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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。
+ W0 a* v$ b# Pnetlogo自带的social science--traffic grid这一例子当中,
$ a- Q) k5 D# U1 w# q3 D1 e( u5 Eglobals
2 G5 X/ \$ U$ v" I% y[! N- a6 P! f: x2 V5 Z. D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* J- B4 z& ?4 x9 C5 g0 }" {# i: l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction& j/ d6 V  a. E
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: k, |  ?3 t7 B                           ;; it is to accelerate or decelerate# ?1 p3 l6 M5 O) O/ |" G5 S9 F
  phase                    ;; keeps track of the phase
! Q- v& B  g; ?7 F7 [/ X  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 x5 K( _3 j6 |! e7 E" s3 h
  current-light            ;; the currently selected light# I; _( O" M5 c' \/ f/ @) A

% D; \; f8 C( c) O. f$ l' U  ;; patch agentsets
5 N# |7 i. G0 |7 P  intersections ;; agentset containing the patches that are intersections: R& I! P7 d( W$ U9 [1 |
  roads         ;; agentset containing the patches that are roads) G$ n. I: c* g) q/ M4 O; }% ]
]6 Q2 s" `0 G6 N" F* }! q' R
, f3 h/ q' ~7 n
turtles-own/ q/ o3 X9 J3 t! t
[
! K3 W- f+ \) T7 P( L4 G+ j8 o& K  speed     ;; the speed of the turtle, @9 |8 h0 g: j5 {$ h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 a' J' K  D& F7 f  wait-time ;; the amount of time since the last time a turtle has moved
$ b9 C6 `' s4 t6 u) U1 s$ H]9 T, C9 g% t7 n( x8 z
* w; L, t7 r3 Y8 ?# G4 c  S
patches-own  Q7 {' I' w- k, @3 P6 K  a9 f3 Q
[
+ \$ x& }- `2 ]/ }( U3 d1 I, k  intersection?   ;; true if the patch is at the intersection of two roads
$ L# h! o: x8 \* B  y: M: z- b# _- T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 I/ T* L/ E- c9 n, |0 V' O
                  ;; false for a non-intersection patches.( o# U5 t, V( ~* b. u8 _+ e
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 c* h- L2 L' \* a# c; b8 J                  ;; world.  -1 for non-intersection patches.- J. V  k. ^# e6 t' K
  my-column       ;; the column of the intersection counting from the upper left corner of the  z' D7 [; p1 _6 r7 Q5 q2 h6 l) m- n
                  ;; world.  -1 for non-intersection patches.- G0 R8 g, o( a. _
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# S0 ]3 [1 ~  k. ]3 n/ v
  auto?           ;; whether or not this intersection will switch automatically.3 ~- m3 _1 \" ^% u4 J8 ]3 j
                  ;; false for non-intersection patches.7 t  v% K' }6 [" r$ c% q. B
]9 ?5 E, G; c% h$ j8 w/ I+ C

& L& k7 V. n% ]- m2 g! w' w+ \; P: x6 N
;;;;;;;;;;;;;;;;;;;;;;
& f+ }) a; q0 D$ X/ }' p% u;; Setup Procedures ;;
- Z' D/ r( u* `! O6 m  a;;;;;;;;;;;;;;;;;;;;;;* v, K2 H" {" Q1 N* v5 D9 ]2 u
* P; D1 }" H: [' L; N( v$ |' F
;; Initialize the display by giving the global and patch variables initial values.
7 l8 N1 m9 ?6 e6 a;; Create num-cars of turtles if there are enough road patches for one turtle to2 P3 {" B0 g4 }5 k' b; H
;; be created per road patch. Set up the plots.
5 [+ \. U& j- M& zto setup
; g) ^2 m5 j( g  R: {( F  ca
/ M) i  u  O9 t3 K" i  setup-globals
& K: t3 T, t( A, Z; S
% D) G+ m1 q* ^  V& t; ^+ y  ;; First we ask the patches to draw themselves and set up a few variables
. T2 f" q* S% q: x3 F. |0 F  setup-patches
3 E! G, R: c) {1 F$ a' n5 ^  make-current one-of intersections# g8 J7 h+ ]% v' D9 N' i
  label-current
7 b) }6 v) Z! g5 e! m
7 }5 {# F0 W9 |. U9 A  set-default-shape turtles "car"
9 K/ i! J& [* S6 n2 B  _9 }' A7 H6 Y/ E2 C& [2 U+ T- J
  if (num-cars > count roads)
7 L% w6 h6 R8 k9 A' ~  [
+ R+ W9 d9 S5 U/ j9 b5 X& L    user-message (word "There are too many cars for the amount of "
4 }3 x2 U& _' ^) Q& K+ s                       "road.  Either increase the amount of roads "$ W9 R' H' o5 z5 e9 t/ k3 L- M
                       "by increasing the GRID-SIZE-X or "+ b! O0 I+ w4 E# K" p, X
                       "GRID-SIZE-Y sliders, or decrease the "
4 j! x& ?' t- }* E9 e                       "number of cars by lowering the NUMBER slider.\n"
- }9 H5 B  ~6 Q: U2 K! s; d& U                       "The setup has stopped.")* g4 N6 U. P% I3 z; A3 T) X
    stop
6 o' [7 g' h# Q. F  ]
4 I7 f% h) Y; i+ T" F% a9 F
7 r2 e- {$ e' P  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* X* i; [; d) Y/ f  crt num-cars
9 h) P( a& |1 Z# {, a  [
! R% `' g5 V& s! z6 p    setup-cars% m* X, ^% h, x+ J! y
    set-car-color( y" }4 a) {6 a6 f" x! h
    record-data- S1 a$ \) r- k! P( i
  ]0 A, ~4 ^* F! g$ _$ _7 F

: s4 m0 [/ c2 h- V1 y  ;; give the turtles an initial speed* f$ M3 a! w% S) b0 B! r) A; ~' z
  ask turtles [ set-car-speed ]
* @; h3 o1 {8 t9 l
! P% e. m& ~8 e* g  ^$ d  reset-ticks
$ e2 M  {- R- \3 Vend/ S, |* n. ^$ @. S! U: T* Y
9 s9 V& t" }- _( b& q# V
;; Initialize the global variables to appropriate values
1 \" b+ D5 X5 I) l% c+ {' uto setup-globals
$ Q1 ?# p9 i4 m/ }8 p; m, ^4 H  set current-light nobody ;; just for now, since there are no lights yet; ~1 w# @) e8 y
  set phase 0( E& ~' t; Y3 Y- W% p
  set num-cars-stopped 0$ V3 j, p9 @. h
  set grid-x-inc world-width / grid-size-x
. Q. Q+ _/ d. N! \) |- I* r6 J2 i  set grid-y-inc world-height / grid-size-y
+ @2 @+ }5 H# s2 Y  p) V, }& ~" I* U5 U; H! `8 l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# n5 P: Q- d) u4 N
  set acceleration 0.099
( I8 C) J  O$ B. Nend
' m0 V3 V7 e  p* l; `8 \" n/ `5 w6 z- A  I, `
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: ?9 e/ }! X# o& z;; and initialize the traffic lights to one setting
% p) N0 i) S5 Dto setup-patches! B( m9 {( U+ M5 f$ v
  ;; initialize the patch-owned variables and color the patches to a base-color! x% K0 m7 w) u9 V* C
  ask patches6 l, ^; m7 N( G
  [% U8 Y' ~3 m$ D& {* Q: w8 g, [- i3 f
    set intersection? false
/ y1 i# y7 G, u2 j2 H7 H( ?$ U' k    set auto? false9 U2 y8 a' R2 z! \
    set green-light-up? true" D. J* q' ~; r/ M
    set my-row -13 `4 Q, p( u8 Q& q% T
    set my-column -1" W4 R0 {. ~9 m- v- t  d
    set my-phase -1
7 }( B: B. q* l0 ]    set pcolor brown + 3+ c; ~* T( }7 M! Z# M  w7 i4 y/ x7 _( @
  ]
  ]3 f+ C* a  F2 W5 g0 D+ m; G- n$ G8 l: N0 |& s' p
  ;; initialize the global variables that hold patch agentsets
! V  s4 o5 ^: i1 _+ o9 l  ?. _3 g  set roads patches with0 R0 g' U% b8 ~; H1 u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, ?, E! u7 R! V' A4 |8 V5 e# {. ~$ D  g, S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 g% j! R+ G" t4 r  set intersections roads with
$ K& g! B5 x- G* X* W8 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 h1 M/ s$ o- U$ X4 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" I4 O% H+ z5 k' c( C  \# @" c
$ z9 t+ T$ O5 X; s8 ]  E- o. r5 V7 Z; m
  ask roads [ set pcolor white ]
; W  }7 @) @4 \* \0 t    setup-intersections, d3 z9 x& y! Y8 a( o3 U4 X
end: |4 g% o4 V5 L# A7 d
其中定义道路的句子,如下所示,是什么意思啊?8 H8 d! G! S, ?4 Q; s* \0 e3 M) Z
set roads patches with% g, S/ b5 k+ z, I7 V) s' o% C% N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, d3 w' L' \/ J9 d0 @9 d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  Z4 q0 {- z1 H: z1 [! K* a" G4 Y5 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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