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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。
( W, b. B" b- h$ F" nnetlogo自带的social science--traffic grid这一例子当中,
+ X3 ^7 U% D# Lglobals
/ ^  N% N% }, Y[2 n; \, D/ t: ]4 N8 P! G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ f. h8 H6 P! [2 a/ ^3 x
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* C0 H- s6 c/ ]+ i5 K8 @; v" k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& b. Q+ ~1 N: l1 \, `                           ;; it is to accelerate or decelerate
( L: {6 K7 F+ B% Y  phase                    ;; keeps track of the phase
/ J; H4 P$ ]5 e- c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 f/ E4 p4 K" K1 ?8 n  current-light            ;; the currently selected light  S6 v; K7 s" q6 s

9 R* F7 W5 B. P0 P5 S0 q9 [9 U/ K  ;; patch agentsets8 N$ ]8 y  S6 J+ _/ p5 p; l& y
  intersections ;; agentset containing the patches that are intersections
7 f9 T8 P! e9 a( O' N4 F" M  roads         ;; agentset containing the patches that are roads
+ z2 k$ `, X6 E6 g0 O# k& g' ]]
$ n6 N& R& m8 {2 b" V& @% A8 q0 [1 ^- G# ]. u9 c( ~+ ?
turtles-own& f: O9 k" h( x  B% e
[+ [' M9 _7 u& P; R! D% l( h
  speed     ;; the speed of the turtle
# z, i" Y8 k( v  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 o/ M+ G' G1 [# z
  wait-time ;; the amount of time since the last time a turtle has moved
) Y3 [& |/ p1 Y]
3 d4 {  T' b( Z' C: u
* T" V! T# g% _. ]) w4 rpatches-own
% k% N3 s- w2 B  _; N  V* u- `! Y[  G# f. N* P4 \6 H
  intersection?   ;; true if the patch is at the intersection of two roads
) m  |/ G* U: T2 {/ ?4 Z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.& K1 {: \. E# y8 g  J+ D, r
                  ;; false for a non-intersection patches.
4 R$ a1 c, G* L0 K' a( c$ `  my-row          ;; the row of the intersection counting from the upper left corner of the
/ \' p  O* G  n$ k* q3 b                  ;; world.  -1 for non-intersection patches.
; W/ U5 G: r& f2 u( G0 K  my-column       ;; the column of the intersection counting from the upper left corner of the5 |5 I% m2 B* }: h# {7 }* I
                  ;; world.  -1 for non-intersection patches.
; f& c( c* D) `7 f$ z- t  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 r$ j( v( M( h2 y, ^7 [6 i3 V2 H  auto?           ;; whether or not this intersection will switch automatically.- Y; Z5 [# f3 n- ~4 ]) A
                  ;; false for non-intersection patches.  \: i3 j/ p+ G2 Z7 {% g% r
]2 m/ T! e; p/ X( t; L

- [* y1 u7 _7 C# f8 t4 N. u) N+ t0 A
;;;;;;;;;;;;;;;;;;;;;;
* ^, y5 h' Q( d, _;; Setup Procedures ;;2 m; _( g: R5 f
;;;;;;;;;;;;;;;;;;;;;;* k/ I" J3 c' G! u3 l* R
' P- {( g! p" J
;; Initialize the display by giving the global and patch variables initial values.
3 |& D, q5 u# L;; Create num-cars of turtles if there are enough road patches for one turtle to
/ ^, ^8 Z1 ~% z! Q2 n3 F;; be created per road patch. Set up the plots.
6 R; Z! D; P0 U! Kto setup
( V) f7 r+ F3 i! d2 }1 w  ca. D7 K1 U) W" {$ `
  setup-globals
; U  x/ Z1 `5 ]; X( s8 Z& p* w) d
* e0 {: K+ `# `; ]# F  ;; First we ask the patches to draw themselves and set up a few variables' T5 D/ ~& S0 M( P5 F9 F1 p4 k
  setup-patches0 F# }0 x; i; j9 ?! }
  make-current one-of intersections/ I9 ?5 E9 x8 o* P4 n
  label-current
, j: R$ ]: T& H- O" s& t
: t. c0 c2 a* u: p( E+ g  set-default-shape turtles "car"
% O4 I, E( c# q% M- p1 V' e7 ]/ p4 T, l
  if (num-cars > count roads)3 n% j2 {, D1 Y) U9 ], x/ M; [
  [  m! _! n4 I( _6 S8 }
    user-message (word "There are too many cars for the amount of "
: h! O$ m: d2 Q4 e$ J: }9 M                       "road.  Either increase the amount of roads "5 q6 Y+ n7 H6 F
                       "by increasing the GRID-SIZE-X or "/ u( H3 g% ?0 g" C7 g
                       "GRID-SIZE-Y sliders, or decrease the "* k+ l# E3 l% G
                       "number of cars by lowering the NUMBER slider.\n"7 t, S2 R: E+ C
                       "The setup has stopped.")
& f& X6 J1 k% k; _- q+ c" O" W    stop; W. U$ n3 s, h3 G
  ]2 O6 D6 Y  {$ r4 ~9 b) `) Q, ]
/ ^" z/ g! ~# K7 r
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 c; g0 {( W& R/ U! s9 E% w
  crt num-cars& }9 ~) S# i! B" I
  [; Q% j. t+ Q, z5 C
    setup-cars
2 H, D* I( w" z8 M2 H( D- Y    set-car-color
; `: D. B. H0 U' b* o8 p# \    record-data
- l2 d9 C" P( S3 W; Y) Q* R" u  ]
; L* a; d5 P9 O# U% T0 `& C: H) k& r
  ;; give the turtles an initial speed0 c: P8 t, k& h
  ask turtles [ set-car-speed ]
: F9 s" E9 p- f' L: j& ~. O3 L& h( g; c3 B1 _8 f7 ~: N
  reset-ticks
' K' V( U6 u8 t: q( J# v- `end
7 P" q; j1 _) P0 [: n( b
$ `% g: @/ M& z2 K1 ?;; Initialize the global variables to appropriate values
6 M  P6 S- f  I6 r; r1 D5 D) xto setup-globals8 \# I  y8 L! a, z/ [& A
  set current-light nobody ;; just for now, since there are no lights yet
' `$ _9 `( x; k! C3 U% I8 J" T3 L  set phase 0- {9 \1 L" I8 s
  set num-cars-stopped 0
0 o$ i& T( v1 E6 d" T  set grid-x-inc world-width / grid-size-x2 B- t3 N- _2 _5 ?! Q- ~( @$ ^; R
  set grid-y-inc world-height / grid-size-y% @9 U; w8 j$ Y9 |' \& y! ]

2 ~  ]  d8 _9 w! Z1 o, M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 p8 @$ U8 R2 W2 Y4 a# v# }
  set acceleration 0.099
5 T4 N4 z! ?) ?' ~+ i7 u8 ~end
4 V( b& i! L+ X3 S& L
9 ?) Z. e/ `% P$ W) C2 L* r3 x% Q;; Make the patches have appropriate colors, set up the roads and intersections agentsets," U1 k6 m% M5 d- [6 p4 c1 \
;; and initialize the traffic lights to one setting' G  S2 u6 K! K. z, j& R! K
to setup-patches
9 O( t- S% g4 {( X' Q  ;; initialize the patch-owned variables and color the patches to a base-color3 w8 Y" c2 H" \3 y
  ask patches
+ K8 m. s8 w/ A1 z. O& ]  [
* A! Q4 }7 x& q/ v$ p. G$ F    set intersection? false8 ]$ W( _* ~* s
    set auto? false+ T0 ^6 n/ E( X" G0 G+ |
    set green-light-up? true/ ~$ P# P* r, Q
    set my-row -1
  u# ]  g2 h# Q5 |# d    set my-column -1: V5 O5 O* O; T+ G. W
    set my-phase -1' V; W' }' Z1 l' n4 {
    set pcolor brown + 3. [$ i7 c5 P, _* w! e. u* O5 m) P
  ]. T: z$ d1 B- H8 H" p0 e- r

7 P4 ?/ b+ E8 ~  ;; initialize the global variables that hold patch agentsets
( U3 K( d5 X/ J  set roads patches with) k" o9 q7 X; |. [# e9 y; P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 h( |) ], `. q9 p2 z% s, v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* C% l' t& D4 M: [2 w  set intersections roads with
; N9 M8 L" U5 T) b; U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ H7 `3 u4 o0 }1 h# ]& o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 @$ \* X" v: g% v: w& Q2 V  _
% a9 T; G  m! P7 s, e
  ask roads [ set pcolor white ]6 V2 Z' a6 `$ E
    setup-intersections3 q# E( k) S* v! W* C
end. \+ C. @* o1 l* }. c: [
其中定义道路的句子,如下所示,是什么意思啊?! L1 _3 J$ r1 s4 o6 t
set roads patches with
1 u& ^5 o% a$ m- b( X4 B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ x: c3 j& q9 t4 F8 \; D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) N5 o. s% X+ V+ d% o# e) X
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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