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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。
( E; f( u+ ?8 y- }; ?( @3 ^" Xnetlogo自带的social science--traffic grid这一例子当中,
; t) n9 z  ]- h( W" r9 |globals
/ K, k% d, ?* E$ |( z[: i7 h' S, s) j( \/ N3 j" u
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* `7 |, r- j) i, ^, N, `  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 W# ]' P1 X8 z& b& z# p
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ W' J2 I9 s- L1 B& H, A/ \                           ;; it is to accelerate or decelerate
# P) q7 h$ Q: _% H  phase                    ;; keeps track of the phase0 ?; T* E, k# K" [% N9 Y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 {- w" v1 z' D( r; @$ q0 |
  current-light            ;; the currently selected light, x4 \( _) }5 [
4 u! ~& ]2 \1 x. N/ J4 `2 s
  ;; patch agentsets
- z" l% o: e" S' R# \  intersections ;; agentset containing the patches that are intersections7 Q2 w: P* D- C0 s6 ^
  roads         ;; agentset containing the patches that are roads1 P. t" \- Q# c6 k, w
]
  h% u% y* @7 f0 I+ S7 ]- f6 n- y1 ]1 }9 d/ \3 g
turtles-own7 ]' u9 b' D, U0 U5 K
[- o5 ~( m6 T% {' l$ q
  speed     ;; the speed of the turtle
% W# @0 ^7 p7 \% C2 u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
8 H3 G* r7 D* ~2 J1 n* @  wait-time ;; the amount of time since the last time a turtle has moved
/ c  B. ^6 k, X9 |4 h]" x& @: N+ Z+ T8 x2 A1 X
4 ]& J3 p2 W/ F9 C/ r' g4 ~' D
patches-own) `7 ~. U+ ]/ |5 b7 x9 r4 ]
[
4 ^# k: K% f  U) C; X  intersection?   ;; true if the patch is at the intersection of two roads
- |9 M2 ?& v7 q1 F* ~2 L  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 |8 g, y) F) q                  ;; false for a non-intersection patches.
- J# |" ~5 _. i& X" M- w8 G  my-row          ;; the row of the intersection counting from the upper left corner of the# c3 X- _3 z$ ?! ~; k; y( p) N7 I
                  ;; world.  -1 for non-intersection patches.
6 {% b6 N0 C, Q7 J- y% R  my-column       ;; the column of the intersection counting from the upper left corner of the6 n$ }, N/ Q! \& a& U3 s# Q
                  ;; world.  -1 for non-intersection patches.& N$ K$ f3 Q4 j" C- H' t
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) }+ ]% X" B" ^4 q7 b! w5 c, m
  auto?           ;; whether or not this intersection will switch automatically.0 G/ @. f- o  w5 ^8 Y! T4 @% |
                  ;; false for non-intersection patches.) V9 T" r  E- D1 o% j! n: X
], i6 d5 n9 s" t0 Z, C* w+ z8 J
5 i2 \6 x7 |1 L) L. y& _. \! m
( k4 D8 p# u9 o* K9 A6 s0 w% i
;;;;;;;;;;;;;;;;;;;;;;
# J/ R3 |* r, j3 @;; Setup Procedures ;;4 i* n$ r. v0 ]& `
;;;;;;;;;;;;;;;;;;;;;;- s  D; _4 @: p
" Z4 Y) b+ K0 l( e1 J+ n
;; Initialize the display by giving the global and patch variables initial values.
8 c3 M6 M( l, p4 F; o' O. O. r;; Create num-cars of turtles if there are enough road patches for one turtle to$ d* r3 r7 k, {* [# @
;; be created per road patch. Set up the plots.2 w4 K; ?0 w# G
to setup( ?! W0 z# l  p. s! s' j* W
  ca
- e3 b! z0 U' L* H  setup-globals
# D. f# g) f0 ?3 z) u8 D' W3 @# B6 |
  ;; First we ask the patches to draw themselves and set up a few variables
* c; b! _8 n' h% T; T/ q5 Y/ e  setup-patches
( y: N3 v. Z( a3 p  make-current one-of intersections
6 w2 v- z2 ^1 g! F3 |  label-current
0 E, \* e; a% n2 e6 [
1 m/ E" g' [8 o8 x* z2 h# C( h* Q  set-default-shape turtles "car"/ o; I. v% ]3 c5 F) _

/ Z9 S$ M! X" j# ?4 T2 d' J4 O  if (num-cars > count roads)
/ [+ W. P1 a- b& m: K. N3 j7 b$ J! Z% Y  [
6 r  u- A$ I  f7 H7 s' s    user-message (word "There are too many cars for the amount of "
: D* O; [& H4 @) b& T                       "road.  Either increase the amount of roads "1 O% ^- M8 f$ z  k
                       "by increasing the GRID-SIZE-X or "4 @0 ?8 }, I0 _2 ?% y# ^
                       "GRID-SIZE-Y sliders, or decrease the "
- ~4 Z$ W/ \  N' m3 b) Y0 z                       "number of cars by lowering the NUMBER slider.\n"
! j  N2 b4 `8 @4 N$ o                       "The setup has stopped.")
5 u2 R3 H* O2 \& ?) g5 v    stop$ Q$ Y* L% X9 J1 V3 q
  ]
: |9 P* b, Q" E! s/ f6 P
; ~# e: |' ~% N( |$ T  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 ?! S8 u! J& x  crt num-cars0 a2 n4 u5 Q* O  P- z
  [
: F: K$ m  {. W4 c  J    setup-cars
+ D1 S% e5 T: N6 u    set-car-color9 _$ I7 R' f) q% s) C" w) k" k0 `6 ~; l
    record-data/ |1 _, L3 J5 Z2 f; y2 u( C3 s
  ]4 J$ A7 n4 w1 c: O& O: X/ o4 y

9 P' w4 x( C% v$ V$ t+ Z  ;; give the turtles an initial speed
! h: {4 D1 _' @2 y7 f5 K/ n+ E: U  ask turtles [ set-car-speed ]
7 Y  H8 i: A% M% j
6 C# M0 u+ H3 M& E0 r5 B% l  reset-ticks# l0 ^. G* _0 }4 r( Z; h
end4 j- a& J* L, T1 p  |/ c

; ]1 `2 \& _0 Q8 i% b6 L) C+ A5 z;; Initialize the global variables to appropriate values
; e* D2 f7 f! T' c0 `to setup-globals
! A0 ?) h) c) H3 g3 V  set current-light nobody ;; just for now, since there are no lights yet
9 ~8 ?9 G& C8 @: h- ?# F  R$ A  set phase 0
' G5 b+ ]  x- `: W- V' s- P% E  set num-cars-stopped 0& F8 m9 x/ x9 Q0 y! T$ R
  set grid-x-inc world-width / grid-size-x
6 A  H" O( }, L+ b) k- o8 E6 o  set grid-y-inc world-height / grid-size-y
6 z' Q4 \" Y8 l$ `
% d& o# v4 y- E( Q" I" ?0 p- A8 F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; J0 t$ Y" i/ M* q
  set acceleration 0.099) O& p0 k8 S( }$ O$ d4 ^
end
7 u4 A3 _9 C3 Q$ {! z- a! h# W0 L* H" ^& I7 P+ R5 x  N* K
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- P* X+ D$ n# d3 ~9 ?' }9 @* b/ [
;; and initialize the traffic lights to one setting5 _& R& ]$ d" ~) D
to setup-patches
8 v6 f0 _, Y) s8 P) d4 j4 p  ;; initialize the patch-owned variables and color the patches to a base-color2 h* U$ }6 ^7 f% X
  ask patches$ I# i8 F8 m" K+ A. f
  [
% e# y6 Q& {$ _6 M: x    set intersection? false
9 R4 `7 G; v% p" _9 n    set auto? false5 m. e7 J( ]9 x6 p) @) z
    set green-light-up? true) E+ y5 b5 i, P/ ?/ u
    set my-row -1
: T2 C6 y0 ?5 C6 \- q& a    set my-column -1* Y) Z1 P9 e: z; G; R: Z
    set my-phase -1% |8 p" V9 ^) n- z% P( D/ l+ r
    set pcolor brown + 3
+ E* }* p: X4 g7 w/ @5 e$ X; z  ]
. M  J% _* E$ v" s. p) o- H
) |" m: y+ q# C3 ^  ;; initialize the global variables that hold patch agentsets
5 I, G/ U3 G' G( Q# @  h$ K  set roads patches with" B5 p# F3 C' i0 H. ~4 T' b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 ^! T0 a5 m; W& b. d+ @% n8 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 J0 }: w1 m+ Q( Y- Z- O
  set intersections roads with
# T, F  Y  K! K# A8 ~4 ~) F5 L; W. G" y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
; p, h# G, _  D2 K/ m% G- p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- k7 I3 i# R5 G' ?9 _- J  a  `5 g
& c+ z: i6 N6 P7 `. j  ask roads [ set pcolor white ]
4 h/ S; d& d6 ~    setup-intersections- K6 K+ W" A9 e9 z4 ^1 e& D
end
! l, ^0 Y7 }7 U7 A, }其中定义道路的句子,如下所示,是什么意思啊?
& B( ~# f( }) J, f0 k set roads patches with
# x2 }4 b$ I) B+ K: Y, p- `# i; o: L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 d. ?4 ], n# O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 d7 b, A# r- U& J+ z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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