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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。# D& R0 F, z8 A/ |- h  n
netlogo自带的social science--traffic grid这一例子当中,
/ y2 f! Z9 M2 D0 b4 C: E7 Hglobals
# f9 ?+ c1 e7 N  Y$ k8 P[
8 d! g, r  w% _  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 }: q7 M1 p/ r( @4 W  w7 z/ P  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 u# m: ~9 o. `3 S) h
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 L, ?! u6 y: b7 C6 t+ {2 j
                           ;; it is to accelerate or decelerate
2 X5 i8 P4 l* ~  phase                    ;; keeps track of the phase
$ o# J/ \( w; Y' T" _. j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% L* K3 v$ a; L  b
  current-light            ;; the currently selected light1 S5 \8 D+ K% Q- b* B

; K4 q2 d- Z3 s* \2 \. U  ;; patch agentsets, t! p/ @9 w% T2 O7 c
  intersections ;; agentset containing the patches that are intersections
3 k( k, l& N! M( G( M  roads         ;; agentset containing the patches that are roads
, W: C. K% r( ]# z. a) d& ?]- V' w8 o; |) Q+ p+ W4 h/ o

' T1 x2 e) j, L& }9 {$ {- xturtles-own
" g& P$ b+ V0 C/ ]0 D4 D% _[& D, j% D( \2 B2 N& F
  speed     ;; the speed of the turtle0 Q8 M1 ~# t$ J
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 Q, p* y* |3 x) @  wait-time ;; the amount of time since the last time a turtle has moved
8 p* q* E+ N% H& C]
! H* N" e, f7 A  v% C5 |' F
/ j# {" P/ g- J4 v; Jpatches-own
6 `7 }8 v6 J& D2 E1 J& m[
' K+ _( g6 \* \& |% C0 \, t  intersection?   ;; true if the patch is at the intersection of two roads
; i) L. {4 V2 \$ z6 j2 v/ f1 g  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ P1 l, t+ Y' q4 M+ L7 C6 M4 K                  ;; false for a non-intersection patches.
# P/ P5 T7 M' r: i$ [% h  my-row          ;; the row of the intersection counting from the upper left corner of the
2 c; F! w$ N9 _/ ^8 D8 N' @                  ;; world.  -1 for non-intersection patches.
1 m' E8 [  Z. `  my-column       ;; the column of the intersection counting from the upper left corner of the
3 B- q0 |- }! N% M: h                  ;; world.  -1 for non-intersection patches.* k1 d6 y" `: ^: n+ I6 c/ O4 g# p
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
2 |! e. B! t, W7 I) J6 r4 f) J  auto?           ;; whether or not this intersection will switch automatically.
" A5 V* H% Q) s3 f% s- m4 m                  ;; false for non-intersection patches.
( [; r& G9 |4 a4 i8 R0 i, y' T]6 H7 z. E  i: V4 b
6 C' v/ N; y! Y# J  [

, O, B1 l$ t' @" `' n8 R;;;;;;;;;;;;;;;;;;;;;;
, K, C- {3 p2 T5 G$ b;; Setup Procedures ;;
' h8 e( C3 d& i, U;;;;;;;;;;;;;;;;;;;;;;
; P- ~& `6 N' ~8 ^$ t0 k0 ~9 m  d, C- g
;; Initialize the display by giving the global and patch variables initial values." n4 p5 ?( r# q
;; Create num-cars of turtles if there are enough road patches for one turtle to
' A& [. r7 f+ b( ^, x- L;; be created per road patch. Set up the plots.
6 J6 |" Z1 Z! _) \3 W* Mto setup
8 n& K/ }& Q& T) j  ca: i6 }7 x$ l$ t  s1 d. R) f2 P' g
  setup-globals
* Z% A5 a! J2 S5 b+ r  A! r  v0 [1 i/ T' D8 Q, _
  ;; First we ask the patches to draw themselves and set up a few variables
' K4 |0 b* X) |  setup-patches
8 ]- c; e' M: r: G) @/ a$ H! Y7 G  make-current one-of intersections; f( O  A7 ~' b! |* v' ]% x
  label-current1 L- k0 ?7 E9 M5 N* A5 ]8 r
+ I- h# Y* b0 d) m- M
  set-default-shape turtles "car"
5 E1 h7 t* ?4 h  o9 V3 [5 z9 R' `; `
  if (num-cars > count roads)
* V0 i- l. p  v, N. r  [
5 K) Q' |# u9 f5 h, A    user-message (word "There are too many cars for the amount of "
: n) n# A: I9 _9 }5 P) y( }7 V                       "road.  Either increase the amount of roads "* g6 G; o, }' L, c9 f% y& Z8 i
                       "by increasing the GRID-SIZE-X or "
) W; G% z4 @  H                       "GRID-SIZE-Y sliders, or decrease the "; M" j" j/ ]$ M7 H% F( ]
                       "number of cars by lowering the NUMBER slider.\n"
! Q1 M, r/ {' V                       "The setup has stopped.")
' u) L/ @5 ^" l: i: [7 q    stop
$ j. Q8 o; S. e5 T4 B  ]( ?; O' ]" Y# R: Y/ s

* |( n/ C9 D" S/ u  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ ?. K0 D0 w  X3 S1 q1 T  crt num-cars; k: q, ~, V6 _! M6 v
  [" D1 f9 r/ D: z* w- u
    setup-cars6 k3 {0 x+ n0 f; c# g2 U, q! u
    set-car-color0 c# m6 w! a& C) L( {' S
    record-data
! J' `8 n6 _" q1 w, W! }/ d4 ?  ]
1 [4 p3 G# H- N1 j8 }% E$ W8 L
& q1 P& j4 W3 B% a* j  ;; give the turtles an initial speed4 j: Z% X4 g; d" j8 r" B. k
  ask turtles [ set-car-speed ]9 ~) p6 K9 u( J1 m! j

: r( u7 p; z4 K) B6 `! P! S  [6 R  reset-ticks+ v& B6 z: U- B$ d; p. I7 x8 q  `
end1 u3 N3 ~& x1 ]$ ?2 V& j
- H# B+ _  x3 g- [6 M# y
;; Initialize the global variables to appropriate values/ z. Q: O0 }: U" g
to setup-globals
3 K$ l' B  O. C& b; ?& m( X  set current-light nobody ;; just for now, since there are no lights yet6 L( X" l/ H2 U8 p
  set phase 0
$ X/ n! g  q4 }8 W- s  set num-cars-stopped 01 _0 v& `0 F) P( V; f# J' q
  set grid-x-inc world-width / grid-size-x! h, ~2 l: B% _! e
  set grid-y-inc world-height / grid-size-y
3 {1 \; ]5 R& I5 N* z
* n/ {4 X& G3 a, [2 K4 j/ J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 O' m; z9 J5 N( q; @$ V  ?3 f' i
  set acceleration 0.099
# C/ F3 f. C  Aend8 b* X6 I! ~/ T. V' y
' C$ i4 v" o& ^' P: h" V
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; U5 H6 a; ?  B; S# I6 P$ z& o. |;; and initialize the traffic lights to one setting
# b$ y/ C9 ?) _7 f. L8 Sto setup-patches7 I+ m  Y8 s% q% X
  ;; initialize the patch-owned variables and color the patches to a base-color
" v! G7 _* b/ `& x  ask patches
( r$ m, ^" w$ z% I+ E$ q. Q  [
( k2 i- J8 J' K1 p5 p    set intersection? false0 H. b7 S9 t8 ^. i% z
    set auto? false# D: y. u" s! T' s
    set green-light-up? true
$ K+ i% E+ T0 ^7 I% [. ~0 Y    set my-row -1
' l  S* Y* h, g) X1 w    set my-column -1& V! y. ]  B) [2 y$ E0 l. p& X
    set my-phase -1- O3 x8 F# O; C: v3 O
    set pcolor brown + 3
4 r$ G9 |5 R) I  ]
, B. p; U; b( r/ l* |& a9 A3 h, ~+ y8 C& x0 ]! x
  ;; initialize the global variables that hold patch agentsets  w: M6 }! p$ o) c9 b6 [! n
  set roads patches with! |2 q( O6 U9 A, |! u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 M* [! \, K, C) n7 S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 a, k9 A) q/ P8 ~  w7 u
  set intersections roads with
" J. m/ ~- L4 f& A" M5 v1 G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! e% w# ]$ P* J" \( j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% E# ^1 D' n( z5 x2 k1 \+ {+ N. d% s! j% M

$ `7 f0 `# M/ H' j  ask roads [ set pcolor white ]  l1 O  B% S2 G, m5 c
    setup-intersections& v4 \  e* D2 ^5 _! X  r( `
end- i* m: _3 F7 O) e3 b/ ^  ~* }
其中定义道路的句子,如下所示,是什么意思啊?; A9 o& p( j5 G  M9 [. b$ Q  [" n
set roads patches with) m* l! g8 |! D# Y2 G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; V+ }5 h2 f$ o! l5 g: G1 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. r, u7 C. D- R8 M/ A$ A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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