n
  roads         ;; agentset containing the patches that are roads; A* I+ w* e: B7 ]
]
0 L4 Q- r& n( r* I" q; I: H' h: O/ s- r+ a1 s8 R6 U0 f! o) s
turtles-own
* V5 k% D. [/ t[% _9 T! v+ K% ]( t+ d8 C6 a
  speed     ;; the speed of the turtle
1 u/ n" d. M, j8 w8 i! l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) V/ u: M6 @4 l2 P
  wait-time ;; the amount of time since the last time a turtle has moved
9 o! x# y/ b! j8 n1 _2 B3 D]  p' V  X9 b+ N

  C( b6 n) `. x# g6 a* m- A" L* m9 Upatches-own! }  T2 f  J1 [. H. G- v
[
  d* O. E7 w% A' N; ^. [  intersection?   ;; true if the patch is at the intersection of two roads1 t+ f8 @$ ?' [' [
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 a' ^' {! D" K1 w& W
                  ;; false for a non-intersection patches.4 H/ J, E5 y$ w6 a) N$ D
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 H  ?' |3 q# p" v) p9 q, D                  ;; world.  -1 for non-intersection patches.
7 l3 i+ K2 ]" e" a, A) d# |  Q' f  my-column       ;; the column of the intersection counting from the upper left corner of the3 u( j# q$ `4 e: L  p* N( @7 U
                  ;; world.  -1 for non-intersection patches.
9 O, c/ |, _, a' M( ~2 H0 o6 n8 x  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& V6 _1 i1 U' a9 r+ H3 p  auto?           ;; whether or not this intersection will switch automatically.6 ~& b- r& X* w9 ^) |! p
                  ;; false for non-intersection patches.
- c0 m( a" ~! Y2 r]
1 X. D3 t. c: L8 P& Q! _4 }: Q2 K& H/ I, {
5 H2 K5 p2 a, |. Z% E
;;;;;;;;;;;;;;;;;;;;;;6 j; q: ]+ B% c" ~  z# ]1 Y8 M
;; Setup Procedures ;;$ D! z7 y' Q+ g4 ~/ v3 t
;;;;;;;;;;;;;;;;;;;;;;0 u5 ~: y  b! B( ]& @. l( K
# i4 W$ i1 @/ E9 c
;; Initialize the display by giving the global and patch variables initial values.
/ u8 A3 y5 O( ?2 {' ];; Create num-cars of turtles if there are enough road patches for one turtle to# X, X" |6 n5 o: O( O8 r' b
;; be created per road patch. Set up the plots.$ @6 K0 U" f# A3 I% \
to setup9 W9 I. M: S1 \9 R$ {3 F
  ca
# W5 j( ]8 d4 w6 E3 r8 y  setup-globals* }; d$ M) j0 ~1 T
- g0 O+ f+ V2 o% x$ X  c+ c
  ;; First we ask the patches to draw themselves and set up a few variables
4 Q/ t9 L! K  r% l9 S' }& X  setup-patches
  Y0 s' Y( ]  z9 R3 N3 m: b( k; R6 k  make-current one-of intersections; l4 _  ~( i  v3 G
  label-current# B* V. x! l9 {
3 w/ N  j2 H& D
  set-default-shape turtles "car"
$ O& K3 E: n1 j" B5 Q" i
: x" d4 z$ j/ i( G$ L  if (num-cars > count roads)
0 h. h: z- J9 K  N3 t  [: W( k+ i3 [2 h" a9 e7 \
    user-message (word "There are too many cars for the amount of "! J" {0 g- x7 g* C5 `# h& Q
                       "road.  Either increase the amount of roads "! [( w3 K( ?6 x
                       "by increasing the GRID-SIZE-X or "
. Q- C2 t' l5 i  ]                       "GRID-SIZE-Y sliders, or decrease the "
/ E& \8 J# S5 |0 Y( T) ~                       "number of cars by lowering the NUMBER slider.\n"9 E: a) q+ }6 V$ \' \8 N# V9 v
                       "The setup has stopped.")% F1 o  M: f" F! t/ \# K, T3 \' E
    stop
* B3 o" \, C7 m. w  h  `- h  ]+ ?+ E% S: O6 b& S) b
- [( @& y+ R9 G& J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' E! j6 L" D- e, j, V- |& A# h2 V
  crt num-cars& ]2 j& o( l3 l- C/ Z
  [
3 Y" P8 z: v, U5 L- Z' U' F    setup-cars( }7 u$ X$ }% D7 c1 F
    set-car-color3 k) m' E0 Y8 D4 e7 `
    record-data/ M5 B& b6 _! P" n
  ]8 n3 V! ]. i/ y9 X* y# i

$ L6 r6 e0 ?5 h! ~  ;; give the turtles an initial speed3 w) }& u( O' f6 G
  ask turtles [ set-car-speed ]
  o3 f. z0 b4 ?6 s& d
5 f6 C6 S" ]0 Z  reset-ticks
' ~4 S9 d# O) ]( ]* S7 Zend! n& ~1 E$ z! A# B& f1 K

3 I; m- ]: U- c/ s" M6 M;; Initialize the global variables to appropriate values
: J9 ^( J  o9 P% Mto setup-globals* C$ F7 M% B. F) M
  set current-light nobody ;; just for now, since there are no lights yet7 c" ^. q# W) H3 x9 e" v# p
  set phase 0
( B" O; l% [8 d7 V, R# q% u8 g  set num-cars-stopped 03 D: A9 W& V% S
  set grid-x-inc world-width / grid-size-x/ K. q4 O& ~5 H' A( P2 p- |
  set grid-y-inc world-height / grid-size-y' y& _5 E( |2 q0 C* _' H* C

& X$ Y: A6 k6 m9 j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 _# ^; B& j2 b8 \  p- K4 Y
  set acceleration 0.099/ e; [/ G" O; ?2 q2 [/ w
end$ ?, y& Y5 X+ r; u3 o/ K* R$ Z

2 A  R+ @1 t+ k1 }; j: t;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" l; G; |+ l: a/ w0 s9 P6 @;; and initialize the traffic lights to one setting: I. D* q- M8 n; e/ u4 U" e
to setup-patches
- J/ ~6 V4 [0 f8 Y  ;; initialize the patch-owned variables and color the patches to a base-color
" u# W1 ~8 I& j; l4 }, ~' U3 |7 P  ask patches; J7 k6 f3 X8 k% }2 e
  [
- Q  b; B: @3 Y6 y; y& {    set intersection? false
! ^% D4 f1 p* G4 K& m9 P$ Y    set auto? false
/ b' a9 b+ ^. E" _; R  a    set green-light-up? true; g, n4 ]/ Z, b% |# F4 g2 t3 L
    set my-row -1; g; ?6 Y( E% D. ^" }" O$ [+ f( e/ m
    set my-column -1
  Z  x* g% N, H2 w& ?( e9 K2 Q+ t    set my-phase -1& R1 Q) c3 t! G$ ~- `; }7 @: i2 d
    set pcolor brown + 3% d# Z! L4 k6 U, n/ A
  ]
9 k  s# ]. t% _0 H* F) P! C8 }% a% T+ X) X1 x7 [6 y  h8 B- ^+ D
  ;; initialize the global variables that hold patch agentsets: f7 c/ A; L* b" ~6 y4 x
  set roads patches with1 w2 h" G, t6 N" M& G5 E. T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 l. n# P2 z0 p3 L/ @4 r4 r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ m* t8 B, L; C  d
  set intersections roads with6 `+ k0 I- A& ]! l, B% b( D% i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' V- i* q% F& z7 A& U/ |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 S5 s& h3 f$ J/ L& L

# `1 a( c9 p. n! a  ask roads [ set pcolor white ]
  \7 b( X; r1 u% m' s. E$ t    setup-intersections- m% V7 P4 f  a
end* E# r. c/ i* i! z8 E* n. H
其中定义道路的句子,如下所示,是什么意思啊?5 s! t' o# ^, v$ A2 F0 k
set roads patches with/ u2 `! Z! a) U0 x( e' `& [; m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, k9 x; d8 |# {6 Q7 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ K; b7 \# _1 g) @, N# J
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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