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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。* \. M% G7 k' r
netlogo自带的social science--traffic grid这一例子当中,
, ^6 s& b% Y6 c0 R; Pglobals
  a# g( ^0 a4 J[# t7 P1 j7 w# G3 g* Y& D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; i7 W9 |& N0 I7 C. e( v  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: W4 h3 p; ]. d  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! j4 W8 T/ h) @; T! S% f5 u- l
                           ;; it is to accelerate or decelerate3 Q0 }( p/ v3 K; F; i
  phase                    ;; keeps track of the phase; }9 ^4 m8 z0 |2 m. y3 A6 D) A
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 B% P5 P% s7 j  k
  current-light            ;; the currently selected light2 k" }3 O; `0 Y$ V1 L: S

: @' C) n: t. U( N4 n, z( Y' Z  ;; patch agentsets( S5 R! z2 X1 J# T
  intersections ;; agentset containing the patches that are intersections
: L  i. g0 J% I! I6 k5 F4 @  roads         ;; agentset containing the patches that are roads; O4 y% U/ @5 i
]3 H6 T* t' K  d8 u' k
1 v& ^, D9 C& l9 o) e2 ?& t
turtles-own
8 r& T0 f6 s, z* b8 z[
# G, I: A6 C) S7 D: F+ \3 }" ^  speed     ;; the speed of the turtle
- d2 M' v1 S- i- I1 L; K9 h6 Z  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, E; ^( p: x2 I7 V  wait-time ;; the amount of time since the last time a turtle has moved: L" G' Q' Y/ u# i5 t$ Q0 O
]
; e! C& }! f) Y: _7 W- w! O: w  h+ G. [( L$ i% e* L
patches-own
) y) b1 P9 Z; [7 W$ E! Q6 b1 r[: _' _$ J5 \$ i  v# P; R
  intersection?   ;; true if the patch is at the intersection of two roads% @, e: E7 g$ `6 W* n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  w( J3 `9 x7 e" N1 ]7 B5 I+ f6 O" A                  ;; false for a non-intersection patches.! |7 r: `8 {/ B2 X5 Z
  my-row          ;; the row of the intersection counting from the upper left corner of the
! a- d- `7 P4 x                  ;; world.  -1 for non-intersection patches.
/ M2 t  q  j2 K; m# O. T0 U  my-column       ;; the column of the intersection counting from the upper left corner of the, \- d+ T- w6 O& C: @2 j
                  ;; world.  -1 for non-intersection patches.& h, P: D0 Q% ~/ w0 }8 |4 `
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( |' d( W* B5 I  auto?           ;; whether or not this intersection will switch automatically.
% Y  `7 k9 y$ ]# c                  ;; false for non-intersection patches.
7 n2 C0 l* M  E! K]
$ Y# S% j& o; p# B% |
. a8 L5 q% v9 M- X  D0 i6 k8 [3 N9 L1 z! x$ B5 i7 i
;;;;;;;;;;;;;;;;;;;;;;
0 }/ @- G7 n9 v;; Setup Procedures ;;
' ~9 |* Z% B) x8 k6 i;;;;;;;;;;;;;;;;;;;;;;9 S- C# y# A. D
% b8 `/ f' H! J% t- D* v
;; Initialize the display by giving the global and patch variables initial values.
1 s) k8 K* u0 m3 U, c;; Create num-cars of turtles if there are enough road patches for one turtle to7 }) k2 [2 P3 C6 N' K3 w  Y
;; be created per road patch. Set up the plots.
" ]5 b9 \7 X6 h2 h+ `to setup
# A' g9 h, ~# z+ O5 s  ca
5 }5 \% D- ]% w0 B  setup-globals
4 ?5 z6 K* Q! F& p0 \: f
1 }; z  m& s4 y, [$ t( o9 q5 E- P  ;; First we ask the patches to draw themselves and set up a few variables- E6 d0 X9 H' d% `+ D
  setup-patches9 _6 S8 ^# L: U. A2 u3 f
  make-current one-of intersections- I: d3 a+ b! B' H, v
  label-current
8 p, H; L* F- u" e( S: I* a" E; G% T) n0 p, C3 I0 r( f! Z; v
  set-default-shape turtles "car"6 t3 D+ Z' G: [4 i) @' I
) J4 D. ?4 \5 @
  if (num-cars > count roads)
: j" K& P/ K9 f' N  [
0 N4 a9 l7 X. @3 M5 e2 U2 l  x$ }- B/ M    user-message (word "There are too many cars for the amount of "
) x- H5 x% Z8 ?                       "road.  Either increase the amount of roads ") g' z! j6 h: i5 F* ]2 W% w! E/ p; ~
                       "by increasing the GRID-SIZE-X or "% F9 f7 G+ }1 x  o- z6 d
                       "GRID-SIZE-Y sliders, or decrease the "3 k2 W9 Q: P5 A4 j( e1 H! G
                       "number of cars by lowering the NUMBER slider.\n"
2 J! |6 ~  Y' ?. F% M. h$ D# X: o/ b                       "The setup has stopped.")) ]: j0 b% i' s! X8 J- R5 P
    stop
" p+ x9 s' b% W/ w. c3 X  ]6 ^4 l, }& F2 e: {9 w) A
3 O8 O8 ]) X) q) m, x
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" U* J( U* S/ `7 t) v4 F
  crt num-cars
* E& |7 B. R7 W3 H' i  [
: f9 u0 c; g, Y1 `    setup-cars* z7 l0 m0 \* g8 g$ p. m8 p. b
    set-car-color
7 c5 d6 O4 @1 u# c& p    record-data/ R3 m2 T2 S) W. D* Y
  ]/ ]( c( y. A) y; \

" Q1 Y' b7 o2 B1 x$ D  ;; give the turtles an initial speed
" m5 M, {, x/ a$ g4 V7 D  ask turtles [ set-car-speed ]8 T& j! W0 K' s2 {; }
1 L, b$ b' ]$ f! t
  reset-ticks3 l1 H/ X+ u, g
end
  P  t3 J* c  f# Q; _; }. Y
: ]4 x/ M! N4 N! h7 y;; Initialize the global variables to appropriate values
2 Q1 ?9 ^: l  I; w7 Eto setup-globals
7 f7 B7 d3 p. j/ X/ B+ \. R7 k  set current-light nobody ;; just for now, since there are no lights yet  C: x4 ]7 F5 z$ C; |6 h. r! Y' a
  set phase 0
8 g) w5 C& s% G8 x! `  set num-cars-stopped 0! F0 |: t2 j) b; _) h3 G
  set grid-x-inc world-width / grid-size-x
! f- a; [* c: H' ?; u  set grid-y-inc world-height / grid-size-y
9 E$ G9 C3 N; T  N7 u; Q0 g) u+ t/ N! L) l2 v# D( g1 ?/ N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ t- s% B! d8 ]; g6 y
  set acceleration 0.099
* z0 q, f9 s4 E" y" W' }, mend
) o( X3 Y0 `: {. b6 @& k0 _
. ~% S' |* L# l+ W$ a;; Make the patches have appropriate colors, set up the roads and intersections agentsets,! h' ~6 `% V) U8 X
;; and initialize the traffic lights to one setting% t6 k6 g& g& ~& D' R9 `0 M  D
to setup-patches
; u9 }4 \3 ]1 b9 F) p  d& l  ;; initialize the patch-owned variables and color the patches to a base-color( Q: G/ x7 |  e8 ^' }& v: r- H
  ask patches' l6 f4 y1 n# n$ [
  [
2 l/ D/ n6 X$ G' o: v& f    set intersection? false
7 N# \7 _+ ^, G& K% M    set auto? false, M, X" r1 \. Q7 x; u1 X
    set green-light-up? true2 W! p8 `) T0 ]8 b3 X& s, f
    set my-row -15 L$ ?3 M9 M. I9 E$ [! G( C8 n4 }
    set my-column -1
( \4 l" X/ d. ~6 x8 @- m    set my-phase -12 i/ a1 S/ [0 I) l- C2 V$ e
    set pcolor brown + 39 ^# D0 A3 C& G; Y1 g- {3 b3 ~" v
  ]6 _9 t: _; M0 Q
: g! O$ h' T! G& t
  ;; initialize the global variables that hold patch agentsets9 }( Z: K- z( R/ s* u' }
  set roads patches with" ?) R& Z2 x2 Z5 I
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; f6 \+ u- e0 x: l: i: i% U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 S% E3 V6 S8 b  p& y
  set intersections roads with8 f8 a4 u: l- g6 U9 W- [- p; |1 c0 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( r: o  O* f% l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! Q9 o; z" L3 O7 n) a+ d: ^0 `
8 R4 H1 v7 v5 r3 R* u) P  ask roads [ set pcolor white ]
8 e) k) I% a: L' R    setup-intersections, W' J% a2 i: k  E9 R
end/ u5 {2 v. Z  x7 `9 W
其中定义道路的句子,如下所示,是什么意思啊?
# s* c1 U' d6 Q" ?+ w8 x! j set roads patches with/ x5 U5 X3 e9 P" ]+ U& q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 q* G: {! x+ `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: p( b+ _3 u( v6 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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