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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。
: Q: U+ O% b0 {  p& inetlogo自带的social science--traffic grid这一例子当中,
  O" q# `  s: G  I9 pglobals
% f8 ?- I3 _3 b" a$ R[
$ O( p2 ?) N  N. U4 a5 x  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' L* X5 e" X( s* C  T% `* o- j/ g  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 x/ F% Z+ f, D. c6 `9 Q0 w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 C" i' S. j0 _                           ;; it is to accelerate or decelerate* Q) b8 Z. D: p& I) L
  phase                    ;; keeps track of the phase
$ r9 C" _4 F# ~9 z* y6 K  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& G; {. ?! U$ p  current-light            ;; the currently selected light7 y' j% Z! y+ V) O

7 |! a- {! w/ n9 t' \. z  ;; patch agentsets
' ~0 h6 n" c0 F+ C% K  intersections ;; agentset containing the patches that are intersections7 v6 M' P0 d8 j1 u- ]: n! H& O
  roads         ;; agentset containing the patches that are roads' B5 Y1 n+ _. K& i% ], J: b0 Y# F: W
]2 K1 N: j5 x* c8 d

, G  D4 D3 Q) ?* o3 }% F0 ~& l# Cturtles-own, o0 Z. j" n. Z4 n
[) O" _* _9 O% a% c$ K- K
  speed     ;; the speed of the turtle4 G8 j) m2 d0 k8 o
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right' A3 ?. H* d' V( S! z" D
  wait-time ;; the amount of time since the last time a turtle has moved, m% v: ?8 d4 D7 o
]
* Y9 w& I- A" M+ g1 `4 S1 ]' l4 A/ R) t2 y1 L
patches-own
6 a3 s! G/ z- D$ x) j0 I[
" s$ u/ r- z! a! n* _& F3 J  intersection?   ;; true if the patch is at the intersection of two roads
) ~" n3 k  H, m  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 s, Y: c7 m5 y% q4 b3 m# Z                  ;; false for a non-intersection patches.
& }& ~% X0 K. e/ h  my-row          ;; the row of the intersection counting from the upper left corner of the& y1 p) |# |5 g4 N# i3 ?  A  `
                  ;; world.  -1 for non-intersection patches.0 q2 L4 F: o9 n
  my-column       ;; the column of the intersection counting from the upper left corner of the
: J7 Y8 {- T4 `/ b6 d                  ;; world.  -1 for non-intersection patches.- r8 d; K. S+ x" ]/ p8 f' y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) e1 H5 V+ e$ V5 G( C
  auto?           ;; whether or not this intersection will switch automatically.
& l! N- A/ f  ]' b                  ;; false for non-intersection patches.( c8 ?6 H) \6 E2 R2 r  C
]5 z) R$ ^; F3 q0 x8 p$ ]. X

# W' q( Z0 s( X' v/ K$ }- g, n. C( @$ h1 ~) b$ Y" w. n
;;;;;;;;;;;;;;;;;;;;;;
- W6 ?, H1 t2 y;; Setup Procedures ;;
, e( O6 o& |3 W2 A;;;;;;;;;;;;;;;;;;;;;;
1 n$ F9 v9 x4 _4 X9 [( F) R8 r7 l2 X  @& [  t5 i4 h) P
;; Initialize the display by giving the global and patch variables initial values.
$ R* a: N8 `* i) r, ]% v;; Create num-cars of turtles if there are enough road patches for one turtle to2 b/ [" A5 Y2 Z; p2 i
;; be created per road patch. Set up the plots.4 O" f: y# _1 D, z: r" U+ R  A; {
to setup% e% t0 F/ y; u
  ca
9 L* Z" h; P8 x7 s! G8 t  setup-globals& I/ \! m/ X9 C- \* g" l

. p( w2 H3 R0 p- q6 d9 w  ;; First we ask the patches to draw themselves and set up a few variables
1 o1 O2 j0 [! Q  setup-patches
5 S9 D* Z4 R# j- J- D$ B# q  make-current one-of intersections& G2 X. l  U$ z3 ?$ k2 n
  label-current$ t1 V, W- M: d! p4 r
: ]' g* {* j- e/ B& \! {) M
  set-default-shape turtles "car"
9 b, r" T" s/ w$ r7 E- ]' ~  E: p6 G4 m/ q$ G, H
  if (num-cars > count roads)
( J8 a$ v3 C1 q0 G( `  [
! h4 D% u3 y4 I( J8 X% O6 [  N    user-message (word "There are too many cars for the amount of "4 ?0 D9 X( p3 Z- |( Q" f4 H
                       "road.  Either increase the amount of roads "3 M) W* h% t9 t( \! h2 j0 I
                       "by increasing the GRID-SIZE-X or "
0 D1 N9 `& A7 f9 V! i# r                       "GRID-SIZE-Y sliders, or decrease the ") C, a7 A* R' V
                       "number of cars by lowering the NUMBER slider.\n"2 [4 {* O% m( m' u+ b$ _. x
                       "The setup has stopped.")/ w$ `: m3 k0 z: U$ r% ^. Q
    stop
/ \* y4 P# [9 ^) u) i  ]
5 \3 s+ E5 p: E! ?# A5 |: q2 h! O. u( r9 I9 X: S2 b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 _5 S" b/ V' h7 v
  crt num-cars
7 z+ y8 F. L; Z' o  [
7 g, i% G! j7 d) h    setup-cars
/ |# H6 X- D1 y( E; y4 P  J# y    set-car-color3 p$ R" [3 N& b
    record-data5 G" P" E+ B! j: J$ z" ?2 l# E
  ]
" I. R" p% ]* ^: H. i! h- s- M: z# i: W0 y
  ;; give the turtles an initial speed
$ R: P& b9 S9 \! j3 I0 l  ask turtles [ set-car-speed ], f, n$ m, l8 H8 k
" K9 h7 i. r! l/ Z5 c+ [
  reset-ticks
" ]/ [0 _" |; g1 mend8 v3 a; o* c) ~! U0 X! N0 \2 j

1 t1 [! S, m1 C  Z5 \7 v. s+ x;; Initialize the global variables to appropriate values
# V# y& {- j) g) v9 l0 V% Lto setup-globals- F# v* f+ r, x* i+ K1 z
  set current-light nobody ;; just for now, since there are no lights yet
% h6 G% b- z. D* L  set phase 08 J: H* h6 h/ o& R$ G, L4 M1 {
  set num-cars-stopped 07 I6 R) w! i3 Q
  set grid-x-inc world-width / grid-size-x$ Y' W$ O6 k  ^# q8 z
  set grid-y-inc world-height / grid-size-y! F/ M) Q/ o" }& a+ N9 F) s" v( Y

& C) D# ^1 a! W# |! K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
( \0 z& O5 Z: F9 t- D8 T  set acceleration 0.099+ l: B2 y+ \9 L1 i+ J) y& L; M
end
3 Z6 k( c) e' `4 r3 K) f3 ]* {, k. ?: A, f7 L3 ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' R2 {9 x  C% T;; and initialize the traffic lights to one setting
# ^& X% q' f5 R( Q2 p8 pto setup-patches2 E0 r* V# I8 H  i! `6 H
  ;; initialize the patch-owned variables and color the patches to a base-color
% x% @& ^- x1 g  ask patches
1 D( S' r# T# K7 x. j3 d# M  [
# e, Z( ]- c0 ?8 U: r    set intersection? false
$ a) |& |: t3 A( a7 k- r: I    set auto? false, A" J+ |' y9 N
    set green-light-up? true
7 x, E9 ?( t$ V- R1 s, i3 Q) I4 Y    set my-row -14 t! Y4 f6 D$ N
    set my-column -19 _2 ]4 f/ a; L: {
    set my-phase -1. X1 E5 j$ K1 m* p/ i9 t5 d+ g
    set pcolor brown + 3
  G% k& D9 e0 k0 m2 U  ]% N% F* e  Q1 d* I' J
$ g! \6 z0 z" ]% N# T+ i
  ;; initialize the global variables that hold patch agentsets
( {0 p) h- Y) c$ C9 X5 J  set roads patches with8 K7 n* d8 v  B+ E3 |. `: F! a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* r8 v4 I2 e2 z' R/ A1 E& M% f6 Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 Q& N9 |2 Z& K6 J( I. n
  set intersections roads with: c# h: G- }3 c& A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and" a! `( ]9 c: m3 C1 ^2 w. D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  ?$ k6 Y4 D  t% j. O0 |4 z! Q/ V! H- s
  ask roads [ set pcolor white ]
, \5 Q* g4 z* x% x" A* J    setup-intersections
) n+ [  S& @# E0 z3 A/ yend1 a# v* N# C# ]8 \9 k' M' @
其中定义道路的句子,如下所示,是什么意思啊?
/ F* c, w8 `1 j* B* r: j set roads patches with
. _4 _* A( `4 M  o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 r$ O  y1 x' e0 t- @9 z, M/ Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. e/ ?4 g' \' ^
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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