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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。
, C- I) d8 }2 `6 hnetlogo自带的social science--traffic grid这一例子当中,
% u- k$ J: D+ c5 J; N6 W9 Nglobals& J9 D0 \) c1 h5 {
[
/ s8 T  ~2 e5 Z3 [  H5 W  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 r, s3 Z  ~/ ~! X( D" E0 e  grid-y-inc               ;; the amount of patches in between two roads in the y direction, E7 I# [2 N* b" c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* h% ^5 S; }3 K
                           ;; it is to accelerate or decelerate
, k6 C: {7 p1 C) W: u  phase                    ;; keeps track of the phase
! D% v- h; N9 w' I: u) \  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ x7 d/ n$ `, s7 ]% V( B
  current-light            ;; the currently selected light9 t" O/ K  ]5 F4 ?$ b8 D7 R2 U

' l; Q- c5 m, j  ;; patch agentsets9 R& n) N+ d0 `$ o# p, V3 n
  intersections ;; agentset containing the patches that are intersections  Y, O( q' d2 T  s6 b6 t
  roads         ;; agentset containing the patches that are roads8 {8 T: f( P! F6 ]5 W* }- G% I
]4 o/ L0 H6 h; @9 `
' Q. w7 X# [* }! h
turtles-own
3 x3 I8 B5 G' K: F$ ?* d) ][% x2 S* ~" V4 q& m8 c
  speed     ;; the speed of the turtle: s6 i2 a4 C$ J$ m9 y( \. ], E
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right4 B- Z$ l- y1 ?$ u: U1 s/ i; a
  wait-time ;; the amount of time since the last time a turtle has moved: B' {; `$ i" g/ G6 M0 J; @' Y
]
* m6 ?4 R0 O' O; _; E: X! E2 A! B
patches-own
  v0 \: d3 X& \1 {" G+ I5 w, |0 M[/ D; k) H2 m9 U6 R4 k6 q
  intersection?   ;; true if the patch is at the intersection of two roads( }- ^) H/ b+ n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ {; x2 y. y, c2 x9 _7 a0 t
                  ;; false for a non-intersection patches.
3 B) q7 N2 z9 u; t0 u  my-row          ;; the row of the intersection counting from the upper left corner of the
$ B5 s$ l9 D$ v  b" @                  ;; world.  -1 for non-intersection patches.0 O3 ]7 i% G* d8 _4 K& M. ~& m
  my-column       ;; the column of the intersection counting from the upper left corner of the
: s! g; ~& y+ L. b4 L- I  |                  ;; world.  -1 for non-intersection patches.
) C0 D( Y3 P9 ?0 n. x0 k  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.6 c+ |- _' S0 l0 u) }
  auto?           ;; whether or not this intersection will switch automatically.2 O1 j3 ^% ^+ P3 Z/ I# d% O- C
                  ;; false for non-intersection patches.  U: o# X& o2 A' ]# s
]2 A. }" A8 s" f) G1 O" Y

+ e( v2 m- q, T  o4 h
6 u% u0 w2 ]% X1 T7 `) O' m;;;;;;;;;;;;;;;;;;;;;;
7 p0 o2 {: d& t; S, `- k/ L, E;; Setup Procedures ;;
9 T5 t3 v4 [# j: };;;;;;;;;;;;;;;;;;;;;;9 E  M8 L9 {% t' \: Z% Q4 E
# g8 J! R4 C0 u7 u/ h! y0 r
;; Initialize the display by giving the global and patch variables initial values.
9 _, l) o+ O/ _1 J7 w;; Create num-cars of turtles if there are enough road patches for one turtle to
$ H8 y& f/ v/ g9 T9 q0 B;; be created per road patch. Set up the plots.
. T% t, t; ?9 wto setup4 ~. A& o  L5 P! r1 W3 q+ `3 _* h
  ca
+ ~8 }+ p1 J# v- Y4 S  setup-globals
# i0 d  y+ }1 d0 _- ~3 w- c) h9 u- Q) Q2 u) E3 a0 d
  ;; First we ask the patches to draw themselves and set up a few variables3 ~) c$ U2 m0 J
  setup-patches
$ x# b  w% ^, c- f6 V  make-current one-of intersections  \9 ]/ p& A0 d# s1 j) X
  label-current
- t' C5 T" S0 I' g! s0 F7 _. S6 F6 {% O; }0 i
  set-default-shape turtles "car"! f0 }1 C+ d" e; g
6 M+ s3 V% s. \8 Y
  if (num-cars > count roads)
. t; s  N% b; f  [
( |' |: G7 P$ [8 p5 f9 k# c    user-message (word "There are too many cars for the amount of "
- n2 G0 n: Q) ^# }- x. g! j                       "road.  Either increase the amount of roads "  w; ]0 b( B5 F' S' D
                       "by increasing the GRID-SIZE-X or "
' j. `; |) ]+ p1 W8 h1 z) M                       "GRID-SIZE-Y sliders, or decrease the "+ o& O5 A  L+ Z% ?* v
                       "number of cars by lowering the NUMBER slider.\n"1 O  |: u1 r4 ]0 R" A
                       "The setup has stopped.")% T. D% U& L6 C; F' C; E
    stop* U! F- T; q" ?! ]" i6 Z0 O
  ]
4 S  U& }9 Z- f1 }0 U0 V" F4 F4 T, A5 x* S) ?
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ `( `( u' e# x( D  crt num-cars; [$ A; @+ N$ I& Y5 R1 F
  [. K2 ~  x3 Y1 ^4 w4 I
    setup-cars
( S8 a& {+ Z$ |& C/ B    set-car-color) Y2 p- T- C1 Q
    record-data
2 ^7 b+ V1 T; Y% s% u: `& n  ]
& k* X9 J3 W: l7 I: P+ \$ V' {6 K: B, Y& s5 |) @- p
  ;; give the turtles an initial speed0 Z6 i+ G- x1 ^" V
  ask turtles [ set-car-speed ]8 \. {, G6 E& Z$ A- C

* R- }! A: L/ @. K- N5 E  reset-ticks
: t. ~% x4 d+ w" @- x9 N9 |end
5 T+ {% G$ e2 H% z' V5 r- u% H4 l; k8 y% Y! K6 M# W1 A: ?
;; Initialize the global variables to appropriate values4 V3 _* w0 \2 l' \6 b
to setup-globals
, n, q; b7 P. c2 X  set current-light nobody ;; just for now, since there are no lights yet8 C. p( |. B( x7 [
  set phase 0  D: V* r: R$ g! G. a" s3 ]
  set num-cars-stopped 0+ t0 e) \& S- @/ G$ ]$ [
  set grid-x-inc world-width / grid-size-x+ n1 W: p- I6 A! @) H' P; X6 w' Y: S
  set grid-y-inc world-height / grid-size-y
/ K& k4 D6 e' E! y8 i1 ]' I  z3 d
% R) ]+ D# Q/ H! j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# Q9 i2 E. a2 R9 Y" L) T5 p
  set acceleration 0.099% `& R" n" g- }/ v  |' N# f+ W' K
end
( X( o+ n9 r) v+ B: T: \+ {1 ^, m9 A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. X+ D5 o; \3 t* B;; and initialize the traffic lights to one setting9 |6 t' B- X/ [( ~) Q0 Y
to setup-patches: y; A" ?$ u; Y- c1 L
  ;; initialize the patch-owned variables and color the patches to a base-color
  `8 h4 P, N$ p6 |* o( E  ask patches
2 @# c# K% \9 ?- N: Y  [7 |& h7 a$ j. A& U, V! B8 M6 M
    set intersection? false+ _: @! y1 }3 a! G: w
    set auto? false
1 l9 q. {- {( C$ a    set green-light-up? true
( g: H% c6 Z4 r$ V    set my-row -1  I( o4 {- ^* l/ B
    set my-column -1
$ y5 r0 D- v: a& j  `    set my-phase -17 F# A$ ^9 `2 U8 L: [# k4 Y3 Q" M
    set pcolor brown + 3
# T6 p: ^1 R% G9 U& F/ _& H  ]) U& P/ k3 w1 ]# ?$ g  ]* R

' T- n3 Q2 j) d$ ^0 ?8 W  W  ;; initialize the global variables that hold patch agentsets
9 @" t9 n9 V8 X$ B6 O7 V* W* M  set roads patches with* F; N  z3 U2 f/ L, i- G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% ]7 z: u) u/ m% M, R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 L  ^3 C7 E- a+ V! o. `7 B  set intersections roads with
- Z$ u5 J+ E3 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- g# V* `$ z7 w! o2 d' m! W$ Z  w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], W8 ~4 q+ P& O9 X3 v/ G' I6 j6 D

& m0 g1 G: m8 Q+ z  ask roads [ set pcolor white ]
1 `1 O7 z7 O4 O4 y7 Y8 L& z    setup-intersections
4 o4 k' k4 ]7 l) t: O% [end# N; ]; E: }3 e7 E: s+ L
其中定义道路的句子,如下所示,是什么意思啊?
0 z' a9 a# q1 x& H set roads patches with- f/ u4 H- }3 W# ^; }# y5 G: ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 k( _6 }  r4 x7 `/ y' a/ g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ ]  E/ x* i! v: b- J' D: `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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