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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。
' k- _2 x9 M* ?3 j2 H$ n1 o: }netlogo自带的social science--traffic grid这一例子当中,
! b: G0 d# {* `0 k) vglobals! ]3 h3 N  Q0 J* e/ C9 M" v9 T- v
[
4 M$ ?& O" U2 W' ~$ x  grid-x-inc               ;; the amount of patches in between two roads in the x direction
, G3 }' }" U( c( _  grid-y-inc               ;; the amount of patches in between two roads in the y direction& I: s- w, Z+ j8 X2 j* p
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 h; g- n3 }1 r1 I% t" w2 a+ R
                           ;; it is to accelerate or decelerate
& r' V5 S) a" q3 b. B! e  phase                    ;; keeps track of the phase
$ }5 r' Y6 K; ]# D0 [- q$ B4 `# N  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# s# ^5 n) ]0 x: B2 \$ h3 y/ |
  current-light            ;; the currently selected light
0 _# w, [% L9 L' B  n8 R$ f4 D3 G. @5 a$ {' A( K+ Q
  ;; patch agentsets4 D7 O7 d" S! p, E& K; I
  intersections ;; agentset containing the patches that are intersections9 |) T2 a4 _1 n* X( C8 ~0 O* ~; n/ L
  roads         ;; agentset containing the patches that are roads
3 n! `5 L% I1 u9 Y* Y& a3 u]
5 s- Z3 m7 \3 u* \  H& r# G  R/ L# ^) X9 g2 s
turtles-own( ?! C7 X7 f# _- A6 U. T/ G
[
4 X& ~' q' P6 m( r; |- ?  speed     ;; the speed of the turtle, M- ?; B! W4 h4 I) e' `/ f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 H0 ?  f6 m/ D2 Y2 k7 |) U5 g
  wait-time ;; the amount of time since the last time a turtle has moved
2 L7 O5 p6 b2 k6 n]
, ~6 J0 X+ _/ {) p+ \# X0 t
$ T, S& C/ ^! epatches-own
; |' s# ]3 M# x$ N: m[
% d; ]% W5 Y' u7 ~  intersection?   ;; true if the patch is at the intersection of two roads* Y* q$ f" m% ^: J9 A
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.6 O- g6 O3 Z. h- ?6 `
                  ;; false for a non-intersection patches.
; C% N: S/ t" y& R$ e; h  my-row          ;; the row of the intersection counting from the upper left corner of the
# z7 i" v/ k% c* l                  ;; world.  -1 for non-intersection patches.
% V# `# m' @3 E  my-column       ;; the column of the intersection counting from the upper left corner of the) C, S9 V) E3 R$ m5 _
                  ;; world.  -1 for non-intersection patches.
6 d/ q* p4 z$ t4 ~, v; X: I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.9 M" {6 x' _+ r6 ?
  auto?           ;; whether or not this intersection will switch automatically.( \# B' T* R. v) `5 t
                  ;; false for non-intersection patches.
+ O9 S7 i+ ?1 p+ x. V]" C  ~# q6 w+ a. k  I
; N2 k* O/ R& B6 ]$ E% P( M) h
& K( N. `& P# N: i+ t" v% ~1 W4 {
;;;;;;;;;;;;;;;;;;;;;;/ q6 W, P8 ~. ]( U2 K- ~
;; Setup Procedures ;;
& W5 n& ~, T* K  X3 |, l;;;;;;;;;;;;;;;;;;;;;;
: a! L# E6 R7 _5 \0 _, d
* e% ?3 ?  e/ K5 v;; Initialize the display by giving the global and patch variables initial values.
4 M9 a% [$ K+ R& b3 D;; Create num-cars of turtles if there are enough road patches for one turtle to1 E& U/ I  M. C" P  G
;; be created per road patch. Set up the plots.
. J& V3 g" z" m! H# {to setup  B7 P0 C. x  g" n' ]5 n
  ca
( I. ]3 _9 }  l' M  setup-globals
2 `' r' I) ^) P. q4 S
; P" {, J* r/ A  ;; First we ask the patches to draw themselves and set up a few variables
5 y* \0 l2 Z) U, |4 R  setup-patches$ L. Z, v3 d8 }
  make-current one-of intersections
. i) J( Y6 b5 ?8 K; ^- g% P  label-current) T: E, A5 x: k# B0 v

1 S: [% M: p0 H$ \  set-default-shape turtles "car"
. [1 G7 i- Z1 D- U+ R/ `, \0 G" u" M) |1 p1 b3 H& B% v: |
  if (num-cars > count roads)) T$ |, Z# V) `
  [2 g' p* }2 f+ _. y
    user-message (word "There are too many cars for the amount of "3 X. d" g& K( L
                       "road.  Either increase the amount of roads "
0 a% Y! \. [. p  @) H                       "by increasing the GRID-SIZE-X or "; W# D# {; `! S7 v8 u0 Y
                       "GRID-SIZE-Y sliders, or decrease the "
" f5 A( q% D& [( b9 _                       "number of cars by lowering the NUMBER slider.\n"( K! Q. F1 D' G2 k2 R
                       "The setup has stopped.")# t0 K8 e  `: z+ v+ U
    stop
- _( {; o: {1 l9 u' w0 l  ]  f/ \1 X5 j; y8 P" O5 M
) ^# \: r4 t" m5 F  o. o0 f5 D
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ m  p: ~7 c* l7 P  crt num-cars
: l) p* `0 v+ h  v" X( O  [. a" |$ s: l' V* x: s/ g1 u. s' a
    setup-cars# ^( A# O  u3 n; J
    set-car-color
" D- F% a1 o$ d/ ?. h/ A" G) k, ?    record-data
3 ^% g, T" ~* g* |" }7 D1 B  ]
, F5 @" R4 @: P2 n2 W( K! N& L$ h" P  [% q( b9 a+ l. B# `$ [& ^' O. F- b
  ;; give the turtles an initial speed- Q5 [+ `' U# v$ ]7 \
  ask turtles [ set-car-speed ]
  D) O+ N" S3 O1 N( z+ y7 V( c
# ~# H- M3 Q2 \  reset-ticks
$ A, o5 H0 ^+ J! Q: N; p1 M/ k0 Y- E/ rend
0 m6 g) \: Y* `1 r- j5 }. f8 E5 R1 ^5 c1 @
;; Initialize the global variables to appropriate values
3 `! q, W  i9 g4 f% r8 G- R8 p0 V& rto setup-globals8 \) v" ~* ^3 k1 [* ~
  set current-light nobody ;; just for now, since there are no lights yet
1 E0 [1 r& @) r( u0 c$ Q  set phase 06 j; k  v$ ^# X$ o5 {5 K2 l4 \1 O5 l# ~
  set num-cars-stopped 0
+ b8 b3 m6 [  V( `! Q- Q  set grid-x-inc world-width / grid-size-x8 g- u, D: x: Q1 f7 t
  set grid-y-inc world-height / grid-size-y
' H. E$ L: B1 E; F9 e! ?. I8 O- C, h  e' c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 a/ n/ Q4 i- b4 x% X  set acceleration 0.099! x: @. f( J5 m  W% C/ w2 n3 L- |1 _
end( F4 u! \8 }+ N" Z/ D0 O
8 [! N( C, q8 c7 m
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  a/ Y7 ^6 G6 \4 I  H1 Z;; and initialize the traffic lights to one setting
  G) L8 |) Z1 M' fto setup-patches
4 _0 o8 s: ^, _$ `( [9 y  ;; initialize the patch-owned variables and color the patches to a base-color4 U8 ?4 V* J" i+ }( e
  ask patches5 Z: B, N: H4 P" W. u% d# K
  [
: M+ B. D( ~$ I( d# e6 b    set intersection? false
9 d' g0 L0 d. P5 U, J' ?* ~+ C    set auto? false
8 L2 H) j9 \) T    set green-light-up? true6 y, p. w- C0 y1 t# |
    set my-row -10 V; c# w: c' i9 y* c6 v
    set my-column -1% i) `/ r1 Z4 H
    set my-phase -15 B8 n; ^: O+ y# X3 E8 T4 l2 _. f
    set pcolor brown + 3# K" v  y: R, V! d
  ]
! Q, T$ e3 Y# Y8 ~0 M" A8 s
1 |, |9 t2 l' \  ;; initialize the global variables that hold patch agentsets
$ i6 K6 u3 S, k  set roads patches with
( ^9 f, d( z8 J, u6 r, M3 Y& ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; N' j4 T& h; @. p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# O7 K3 k4 I5 @1 r
  set intersections roads with
' K9 Z5 s5 R! W: m5 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and7 z# E' Y: y$ n6 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- F, k3 a* r, Q1 W
6 Q2 r' F+ g: A1 n# W. w$ R" @9 w  ask roads [ set pcolor white ]& v% |' e- `+ F) K& d3 @& Y% y
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?* w8 U6 N7 y: F* h/ d
set roads patches with
) e' L, L) N, v1 n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 S; H% F- ^2 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 U$ f3 e. n( }
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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