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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。+ u7 w6 C! p  h' l/ K5 s- o( H
netlogo自带的social science--traffic grid这一例子当中,( `! x/ V' w, b
globals, D: h* U& w, P
[
6 E5 |5 A' L+ q5 |2 r7 N  Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- v! I& k* l$ \6 ]$ c  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ z5 V$ _( M  G" L1 `7 ?8 |1 w
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) I' z% @7 T( C  z0 B, K
                           ;; it is to accelerate or decelerate
( ~# w2 G5 x, ^  phase                    ;; keeps track of the phase
- T# z- D/ ~6 W+ I# h# e  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  v' g( L9 r8 r) d1 L
  current-light            ;; the currently selected light
$ g: [& l& ?9 K. ?3 S
+ ?3 a) c, k; n6 C. Z  ;; patch agentsets; E# `% i/ G7 J- k/ _2 K5 V3 P
  intersections ;; agentset containing the patches that are intersections1 _# W& v& k5 F3 I8 ]# y( X
  roads         ;; agentset containing the patches that are roads
- X5 B, P" \: P0 B% Q: s* _]
; J7 a2 k+ L/ @- M  w% \- i) ~' |' X" I
turtles-own
5 H" b* ~# s) t' N[# X! Q4 }' A. k- u# w4 W: e- v/ x
  speed     ;; the speed of the turtle
  f4 Z! @* K% _( {  [) ~1 {. c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( T7 @9 \, p9 V" r
  wait-time ;; the amount of time since the last time a turtle has moved; }: g' D, a3 U! [
]. d. G( Q$ b. V! z. n

) A. B( m. Z  y- O: i4 @4 Upatches-own+ ^/ N4 [& n8 o! q0 }
[) l2 k: g. t% S( G  C6 G
  intersection?   ;; true if the patch is at the intersection of two roads+ B. ~# P( P  D" p0 J
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ h8 t: {6 C9 ^3 H8 S, b2 w7 h' S
                  ;; false for a non-intersection patches.( T( b; c& ?2 B- M1 C
  my-row          ;; the row of the intersection counting from the upper left corner of the% S3 j. X4 }8 G9 n. n
                  ;; world.  -1 for non-intersection patches.
( q" b  O3 T; @- p9 w0 v  my-column       ;; the column of the intersection counting from the upper left corner of the
& P1 q( l8 ]) `. d" b% q4 @) B                  ;; world.  -1 for non-intersection patches.* R4 ~& E1 W5 Z1 b
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& F, O% F7 V7 z( v# c7 |7 `5 T
  auto?           ;; whether or not this intersection will switch automatically.
2 U! U$ D# u  ?# X: }. m# X" Y                  ;; false for non-intersection patches.7 V6 Z6 G8 E2 `2 I/ J* l, F) Y8 |
]
! B5 r: ~( o; e/ d) \  n: J% z' U% P0 \5 L: F% z/ l- W
+ @/ n0 A# i2 I! b& v/ z! \
;;;;;;;;;;;;;;;;;;;;;;8 c2 C" M, b9 f+ ~3 l9 N' P
;; Setup Procedures ;;. F: o$ ?' w: F
;;;;;;;;;;;;;;;;;;;;;;
; x5 @1 I- H! V9 ]! R0 ^* ?
8 M  C) H: O3 _. ^;; Initialize the display by giving the global and patch variables initial values./ U$ P, U( U5 g
;; Create num-cars of turtles if there are enough road patches for one turtle to
& l  ?6 M  K, d;; be created per road patch. Set up the plots.
" R& j$ Q! ^& I* E3 ito setup  a, E- r% g& z
  ca; i: U+ Q% ^# h0 Q
  setup-globals
. a: ^$ b  X. S$ y5 b; a2 V# N- z. X$ O, D- }
  ;; First we ask the patches to draw themselves and set up a few variables
& e% j! p5 D8 o" v  setup-patches& L* ^" }6 a9 c: n, W& d7 I) L: `: h) k
  make-current one-of intersections
: M9 x$ ~  d+ L6 a  label-current% h' W! G. q; u% d' p" ^0 L4 d

/ e6 D: W+ q6 P% k( q% G; L  set-default-shape turtles "car"- K: j" ^, |! m
$ h8 y, V7 {% o1 L4 z
  if (num-cars > count roads)
9 P2 {' Q8 U, L- W  [" M6 h1 j- q( }3 g  X/ a! s
    user-message (word "There are too many cars for the amount of "/ p5 L8 z7 p" x3 R: q
                       "road.  Either increase the amount of roads ", N2 ^! h& ~1 i3 x. h( P
                       "by increasing the GRID-SIZE-X or "
% [! X& A! m3 y4 f5 A1 K3 p                       "GRID-SIZE-Y sliders, or decrease the "
/ Y3 s& U8 m, I9 l5 ?$ |, u5 ~2 R/ \                       "number of cars by lowering the NUMBER slider.\n"
) @1 `  l$ `5 P7 _                       "The setup has stopped.")
- J+ u& I. `0 }+ R6 E) ^. f    stop% Y/ W4 r, u' T2 J& Q' W+ T
  ]+ x' Q4 `" {+ m. K) v9 c

# d5 @9 u% {* K" j$ S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 G1 `: u* }! u) r3 [
  crt num-cars  @# ]7 D3 ]& u& Q
  [' b7 X( u( }1 E
    setup-cars
$ [' c6 k7 t! s    set-car-color* {% a5 C! `0 P
    record-data# p3 B2 W, D, P5 C
  ]
3 E7 m4 y# C  v  k
. `' O) J1 y! s3 @7 l  ;; give the turtles an initial speed7 C3 z5 v, ~. H0 n
  ask turtles [ set-car-speed ]
8 |3 {1 v4 ]1 w3 ?- i9 W3 S. r- a7 O, [) X: W( y
  reset-ticks
) u; T) L2 `8 i9 i( y0 Hend
# a1 ~: K( M8 h) ~1 x
; w" I# o5 f# V# \0 b/ O1 D) T# S1 ~;; Initialize the global variables to appropriate values
, w8 a; V3 s& \: V3 Y+ y  ito setup-globals) I# a4 a) W6 N
  set current-light nobody ;; just for now, since there are no lights yet: S) e; ~3 n: I  A  l+ L) y
  set phase 0/ D: c7 \3 t3 j$ ^2 a
  set num-cars-stopped 0( K- R5 y4 ^8 _% H
  set grid-x-inc world-width / grid-size-x( Z( a2 T1 h9 n
  set grid-y-inc world-height / grid-size-y" ?0 V: a: A( _$ n

6 g2 r% ^+ k5 X5 I  k9 Y/ T, b4 R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# j8 Z' v9 k1 P1 U1 t1 U
  set acceleration 0.099/ I3 C3 ^5 y8 e0 s: R
end( H% D+ C* a, y/ f
& |. v6 s* M. w0 C- z2 ?  O
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* v. R% J, @  p- H$ j) [" f
;; and initialize the traffic lights to one setting$ o7 f/ D: }$ t) d/ b' ^
to setup-patches8 `- `& q3 k' |- t+ D; b
  ;; initialize the patch-owned variables and color the patches to a base-color
2 @# M; f# t( _% \$ j: F  ask patches
5 J0 e! x' M0 B& W' s- H" [  [
) k( E( ~) p' T6 T  g: |    set intersection? false
  N' f: B/ Y1 {    set auto? false0 |2 b9 o8 P4 \# \) L) t9 G
    set green-light-up? true
- \# Z2 j- i4 R! ~    set my-row -1
9 o+ g3 @4 a; S5 p( y9 K) {: \    set my-column -19 V  `- ~( p2 z- f0 p9 w6 Z
    set my-phase -1
9 M) u* H" v4 k2 `- P* s$ F    set pcolor brown + 3
2 B9 K/ U; U" `6 Q- c  ]2 y: K9 Y) l# Q1 Y& W8 N! ~* ^
/ a) y  j1 V+ H0 y. u% h
  ;; initialize the global variables that hold patch agentsets
8 u$ b+ Q! X- {8 b  _  set roads patches with# f! S: T" c- U) F- b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ I# s/ z* \7 \; A! W6 o# \3 G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 R+ ?. n1 u8 E
  set intersections roads with& \4 [2 ^  V3 W$ v6 ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) r6 p9 m7 Z8 Z: z& f) C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) o, [2 |4 F7 D, K  Q$ o

4 J3 x& Z* f  d# ]  ask roads [ set pcolor white ]
4 i/ k8 i' w6 R& W7 B    setup-intersections
6 K7 \  _+ t) M. bend
0 H- d# w$ z) H其中定义道路的句子,如下所示,是什么意思啊?5 P9 b# x  E0 i4 Y( i! J
set roads patches with3 ^9 h  r) g* M  t% D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! p% i: C1 {) o% q# \/ S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 x" e, f/ V7 I4 {8 _* ^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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