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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 i" I( T+ P& [6 L8 @) _( lnetlogo自带的social science--traffic grid这一例子当中,+ q) o7 r& B1 {& n# _7 X  W" `
globals4 x6 X4 w, L. d% x" x& V3 N, n" X
[5 O& Y- P" |8 ^+ \: f4 k- L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ o# c. l( a0 {: P7 w8 i  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 a7 n* ~, Q! I8 _1 l
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 l) Q8 Z( d* ]- G& ^% u, z+ Q% N$ V                           ;; it is to accelerate or decelerate
2 H% _' a9 o* d" b  phase                    ;; keeps track of the phase( d. q/ o/ Z  _' E# u+ z1 C
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# J" i1 V2 {2 R1 {* O6 L
  current-light            ;; the currently selected light
8 Q% B5 w! D; H- f% u# q4 K
9 o- {7 I$ [' ^' @! Z$ L: r  ;; patch agentsets. T: j; d0 `8 `. l' x. H- U
  intersections ;; agentset containing the patches that are intersections, k2 k! Z, ?) d; e$ E0 e8 [
  roads         ;; agentset containing the patches that are roads
# a3 y$ C: o6 n]5 r$ F# e! {6 q+ V) x
. L2 Q# ~; }9 h& J! [: K
turtles-own
/ q) T: X; Y9 G! O" M+ w) B[. R/ B  {) H9 f( j* e
  speed     ;; the speed of the turtle0 J! f6 L7 H' x' ?- h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  k# b* Q" Y, e: F  wait-time ;; the amount of time since the last time a turtle has moved
! D& \/ B, L- f  y. \5 @]4 c  D8 N# \' \9 j8 i9 ^7 H- |  Y

$ i( q' [8 t1 Hpatches-own* k  ]6 _' [$ k3 E7 B! p
[
2 h* ^0 X" @8 W5 @  intersection?   ;; true if the patch is at the intersection of two roads
8 m; o& g/ X# d. L$ G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
' A3 T+ ]3 M! o$ u+ Z" C6 H8 g' O                  ;; false for a non-intersection patches.
; {9 @! h( z8 `  my-row          ;; the row of the intersection counting from the upper left corner of the
2 s8 D" Z# A0 `" a4 e. c5 a                  ;; world.  -1 for non-intersection patches.
0 W2 Z$ |3 D4 T% D% N  my-column       ;; the column of the intersection counting from the upper left corner of the! H# c0 O& O/ P0 w
                  ;; world.  -1 for non-intersection patches.+ m3 N9 G2 G* S8 n- v1 H+ I# J1 E
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  e/ _: E0 ^  ~1 T, Q. }6 o
  auto?           ;; whether or not this intersection will switch automatically.5 b' ]( s8 C6 e; M
                  ;; false for non-intersection patches.
, W5 L  }* e5 j7 e]
6 [8 r1 P+ p1 a
; @  \2 A, _& v& ~; ]: X4 x
( Z' L1 f4 ?" T, K, C7 h;;;;;;;;;;;;;;;;;;;;;;0 B" u1 B# N2 K1 a3 X3 N
;; Setup Procedures ;;7 K! |. X& a5 ~1 U8 S' s- Q% a
;;;;;;;;;;;;;;;;;;;;;;
1 |: m8 ]7 D6 k& V9 b
7 [! r  s* _  s' V/ [;; Initialize the display by giving the global and patch variables initial values.) u+ m9 e: D8 F3 J' {
;; Create num-cars of turtles if there are enough road patches for one turtle to" {/ b2 @7 H9 U; F: [, n' z
;; be created per road patch. Set up the plots.
: S# i# ~4 w! o3 hto setup
2 H3 r" P2 U! T" }; w) m% g% i# e) a  ca" n+ W+ `) B! l- j6 x! a$ f! ~' u2 n
  setup-globals
5 `+ R$ b# g! }$ b; A/ b; D% G/ i/ L9 H# `# G0 v9 Z
  ;; First we ask the patches to draw themselves and set up a few variables2 t: }0 i. S9 Q; Y- B6 ~5 Y3 m
  setup-patches
* ^) N8 h6 w  f  make-current one-of intersections! e. o! W! r5 k: J# E5 ^" I8 _3 _
  label-current& p! U, @* p" t! B3 C" o7 |
! l* D/ a% T" H0 [3 g6 ]
  set-default-shape turtles "car"
1 E7 _2 N+ P* Q# O( z6 v
! \3 t: |- M. w5 {1 L- H) X" U  if (num-cars > count roads)) |- d  e  [: I
  [
1 H; G3 Z- [5 z- u9 `1 t5 y  ]    user-message (word "There are too many cars for the amount of ": n# u  E! b7 c. h
                       "road.  Either increase the amount of roads "
6 `/ S" I! F" f1 @6 `8 g                       "by increasing the GRID-SIZE-X or ", k% _& ~( F8 d; H$ T+ K
                       "GRID-SIZE-Y sliders, or decrease the "0 ?; e- n5 w! ~) [; M! c) C
                       "number of cars by lowering the NUMBER slider.\n"
1 K6 z- S+ H; z( l                       "The setup has stopped.")
4 T: m: n( s' V% K+ a+ C3 _2 d    stop1 r0 H0 x, x! r
  ]& h2 v; R$ T( G/ p
6 x4 f5 r- N0 M" i1 m  c0 \, P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ ~! }- e1 p, V" M! |: P# \  crt num-cars  X" w2 T, i, M& f2 u
  [. I' f1 m' p. E
    setup-cars$ l7 S. x. [/ |
    set-car-color* F' F* d3 ?" v
    record-data
, s* k; R  }$ |1 y$ x% t  ]/ v9 H- b! s) j& e# }: [
7 ?" @) K1 G; V8 V, M, P
  ;; give the turtles an initial speed
! Q5 u! Z' a, S4 J' I" k. ]* N  ask turtles [ set-car-speed ]
5 `( k2 I  A. z
' ^% l$ B* B1 _9 T( ]! e/ ]* t* a  reset-ticks8 @8 J8 A: ~& n/ K4 |  y
end
% @+ T) E0 [  [% B  y
8 r' `: M5 t5 H7 ~0 D$ p6 f;; Initialize the global variables to appropriate values% ~5 G$ @% ^7 _( V# S
to setup-globals
0 \- n& T% B* Q" |. m/ R  set current-light nobody ;; just for now, since there are no lights yet: w- P7 G/ M& h0 a. a$ M
  set phase 0, S1 E; o/ b1 P0 F: g" T$ U. W7 \
  set num-cars-stopped 0
  h" M! L2 D4 E0 o. I5 f: d  set grid-x-inc world-width / grid-size-x
; ?) b9 R  S2 H6 g  set grid-y-inc world-height / grid-size-y3 X  T9 i. V. I, m% x( F* m" L
. u& Q! l5 D- r" N0 J* P" [6 b
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: I$ A* Q" s. B3 I. n% ^- a$ }  set acceleration 0.0993 |8 i6 @9 T; i5 z
end$ j: t7 `8 W$ M$ c7 i
0 [  G" E* J' N" T; t0 X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 j1 Y0 b" `$ K* A
;; and initialize the traffic lights to one setting: d% D9 x. i' \! @2 }. i
to setup-patches" |" m, Q1 k5 Q$ P( |, \
  ;; initialize the patch-owned variables and color the patches to a base-color0 ~/ Q% o8 ?6 X9 K+ O" J2 O  `
  ask patches3 w# P! f/ e/ x- Y1 b1 m
  [% V( W  ]% H; d+ O6 I1 I, _; g
    set intersection? false) C3 b/ O9 R0 ^% c' h; X# o
    set auto? false
( S3 `/ d; _8 n% C    set green-light-up? true& x) s8 [5 m8 A
    set my-row -1
& l; Z3 H2 a# E7 @# ~$ v% ]    set my-column -1
/ G5 E, l, {) j    set my-phase -1
% V( a+ l7 P! g- I% {: W# G* `0 i    set pcolor brown + 3
: H1 ]( r5 p& K9 B7 z) h  ]
  |, r. v, i  e* r) ~3 v
/ U( `4 R/ Q9 H4 q  ;; initialize the global variables that hold patch agentsets/ W; M3 \, N7 O9 k
  set roads patches with: `8 @5 H8 Z9 q7 V0 I6 I: u* p
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ @  V* ~4 F/ ]" W8 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" I/ \/ j( g  P5 p! G, ?
  set intersections roads with
3 N/ t1 _% H1 g7 x% f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; l3 N! @( \& {# D% `5 t* W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 y$ S3 V! f& y% v6 d. }6 b9 w1 o, D6 W! ]
  ask roads [ set pcolor white ]
" w# r4 [; M& Y! j% f- G5 d    setup-intersections
- v  y' Q/ t6 Tend& t) z. x" R" U: }/ B  s
其中定义道路的句子,如下所示,是什么意思啊?
: X- k; X5 {' j1 z set roads patches with8 \2 ]6 i, S* O0 x9 J0 K  w* v5 L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 e2 P) l; g0 z& b- U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ O! w& l: R. b. N# y
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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