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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。9 g, f( O/ i( D* A2 p
netlogo自带的social science--traffic grid这一例子当中,; Z0 w$ Y, p. A2 z( y* j, |
globals
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, L! q# a' ^  o9 p- V! J8 I  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 e) w1 T+ ?+ A8 T
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  }8 M7 b7 n/ I' U+ v  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 @* @- j8 y5 m7 K& W1 e
                           ;; it is to accelerate or decelerate; Z0 E# H9 v8 K  A4 s- P; w$ L" ?
  phase                    ;; keeps track of the phase
% w- q( K% O4 k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. y: F4 S8 L$ l1 {
  current-light            ;; the currently selected light. w: K! W% [& Y6 f$ _
3 H6 z* M  H4 c) s* }: J
  ;; patch agentsets
5 g" p! n# C2 A# ]5 {) x# J  intersections ;; agentset containing the patches that are intersections
% Z) Q+ R. I. Q% e  roads         ;; agentset containing the patches that are roads
% F& B6 z3 P. b. b3 i! |/ C0 B  R]
" j% @' u+ }. ]3 b' u! f2 T9 x
; \% N% p, r$ C8 O7 L! R2 hturtles-own' f; C6 `+ ]; S6 _2 y7 V' ^, v7 V
[. w) D6 u, ]( d$ l& U" x
  speed     ;; the speed of the turtle
6 o& C7 s4 k  W9 a- m( s/ w  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( u# `. Y5 E/ ~
  wait-time ;; the amount of time since the last time a turtle has moved
9 d% }3 M+ b( v6 Z6 t) |( _* `]
2 W5 A! p' o; f: ~8 x+ O
+ z8 J% ^! t/ X; o; I) w6 Zpatches-own
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0 c! U$ k4 _! r4 }. U1 ?  intersection?   ;; true if the patch is at the intersection of two roads
7 E3 {& G* Y7 Z& ^% Z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! }2 \6 n& y2 g  X& D                  ;; false for a non-intersection patches.
8 Z- R( J6 u  D  my-row          ;; the row of the intersection counting from the upper left corner of the
' p& A% q0 e* b                  ;; world.  -1 for non-intersection patches.3 ~* Q" o* i4 _
  my-column       ;; the column of the intersection counting from the upper left corner of the
3 v$ I2 d( q2 Y* ?) X2 _                  ;; world.  -1 for non-intersection patches.
+ K, P! a5 q; S3 u+ X5 Y  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 R) y, Y% {3 S1 B2 ]  Z
  auto?           ;; whether or not this intersection will switch automatically." H7 C! F) Y" N3 D2 \0 N
                  ;; false for non-intersection patches.
: }1 L* Z# Z& o]
" o" W* _; L) M$ F$ E) n1 {4 K8 U; {( Y9 o

% c% x1 x7 q; ~; ?& q;;;;;;;;;;;;;;;;;;;;;;
6 r% A6 c, v9 i  j;; Setup Procedures ;;* y3 ?6 K9 z, W) I8 \$ C, M
;;;;;;;;;;;;;;;;;;;;;;
* r/ o  F4 e& c  {. [- q1 |; v- c/ _" h8 C! _0 ^3 h
;; Initialize the display by giving the global and patch variables initial values.4 y5 c6 |& l% w' p
;; Create num-cars of turtles if there are enough road patches for one turtle to
, T; W3 J1 N3 A/ i& `  z8 `# U) ?;; be created per road patch. Set up the plots.+ [# h# `6 e, r% O0 j
to setup
) C' H3 G. M! O, G  ca6 \* \( t( P; [  g4 U. o/ P
  setup-globals
7 g3 o, @3 n( g* B- S8 e$ M5 S! m+ o8 _* l2 y$ L
  ;; First we ask the patches to draw themselves and set up a few variables% z' ~! E0 I7 O
  setup-patches
# [. s/ I1 r8 N! ?8 A( D; F; W7 |  make-current one-of intersections$ j: ?1 H" v/ k; h% p" v! T
  label-current9 H! v6 A( Q+ k2 Y& N' H
$ d" N( H5 }/ F& ?- D# f
  set-default-shape turtles "car"
( C% [5 t% v* C3 k7 I" A* X/ F; }3 A! v, b. B- |" E
  if (num-cars > count roads)
/ a( O$ `/ N4 y. f5 {  [
; d* h6 C& g& S0 Z9 \    user-message (word "There are too many cars for the amount of "4 y/ @& p6 o0 I% k5 N! ~. H2 g
                       "road.  Either increase the amount of roads "
8 B: t/ Z7 O+ |/ W                       "by increasing the GRID-SIZE-X or "
1 Z  W; E" }, a                       "GRID-SIZE-Y sliders, or decrease the "
" c; T: C) |6 q                       "number of cars by lowering the NUMBER slider.\n", h; b/ |+ x% E5 ?% e
                       "The setup has stopped.")
' Y; C* \) x+ ^' g    stop/ I: ], Q/ C( |) Z" I
  ]: E, d7 [1 k8 _% i( ?
* y" U# }, ~4 R; \/ t
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  P% m) D( o" ?4 z0 l9 {' e  crt num-cars" ^$ x0 L" r5 I: M
  [
6 x, j* B! b* `+ t! w    setup-cars/ x, [: d+ o7 D2 n1 c7 m* A
    set-car-color
# @4 |0 J: h% L" z8 D    record-data
! v/ M* h+ v1 o9 o  ]# D; ^7 u5 E" R, q) p8 k0 S

5 b9 u2 ]4 e! f" H& T% e  ;; give the turtles an initial speed9 T7 S/ u9 \' p4 T- ]
  ask turtles [ set-car-speed ]
+ T2 W# g, f' S' u8 ]' Q6 _' u, b
7 o, t3 M. w7 r6 K( v; y  reset-ticks
- r! J( |& I) F0 H: U6 iend
+ K$ r3 P1 g# G* m& z! z8 {% [3 `
;; Initialize the global variables to appropriate values  P7 ~/ F% k3 q1 r6 X+ i  }
to setup-globals0 W+ R8 g6 y  C* U2 v
  set current-light nobody ;; just for now, since there are no lights yet
* n8 V6 I' ~5 i' S1 S/ z/ C  set phase 0
6 r  e  |& H& S" `) q$ m: [2 e  set num-cars-stopped 0
6 x' o# E4 t2 W, K5 S% j, Q  set grid-x-inc world-width / grid-size-x  j( j$ y+ g0 d6 e- `9 d* [
  set grid-y-inc world-height / grid-size-y0 {( m8 m, q# l" U/ }9 V1 p
" w7 C5 G0 ~. R8 O$ `- i
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! j6 o& ]9 f0 Z0 y! Y, C  set acceleration 0.099
4 y+ s3 L1 V* r* {* yend
  y! y1 y; @" f, U/ z% h7 e1 O* n+ K4 Q( j- @' E
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' p1 C- E* K( c;; and initialize the traffic lights to one setting
# b3 S7 @4 f$ H9 F& S' J( E) vto setup-patches0 Z: g. ^  d/ Z  C
  ;; initialize the patch-owned variables and color the patches to a base-color
' o- r1 k& Q1 ~8 g% W  ask patches
8 c( E6 e6 \2 O& R% A' T  [& `$ K" k7 H3 X
    set intersection? false
% K4 G1 p; X# A, q" \& p    set auto? false
7 V. s, d" r( K* F8 s: K6 T* Y    set green-light-up? true
! f7 f7 \# w+ F) C6 P4 r    set my-row -1. ~, `" C, n" q% b: Z5 k, L
    set my-column -1
2 f4 I6 s3 w6 ~3 |4 W    set my-phase -1
- r; t/ b$ Y) M$ r) D/ h) e    set pcolor brown + 3
' X' Z  @/ j; _; @0 z' F  ]6 V$ _% t: m+ F( A2 [

, j2 ?3 `1 \9 B# _  R  ;; initialize the global variables that hold patch agentsets
8 V- l& o* Z7 z  set roads patches with
( y5 l* i! N. d( k5 `! T' B, R# d" n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 B  y; z. [9 H4 v  c* m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 F* p0 U; c. B/ u+ y2 w9 D
  set intersections roads with& q( T' U4 f+ _- V( H* Z. P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! ~1 o8 d. g! [" }4 K5 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 ^, h# V6 @6 t" {
$ T- }0 o% [% k* }4 e  ask roads [ set pcolor white ]
' B$ {, ~: E+ o" M' k6 r, r+ b    setup-intersections2 m3 r: V& z3 P
end
' I7 B2 B5 O* N" r& }, y其中定义道路的句子,如下所示,是什么意思啊?0 J8 Q) o" W* p
set roads patches with% j. P' K  E% ]# {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" J: {4 t' a* o- Z* G( U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( i1 l  W: w/ T
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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