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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。$ j0 m8 ]7 |) r- {7 W
netlogo自带的social science--traffic grid这一例子当中,# z0 F9 `; x4 C) k3 L
globals# L5 q5 r# {* W; B. b$ x: w) M
[0 b' q3 j9 A, ~8 B8 U8 ~, C
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ K0 [0 |7 i" p+ m3 s  U, E4 n: `1 P' ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction- y+ {9 }; r! |/ q. k
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! v9 Z) q' C1 S$ D, Y                           ;; it is to accelerate or decelerate! M: [8 b5 M% |" G6 q* Y: E
  phase                    ;; keeps track of the phase- \8 W4 T2 H! Y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ v, b6 K2 }8 {, O7 s3 F  current-light            ;; the currently selected light, e2 ?7 f3 k9 c
& s' W# V" K  s# N
  ;; patch agentsets1 q- J$ K" ]/ x8 `5 I* _6 e6 y6 q
  intersections ;; agentset containing the patches that are intersections( d/ k' s$ U( P
  roads         ;; agentset containing the patches that are roads
( f% t4 B% j  w7 X% _]( f. k0 |8 U1 Z4 K' Y

% m+ x# i3 v' z9 w3 A+ k1 fturtles-own' f! r  b6 p* X% R6 L
[
  ?5 a- w# K: E: p  speed     ;; the speed of the turtle  _0 q1 C. n9 y0 C# m* H5 @* Y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right. H$ c" ~- b! a
  wait-time ;; the amount of time since the last time a turtle has moved
% U+ A4 M( M7 z9 @]
7 i. v" O# w% E6 l
% X9 y4 H  h- Z/ Y: i5 Cpatches-own  H8 J4 P3 N4 g+ X6 c5 `* ~
[. F, w2 G' O0 H! `% k
  intersection?   ;; true if the patch is at the intersection of two roads
7 V: I1 _  ]. J* ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ `0 F  ]. [* U
                  ;; false for a non-intersection patches.9 _2 p5 {; u$ u9 G) `+ P7 a
  my-row          ;; the row of the intersection counting from the upper left corner of the
) k% `2 Q. O4 Y; F% m7 |8 R; @                  ;; world.  -1 for non-intersection patches.
' @' o2 ]1 {9 e7 z! B  my-column       ;; the column of the intersection counting from the upper left corner of the
8 K; m$ A- [& a5 h. p% W' N                  ;; world.  -1 for non-intersection patches.
. I/ S2 |4 E# a# a: C  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 O; y, B0 |. `  ~9 n
  auto?           ;; whether or not this intersection will switch automatically.; X; e, m! p/ f. I% I! ~# A' n
                  ;; false for non-intersection patches.
9 A2 z' [: Z  Z* D/ N% x2 C* f: H( N]4 r8 g+ H6 |( `

+ l4 u" F* p4 I' G5 H. ]
* C# o# c+ ~3 L- |: T' V;;;;;;;;;;;;;;;;;;;;;;
5 S' l. @4 c& K' b! E9 L% i;; Setup Procedures ;;
; L- K" \. Q# B: H;;;;;;;;;;;;;;;;;;;;;;
2 B1 E3 O$ S# M4 y0 q/ f& B# R, J5 z
  e: W% p5 ^7 Z) G' j' [& F/ \;; Initialize the display by giving the global and patch variables initial values.' \0 i4 N8 i5 P* S* u( c  U
;; Create num-cars of turtles if there are enough road patches for one turtle to( s3 d( s3 e9 `" W- m3 ]  |
;; be created per road patch. Set up the plots.
0 V# P( N5 M: x" v$ Ito setup
/ `. ]5 B( G9 k7 _; g) a' ]  ca
  B& s( Z  g9 n/ |7 u' C  setup-globals
1 _; L. b; L1 e
# ~2 W, D3 t: G8 ?7 }/ y  ;; First we ask the patches to draw themselves and set up a few variables7 c+ `; o4 L/ n. |
  setup-patches
$ r8 M' V9 b) M. {: \6 E% w  make-current one-of intersections' E5 p; L( _) E1 p+ l) a2 Z
  label-current
4 |0 [4 \: T, X
; U9 ~5 m% g( @( N5 ^: |  set-default-shape turtles "car"  \0 P0 D* |- J& b- a0 Z
3 z/ J: h6 |6 E% f$ B& o
  if (num-cars > count roads)4 b% N  x3 I) K# ^% w8 {& ]6 A. v
  [' ~* R# T- o0 q& N! r; I3 u
    user-message (word "There are too many cars for the amount of "
; X& B# r+ J: q7 w                       "road.  Either increase the amount of roads "  i0 v2 w* F, |: b0 Z- ^- ?
                       "by increasing the GRID-SIZE-X or "5 ^4 T8 F  c: H- w, V* ]
                       "GRID-SIZE-Y sliders, or decrease the "- ?  p" p' s8 ~4 s! f7 ^" x+ {
                       "number of cars by lowering the NUMBER slider.\n"
8 L# b* k6 g+ I                       "The setup has stopped.")) o  P" n. z1 G4 @; J  S3 R5 S; y  X/ q
    stop
- ?+ k# ]% ?& L  ]
5 S9 W) i7 ~; \. ]  I6 V
& h0 f. T, {5 v3 X8 a  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- R4 h- X! I  [2 p- O. C5 l  crt num-cars
/ Z; r# n0 J0 X* I  [% h( c: o, c9 j* t, B
    setup-cars
, n5 N2 A% I# G1 n    set-car-color
) x6 I+ ?: S% g! j3 y8 m/ L    record-data
2 e9 q1 X$ a  C& p' Z# L5 v! l2 g  ]: X5 O" N$ A, D" K& O

% P0 B& g. k/ ?  ;; give the turtles an initial speed) A: @; w4 L$ R# L' V3 V
  ask turtles [ set-car-speed ]
9 X' r0 L7 x% B$ s  [
" M" A; w& v$ E. n# }  reset-ticks
% B+ H1 V6 \3 |6 a- t+ n- F* ?9 [end& r$ N+ r/ ]5 B  C
. {( ^/ S7 N! q8 z, @
;; Initialize the global variables to appropriate values) p, I9 E2 F/ K$ ?
to setup-globals
: g3 N0 U1 X4 L( d+ r  set current-light nobody ;; just for now, since there are no lights yet
% p' ~- |) g- U& ]$ @, N  set phase 0
8 O, e9 J3 v9 M/ x; R  ~5 G$ h  set num-cars-stopped 04 r  ]: ~+ T& I9 k6 W
  set grid-x-inc world-width / grid-size-x* \- c' R7 \0 S2 Y* i" |5 U! ~* G; [  @
  set grid-y-inc world-height / grid-size-y
5 a4 R! L2 S0 |. g5 t4 l7 j4 G5 j& t; U1 ]: i3 F
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 h4 @  |3 d: ~6 \! F0 E  set acceleration 0.099
4 V0 x" M0 p1 [& d* o" j1 zend  J' ?& V& V2 m0 O& A

* Q, }/ v7 m4 T$ {! X0 c; Q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 u" x9 j) w5 F;; and initialize the traffic lights to one setting& m  a8 C) n7 Q$ P
to setup-patches
. ]; o9 z, Y6 [: z  ;; initialize the patch-owned variables and color the patches to a base-color: \3 l9 \. u5 |" o
  ask patches
3 r; F. H/ G4 [3 N& b- M  [, S3 p$ d- e% p9 V6 `- N0 z
    set intersection? false
& Y! P9 g4 n1 M( W    set auto? false* f3 I6 |4 B/ D( y( V) j+ a
    set green-light-up? true6 p8 j2 o4 J6 g" b, v' J6 a# ?4 V
    set my-row -1
7 }8 }2 N! Q: G    set my-column -1# ]5 f, i/ B2 |
    set my-phase -1
, I4 ~$ _+ ]' e' G7 D2 d  y    set pcolor brown + 3) [9 D( r+ c$ D3 y  s
  ]
' k9 c( @: z9 M
& A1 a! k; ^0 F  ;; initialize the global variables that hold patch agentsets" @7 l3 G2 T- ^$ H
  set roads patches with! ~7 F% `9 \. Z0 h3 x6 \4 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& U% S* ?9 O, S- _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' Y- f' q3 ~2 {
  set intersections roads with- e- w2 C$ k1 B. ?1 Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" i, i3 _% j% ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( Q" s& y+ u- t' n

. `, L1 {+ V0 g' |" [8 B  ask roads [ set pcolor white ]+ D# v# K, q. R. L3 A
    setup-intersections
, F8 ?& g) H: u; n; m& ~end( C3 P5 u; m  W3 F
其中定义道路的句子,如下所示,是什么意思啊?
: M* _& J, T# z& L set roads patches with9 m' D+ L/ w$ s" D- v" \0 q0 `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! X- d6 v6 u. b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 s- b8 V" j8 O
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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