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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。* l' h, ^8 d) M1 h2 @# G& P
netlogo自带的social science--traffic grid这一例子当中,
8 b: e9 X# v  Y7 n0 r: g; u& nglobals
' u% w5 Y3 [- e( f[
/ J6 r% U& ~. I4 P& l4 Y7 V$ T2 F  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ T7 ]; v, T3 J( s' E: s" X3 J
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 l% i6 `! T- e5 T% K  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  f$ c; s. O$ \                           ;; it is to accelerate or decelerate  c) Z& R9 d# ^* l
  phase                    ;; keeps track of the phase& K7 t5 j1 ^- Q. v2 N% a
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 O1 V: y  P9 I  current-light            ;; the currently selected light8 Z0 o. `8 H  }; g3 u, y* s. b
' r$ O8 S$ O% U( J( \0 T8 H5 |
  ;; patch agentsets; \, ]9 |& a: q. ~% P
  intersections ;; agentset containing the patches that are intersections* _. A6 r6 Z3 J
  roads         ;; agentset containing the patches that are roads5 T: q# @: R9 L: }
]
* e: v! s- P1 ]1 t' g% }8 v' Q3 P. v
turtles-own
; f6 ?, d( q1 ?0 @( W[* A$ s: }' |8 B1 y" @
  speed     ;; the speed of the turtle
% c7 E' `2 D; i, Y  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 J0 P1 _" _9 k+ y% i* e0 A, e
  wait-time ;; the amount of time since the last time a turtle has moved
( f5 U6 q6 ]7 B: M]3 R8 t/ Q/ _7 `/ _9 H

2 `: J+ G+ I, Fpatches-own7 l8 ]& z, v) _) O' y
[0 g8 {; r" t: U& b" \& n
  intersection?   ;; true if the patch is at the intersection of two roads
/ O$ Q: q7 V1 t5 i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 u- s" P- q; Q: N5 ]* V
                  ;; false for a non-intersection patches.
4 Y* v0 d/ U/ h  my-row          ;; the row of the intersection counting from the upper left corner of the# W$ c1 Z) W7 |% N" S% }5 I
                  ;; world.  -1 for non-intersection patches.
+ o9 p& ~: s. B  my-column       ;; the column of the intersection counting from the upper left corner of the7 X. B5 \5 F8 ~8 A5 K' v
                  ;; world.  -1 for non-intersection patches.
+ e5 L! z7 A' [5 ~5 b  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& s* k* J" x1 ^: b$ z# W
  auto?           ;; whether or not this intersection will switch automatically.8 ~9 U( N4 h3 y" P- g+ K1 z  T
                  ;; false for non-intersection patches.
9 y1 s5 \' F; Y! E& j5 M]  I- H  Y0 h5 Q! i6 }

7 s6 P( ~! ]  \6 Y2 P# A' Y# B4 G1 {3 }$ B/ q5 x
;;;;;;;;;;;;;;;;;;;;;;5 a# F9 @+ W* a' Y1 r9 q
;; Setup Procedures ;;
; j9 c6 J+ Z" D+ P0 ]- [;;;;;;;;;;;;;;;;;;;;;;; A( @+ ]; B. W: n' h
  `7 |/ T. C) ^" @( L. b0 L
;; Initialize the display by giving the global and patch variables initial values.: w/ N! H7 H: {+ b8 a) h
;; Create num-cars of turtles if there are enough road patches for one turtle to7 B* n3 ^0 F* ?8 t; i2 C. T
;; be created per road patch. Set up the plots.) T3 |1 O: x9 c3 D
to setup: B9 R* v# |+ V9 h. O: V
  ca
6 Z8 k. D. M$ {* N) `6 i0 ?4 I  setup-globals, z; A# h2 z. Y. A' A# ]) f
' Y* ]5 V! e* e% W+ ~  K
  ;; First we ask the patches to draw themselves and set up a few variables
4 w/ B  Y$ o: N. ?  setup-patches
" D# ~) D0 z) ^  make-current one-of intersections
% L! @, X+ M  o$ J7 U  label-current
6 X& J  ]' M+ E8 C! v3 d+ ~; M  O
/ L; r9 h& M: L# Y, s+ Y8 Z  set-default-shape turtles "car"/ Z* k" O& v9 g$ Z1 n# n! b% f

$ v% n. O, S8 q# z  if (num-cars > count roads)
) ~. s, \; _" T8 X# I$ u1 e8 Z  [6 {+ K' a6 r$ @
    user-message (word "There are too many cars for the amount of "6 `$ L+ p8 D( f: u8 ~0 h4 b
                       "road.  Either increase the amount of roads "
. s, k0 h8 m, F; E* }                       "by increasing the GRID-SIZE-X or "
: k: U& Z4 C& H5 a! B" H                       "GRID-SIZE-Y sliders, or decrease the "
2 h& E2 d* `( P$ a0 ~, C                       "number of cars by lowering the NUMBER slider.\n"5 e5 P% S" E4 q( i7 x" `6 s
                       "The setup has stopped.")( u, e' k2 E& Y9 S: q  b
    stop
$ R8 i+ Y4 W3 s! c4 u7 o( G# d+ R  ]+ i% V. v7 Z7 x+ `
+ `9 v* Q0 T' {% b! e) I
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 M$ D+ A. A8 i3 @  crt num-cars
# ~. P( P# A& R0 L1 w  [
2 c1 Y3 F- b  V    setup-cars6 Y/ a  |- F- E4 y
    set-car-color
- {' u3 i: E# h4 X    record-data
3 b' S/ _1 O' w  ]
; c. Z% A( v& p# {  Z
! L: k+ E1 Q: T- m3 l( J  ;; give the turtles an initial speed
; v' V$ [; c5 n/ M  ask turtles [ set-car-speed ]2 M1 ?9 m3 Y2 P: d- s; f2 e

- C1 U) p2 {7 n: W9 _- V9 V  reset-ticks, J. @/ s+ X8 n3 [1 M6 m
end9 H$ @- G, i5 t) v( X" ]- G: s3 U$ q
/ [% G7 ?. U) w2 s9 }
;; Initialize the global variables to appropriate values
5 K* M& C0 z9 m* r) z: C' cto setup-globals9 Y) E+ W% q! R. T
  set current-light nobody ;; just for now, since there are no lights yet& A6 q( Y2 T) w( W. j1 y
  set phase 0
( S- y7 ^9 j& j9 \8 v% G  set num-cars-stopped 0
0 z( n) e0 b/ R; c) s3 x  set grid-x-inc world-width / grid-size-x
' v6 _  h8 Q9 Q  set grid-y-inc world-height / grid-size-y& a  O# [: o3 C8 `% l

. P6 w& D  u9 b0 `8 M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 y* K4 p( p1 j; W
  set acceleration 0.0990 G$ h7 I3 [2 e9 @9 |
end
0 r4 B  T$ }8 v7 u) b* w# B2 z; b5 s8 A8 K# ~1 G3 @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,; n# ]" v& g+ p, n, b8 e9 ~
;; and initialize the traffic lights to one setting9 ?" g  h6 K- P8 }8 l
to setup-patches, \' U+ Q; k2 b9 ~- e: V' i8 V5 g
  ;; initialize the patch-owned variables and color the patches to a base-color
2 t: d/ C4 t3 ?$ n$ I, X  ask patches: h6 X7 `% |- V3 _; c
  [6 u# {+ ~; j) V6 i' _6 N4 [; k
    set intersection? false
; X, p2 f! |6 g    set auto? false
0 f2 v$ {, W8 X: S    set green-light-up? true5 D6 i: K& o& d
    set my-row -16 [# r: k2 h; ]% B" B
    set my-column -1. T3 Z" `. e5 t# @
    set my-phase -1
4 ^4 Y& ]! `/ G    set pcolor brown + 3/ _$ |5 g$ e" Z. e
  ]2 s2 A+ M; C/ m( y

, N6 |5 W/ d5 l9 R  ;; initialize the global variables that hold patch agentsets
0 b! l  z- ^; M6 Z  set roads patches with
# ^; i* a# Z) v, l  z" g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; H/ M' a& l- X- Y! H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ y3 r6 K1 Y5 p: A& E  y4 O  set intersections roads with8 D% `4 \. u4 ~5 x/ ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! J& {7 b$ G. w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- E- M/ B, S% {% j- e  w4 C8 N
4 P* Y5 Z( T, S! r
  ask roads [ set pcolor white ]4 p6 y. S8 C) H' J1 p1 K! H! z5 t
    setup-intersections
0 o$ f3 K! p8 n4 a; h8 Tend
- F! O; l/ y7 R% J5 o* D7 N. `其中定义道路的句子,如下所示,是什么意思啊?
; Q" p6 G9 L  U  D6 N1 a4 K set roads patches with1 J! b. z1 `% m" ]! t* }; D+ b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ l& s+ o  e. S1 a8 g2 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- s; L0 l1 {- s
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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