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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。
% d4 Q, W' M7 }# H: T# c+ Lnetlogo自带的social science--traffic grid这一例子当中,
8 x  X+ k% V- i& ]$ Qglobals' c% {3 `5 b2 B7 X6 l
[
7 e7 z# q! y7 J' f! u% O  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% X9 m' N- v5 z# f2 U, [% Q4 |  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 ]4 I% v. Y# O; ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ g8 G( G0 S6 \* B; ]
                           ;; it is to accelerate or decelerate3 F) l: O6 T; l6 j' Q' Z* b7 G# T! |
  phase                    ;; keeps track of the phase0 ^7 i0 K) E- A/ X
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 L7 [3 F) I3 \; W( q: c9 K  current-light            ;; the currently selected light0 ]7 S& l" T9 M/ D0 P5 r7 R% d& v

0 I9 S! `4 Q$ v9 X% x+ o  ;; patch agentsets+ i; c/ t0 I9 K6 h
  intersections ;; agentset containing the patches that are intersections
. V3 {% @( i/ O+ \2 Q% L6 w+ ~  roads         ;; agentset containing the patches that are roads
- z, ?! t( ~) N. s1 T]
/ x& M# k6 h" I
* P9 i/ s, f. Uturtles-own8 f1 N2 c% M" H5 \: D, j0 Y4 i: ]
[
6 r% A' W+ F7 c- Q9 h  speed     ;; the speed of the turtle
6 ?- ?' Q' g, i  Z/ A( k  H5 p  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# Q( K6 s4 ~( ~1 J1 g: l8 O. s3 h
  wait-time ;; the amount of time since the last time a turtle has moved  C3 G! J  h4 e5 j& a# g( B
]
6 e% `7 `' Z* P& a( G* K5 _: x( d
patches-own+ b1 z0 _& p, V0 a& N
[' Z% x) x0 ]5 t$ o* X
  intersection?   ;; true if the patch is at the intersection of two roads" h5 y- Z# }! J3 R/ ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ E6 p- V8 T" f7 D3 j                  ;; false for a non-intersection patches.
" B; b/ E- p( N8 S% C  my-row          ;; the row of the intersection counting from the upper left corner of the8 Y; Q, {' ?( r" c8 \! _2 Z
                  ;; world.  -1 for non-intersection patches.  G% T% m+ b; j( d7 P
  my-column       ;; the column of the intersection counting from the upper left corner of the
  Y+ }0 b8 D6 E0 \7 @                  ;; world.  -1 for non-intersection patches.1 r  G0 n/ H. x; K% f/ k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 J5 ]. Z5 n* Y. @
  auto?           ;; whether or not this intersection will switch automatically.
# M% c$ F( i9 k- }8 j                  ;; false for non-intersection patches.
9 S7 g/ c8 }' Y3 X7 M7 f6 }]
6 @2 h6 ]' I' _/ R& b9 R/ w
# e1 I1 h: f. s" p/ p, r, e/ @+ a  `0 r# z$ [4 Q7 e3 W# A
;;;;;;;;;;;;;;;;;;;;;;
2 m: s1 l$ ^. x;; Setup Procedures ;;
( b) i( ~, V" I: j$ Q# m4 Z;;;;;;;;;;;;;;;;;;;;;;
" H$ l& S4 m( N
3 r' `2 S- G! F7 A3 W. r;; Initialize the display by giving the global and patch variables initial values." o" c$ j$ O6 m. R7 d: j* ^
;; Create num-cars of turtles if there are enough road patches for one turtle to4 l; d9 J. G; s3 x# B3 d1 K/ e
;; be created per road patch. Set up the plots.- ~; g* X2 G8 ?. e4 _
to setup; G8 [  H% {7 P; B8 c: F
  ca
- t( x1 `1 U0 t, M/ l  setup-globals
( s8 b4 F# O* R. l; o/ |- S8 j) v" G
  ;; First we ask the patches to draw themselves and set up a few variables
# _6 ]3 [* d/ N7 m/ W$ X  setup-patches% R# u3 F' F( m0 g
  make-current one-of intersections
  R( _/ w, M$ [/ F  label-current
+ \( s$ T. L' p* a$ s0 g6 \1 t% U
  set-default-shape turtles "car"$ m. E  r$ _! _. s) i" N
9 w- h4 x2 o) n: V
  if (num-cars > count roads)( Y/ C/ p  E: Y
  [
, U) E5 b' R3 J8 h    user-message (word "There are too many cars for the amount of "
2 O  Y/ I5 B+ E0 x8 Z0 u: z5 O                       "road.  Either increase the amount of roads "- C$ ~0 z4 }9 X7 s' ?3 S
                       "by increasing the GRID-SIZE-X or "2 v" h) f- m% j; }$ y; r4 H
                       "GRID-SIZE-Y sliders, or decrease the "
5 W4 @7 K; f8 m4 V; K                       "number of cars by lowering the NUMBER slider.\n"
& ?+ l- k$ C# m: _                       "The setup has stopped.")1 U8 X1 v+ S6 W1 C8 W
    stop
0 t2 _; L# H  T: J  ]% Z6 v4 N- R2 T! i8 y) }+ Y
3 K! S0 {7 j5 W9 M) W
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 R$ L: Z9 w; `' q0 A  crt num-cars- W" C$ p2 {( z  t* M6 j% X
  [3 a" e# B+ z: L: S$ ~& E& J
    setup-cars
3 }' J2 h, `. k7 M( W: u& V. i) N6 q    set-car-color. D; Q& k1 c# d/ M0 e9 C
    record-data9 o  ~: m' i0 _' i- e* T1 @' l9 c
  ]; `  j8 M/ m3 ~8 G6 X5 M
$ H$ F' f' ~# `
  ;; give the turtles an initial speed1 J4 B+ j6 h/ `( O1 x+ X8 t
  ask turtles [ set-car-speed ]
. l: I: v4 m  J) W# T" l
4 t' h: Y3 F4 j  reset-ticks
' k7 ~6 u* m3 K: Z  K' Qend/ P% u$ v# T- {

, Q9 s& o' b7 B% L0 g;; Initialize the global variables to appropriate values
9 c6 S9 \* E. r6 d4 H0 Kto setup-globals8 W* O8 y1 t# s3 |: e
  set current-light nobody ;; just for now, since there are no lights yet* e2 o& K8 |7 ]1 h6 a
  set phase 0
: E- b) f1 a( M$ c, m  set num-cars-stopped 0- t  Z& c8 p7 p" x! [
  set grid-x-inc world-width / grid-size-x
2 w$ W- H3 j/ }! R; q9 j3 S  set grid-y-inc world-height / grid-size-y
) P* T9 d1 T) @: P* X* u* @% P' ]  v$ _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) t* q3 G* S# i, M4 B  set acceleration 0.099
* t0 I; x) N/ H8 Q, X" d/ Aend1 I6 b! q! R6 ]- c2 Y2 a# S  P& [5 B

: K: M& h: ~6 s  G8 H2 d9 {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) t3 i% g' x2 d' v1 e  A2 W: l;; and initialize the traffic lights to one setting
7 w. Z- r  N- N$ fto setup-patches
+ k; r3 k: f: ]; K1 f) j' ^  ;; initialize the patch-owned variables and color the patches to a base-color9 X" V& _! Y, T  Y
  ask patches& h; R3 n. l& F) w) S
  [
0 P: D# L6 D6 }& O$ P. ?4 M    set intersection? false' \4 v) t" W# u2 u; b* d7 @- S  N
    set auto? false  y+ F3 U! b& W; V* `: P* N5 t; f: }
    set green-light-up? true- O/ @3 v% y) @" b
    set my-row -1
( y# Y' o) b4 o+ R. K    set my-column -1
& i; D5 B! u' t! i* p& N; W* C! D    set my-phase -1" q) O3 Z& Q2 c; o: r
    set pcolor brown + 3. ^, h1 E1 N' m% X* p4 A
  ]
8 @  Y+ s$ f  _; \  B  q* {2 T: E# o9 S
  ;; initialize the global variables that hold patch agentsets
' e5 @# d2 N. G" }' m6 T  set roads patches with' ?; h$ Z4 f+ ~7 g9 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 K/ x3 v1 t  j" M" h    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# c" @* b  u6 k7 U4 {: j, O
  set intersections roads with4 G" S3 F8 x: H9 a# }+ I% F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! `! c) @2 g- I  c% B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 Z6 V9 m3 J6 P) j/ h
5 D( Y4 S; ]; C5 S) j$ p# ?) `  ask roads [ set pcolor white ]0 Q' P: a* }# j! P- Y
    setup-intersections1 ~5 j8 H3 ?( N( d7 r+ e6 E, f
end8 ]2 Y0 o% ^, N* P' n* s0 [
其中定义道路的句子,如下所示,是什么意思啊?
0 W3 I/ j5 V. I; L3 e+ V set roads patches with
' Z3 O1 J8 M3 ^) B; B  g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- ^# {1 e. v) h6 |4 |7 e% n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- t! Z6 `4 p" d8 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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