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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。6 ?1 @! M1 U. b
netlogo自带的social science--traffic grid这一例子当中,3 K  F: x0 ]& k0 _3 ]6 S. ]
globals4 l- {0 N: z5 i3 |- n, i+ ?
[& c+ f8 \' u" w/ d
  grid-x-inc               ;; the amount of patches in between two roads in the x direction: J) ~. L5 `* P3 u9 y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
3 L+ q0 Y( j* |. S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! ~0 h1 E! W' J' G
                           ;; it is to accelerate or decelerate9 C6 u$ x: S5 Q. ]
  phase                    ;; keeps track of the phase
! G7 K6 O3 D. M+ B* l/ |4 P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: Z6 ]  q0 ]  w% x% _2 ^& X  current-light            ;; the currently selected light
0 c+ r! h2 P  E& R; X: i* l. W& q1 j7 |; A9 b& G
  ;; patch agentsets, y& A: y+ n; Z2 D7 D
  intersections ;; agentset containing the patches that are intersections
7 y/ o) D  s. {# a  roads         ;; agentset containing the patches that are roads
3 O) q% y0 G+ h( s3 T]
$ G7 B" z) X7 C6 l' l* x' b6 n8 |5 a  Y
turtles-own0 K: H6 R' L" |; {  s
[
. V1 ^3 g" K, ]3 K2 ?  speed     ;; the speed of the turtle
) i! Q  h: i* _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 d& L: Z* w( O! F$ t  wait-time ;; the amount of time since the last time a turtle has moved5 ~2 n' o7 u  c; k# k
]
# X% [# J: A& U" I' P
2 A5 e5 y4 |) u: r, J) m' h% e9 m3 Ppatches-own
6 |1 v% }6 Y/ `& X7 o& c9 s: x$ G[9 v6 Q; Y+ c( S  P' a" b
  intersection?   ;; true if the patch is at the intersection of two roads# z/ W7 r- u; h9 T" E
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' R: d$ }1 z. j7 P7 D$ ]
                  ;; false for a non-intersection patches.
# A/ i( F& R4 Q" I, l/ S+ a$ I  my-row          ;; the row of the intersection counting from the upper left corner of the. J# o8 K; Y! R  D. H4 X+ E
                  ;; world.  -1 for non-intersection patches.7 i% ]% v: ~5 _1 T8 G
  my-column       ;; the column of the intersection counting from the upper left corner of the
& ]/ L0 S4 D1 ?% e# f7 ~                  ;; world.  -1 for non-intersection patches.
! n' q- U3 t* A8 S* ~  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  W/ _- B' O5 P7 |" G9 i  auto?           ;; whether or not this intersection will switch automatically.
# ?  K: C1 R) }4 Z8 Z( Z# O                  ;; false for non-intersection patches.
# P9 \1 A. ?5 q7 {]& }: w" C2 R' ^" n0 @5 W2 C
' ~+ k/ R, c9 x8 O/ Y9 h$ k' I- r

- E  v4 M5 f5 b" l) o7 R" k;;;;;;;;;;;;;;;;;;;;;;
: |% ~& D6 x, ^+ v, `+ K  D) Y' G;; Setup Procedures ;;
. P) h- y0 x3 G& w" L: H# R;;;;;;;;;;;;;;;;;;;;;;
; i0 ~# `' Z( I) v$ |+ R: v: Z& _$ w8 z6 x
;; Initialize the display by giving the global and patch variables initial values.
6 d0 I* V! d# u" Q) x;; Create num-cars of turtles if there are enough road patches for one turtle to
3 M( s0 i5 E$ @8 B& |" b. E6 e;; be created per road patch. Set up the plots.3 a2 `* f. i( {
to setup
: ^4 _' M& K0 z1 m  ca5 n* t7 \( O$ \: f/ U, V% H
  setup-globals
7 P# @. Y. ]- X# J
0 ~8 f9 K5 ?+ e  ;; First we ask the patches to draw themselves and set up a few variables
* p4 v$ r; n- m! Y6 H6 a) j  setup-patches* g: [0 W3 @7 S) p8 |6 F
  make-current one-of intersections
4 k, {3 _/ w, f- ?3 ^5 [  label-current) b  y/ R1 O% z; m
: I- }# a; @$ h5 u: {& q
  set-default-shape turtles "car"
2 T* }) ?$ M2 b8 O, b0 V, g
# {& O. {0 \1 W9 w  if (num-cars > count roads)
$ Q  ?0 @+ s' G4 }. p2 u  [4 X+ `3 u+ c/ y. W
    user-message (word "There are too many cars for the amount of "
  W8 R& O0 J* h1 P                       "road.  Either increase the amount of roads ": j& |( Z" n  s, w
                       "by increasing the GRID-SIZE-X or "
6 d* S. M& J8 v# t$ d                       "GRID-SIZE-Y sliders, or decrease the "
/ o4 c2 f: ^! _  r) g                       "number of cars by lowering the NUMBER slider.\n"
; Y- c( M$ z( ]! a# Q                       "The setup has stopped.")( p0 Z( ]$ j, H; Z
    stop
3 a# G9 e& h- M' j3 ^9 t  ]3 |) @* ^* p. O/ A" J% G( L3 ~+ j

9 L* @1 c6 E" D/ q. v+ L% g  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 k" a4 f" \' S: e
  crt num-cars  `: y$ M' `; r! B: m
  [3 f% A) {9 ?+ \. e" A/ v$ Z" }
    setup-cars
( ^+ L% E' Z/ l    set-car-color
. m" M, ^- G$ g7 _    record-data
$ k+ S' l5 c1 d  ]; c( E4 s: ~" L6 w0 z) H

- |+ u4 g) p. W2 k3 s  ;; give the turtles an initial speed0 Y- {% v' h- o0 P
  ask turtles [ set-car-speed ]
, j3 d  G7 a' x5 W" z
0 U9 ~( c+ A7 D: x, A: q  reset-ticks
6 Y# b+ x0 N0 ?end/ W" m/ J6 s) p1 O. f; B
( e2 c% s' b' ]3 `( r
;; Initialize the global variables to appropriate values
1 F7 a# d  D. p& [to setup-globals
1 F% }- K+ l+ d: L$ j' \( z  set current-light nobody ;; just for now, since there are no lights yet
& c2 n1 d6 E$ L  set phase 0
2 p2 ]( Y5 G2 {- Z  set num-cars-stopped 0
9 R2 ?" R1 N& f$ ?  set grid-x-inc world-width / grid-size-x
  R+ u3 ?9 a3 _  set grid-y-inc world-height / grid-size-y* x" t" P' @/ g# Q5 @

3 ^, S  ]- h3 k) _& L0 W  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# b' ^! F) a6 Z) a/ k% {  set acceleration 0.099
1 E. |1 c, T  l7 d" t% S  e. ^6 @end
# |: E1 m. e* w+ N& Y+ g4 J+ P" x) R: F! m, ]" D6 T
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' [( K1 L) T, z: ~, H;; and initialize the traffic lights to one setting
! @) `4 W! T. x) [; ^1 fto setup-patches8 h" @  P& R/ y6 w4 }' V4 w
  ;; initialize the patch-owned variables and color the patches to a base-color
2 P  N# S8 K% A' e3 u2 b" I9 F  ask patches1 H# ?: X  ^8 u" z) \  M$ w
  [' N! d( V% `$ ^1 T0 ~& H6 K* @, r
    set intersection? false
! e& B) O- F; J0 k+ k( P$ d% x    set auto? false* ~2 L$ X8 x4 ?( g4 s+ _
    set green-light-up? true5 t6 L! }0 s7 g; c' W# I' B
    set my-row -1
3 Z! u3 \4 V3 a$ [( z    set my-column -1* r0 q$ x( G) G" u, I. H2 s; E
    set my-phase -1
; b2 Z+ y& B; I! f    set pcolor brown + 39 `3 V1 a9 e8 s% ~* R, m
  ]
0 _* a4 ~7 g5 a6 `0 i6 I! s
; d( Y( Z  O* ~4 K/ I  ;; initialize the global variables that hold patch agentsets
( o9 Q! U! g0 y9 M# o0 _  set roads patches with2 J+ I4 h3 f5 X6 g: l+ V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 \5 H: d: x4 U$ Q; M4 X8 j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! ?+ e1 x5 ~0 r& X' Y  set intersections roads with
7 p  c( W4 y$ P" O" d6 A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. Z( C2 }7 Q& \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; A- v$ y# Z, H) O2 Y

2 L' b9 e) E# ^8 W! j9 u  ask roads [ set pcolor white ]
, }* h* [  y8 d3 k    setup-intersections. P0 E: j8 R4 k. e: v) r! S
end" a) j2 R0 G+ e
其中定义道路的句子,如下所示,是什么意思啊?/ G; y( q  j+ I/ e
set roads patches with
! ?3 r( x9 O% P9 M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ i3 o, Q8 E1 y+ |8 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, M8 q  K6 M+ p' e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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