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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。. u. k# a* m. T9 {
netlogo自带的social science--traffic grid这一例子当中," R# e: ]# z5 L' {' b
globals
2 {) W% `+ v! B: x[% m; Q8 K- ]6 ?5 F; o$ z3 H. V3 A
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! B) n' J7 t, z. K  grid-y-inc               ;; the amount of patches in between two roads in the y direction" p/ D( F/ W+ }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) I, Z9 J3 O# L# C: l                           ;; it is to accelerate or decelerate
3 Z' q/ u8 Q$ r) L7 S  phase                    ;; keeps track of the phase: E2 A1 L# r! g1 Q+ f! L
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
; t0 {3 O  M1 |, }* M$ V  current-light            ;; the currently selected light6 p7 a6 c' I9 G$ R( e& B) X

+ m0 C  i: K$ c1 H  ;; patch agentsets8 g% F* f$ d! z3 c
  intersections ;; agentset containing the patches that are intersections
+ A/ D; w  Z' p7 a  roads         ;; agentset containing the patches that are roads0 P1 P, v- m2 I0 k' b3 r# Q
]  K. N, ^' [$ N& V9 E& ?

) g* o4 s! ^( z3 {6 Uturtles-own" s! }5 h2 o2 ]1 d8 Y. t5 W. p
[
' q* Q, n% V9 F2 Q$ o  speed     ;; the speed of the turtle) ?) K+ S% o" W, O  Y9 g9 \0 u
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 H3 N& v: t% T6 g
  wait-time ;; the amount of time since the last time a turtle has moved
0 A" B$ ^! |: ?, t, m$ t, W]1 f; o5 }; H* A) q% B1 p. t, P4 A

+ B6 Z/ Q3 R$ Fpatches-own
  ?( c" Q! b3 |% O0 o[
8 K! w9 F2 C2 a+ }2 f  intersection?   ;; true if the patch is at the intersection of two roads
$ v  F0 j# q: F+ P  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ g5 D4 c) E3 S  f5 [8 \# n7 J6 ~                  ;; false for a non-intersection patches.; L+ U8 h+ a1 K3 l
  my-row          ;; the row of the intersection counting from the upper left corner of the4 b! z; r) Y1 Q7 A8 |5 \
                  ;; world.  -1 for non-intersection patches.
+ p# _- G. F/ c$ A& G  my-column       ;; the column of the intersection counting from the upper left corner of the  C# Q6 ]$ q& G& J4 g! s+ P
                  ;; world.  -1 for non-intersection patches.$ U: {+ \; h8 p2 D) H9 B
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' j& W! g% j& p) k& }  auto?           ;; whether or not this intersection will switch automatically.; w1 d# N% c# m3 M% H
                  ;; false for non-intersection patches.* z$ w+ i. h/ B% i3 e: O# }
]8 `3 }% S% f; W6 b) d0 o, q- P
7 Y/ m9 K; p5 `

' a! u, ^% z: q! q# r/ u;;;;;;;;;;;;;;;;;;;;;;
8 G) \2 g3 R0 y;; Setup Procedures ;;- B: R) b2 H8 _: G- M) M
;;;;;;;;;;;;;;;;;;;;;;
) }9 O1 r- ^( G  I
) v. x( |6 s1 z8 w% V% @. O;; Initialize the display by giving the global and patch variables initial values.
* {1 I0 k9 ^& ^' W;; Create num-cars of turtles if there are enough road patches for one turtle to( M) |8 E5 p# e1 b
;; be created per road patch. Set up the plots.
& N; s& }! a. ^to setup( q& R* e0 v9 G3 E) e
  ca
* h# e, I5 x: a1 E! S! D1 K  setup-globals
. H! m' Y, ~0 d2 C8 F; r$ W0 j3 c# c, {
  ;; First we ask the patches to draw themselves and set up a few variables
4 U( G2 i/ c- T, Z2 x  setup-patches
/ X# e' M5 u2 u  V& v" \  make-current one-of intersections
- P# v' T. d& k) U' P5 B; J# i/ D  label-current' k% g' J$ w- ?; T/ G- L, u

, Q" D% a' M0 m, n" D  set-default-shape turtles "car"
% U) J( F$ j4 p# M; H
  ]9 D& E& b; i# |* M: ?: {$ e  if (num-cars > count roads)
; n; f' X, H1 a/ I: f  [; H1 ]: H3 l  z) g, J' x1 H
    user-message (word "There are too many cars for the amount of "
; ]$ J' p* Q! A. P- H/ g                       "road.  Either increase the amount of roads "
  s; f1 R# L. }) t6 ~  F5 t. @                       "by increasing the GRID-SIZE-X or "
# T4 o+ K2 q0 s0 X                       "GRID-SIZE-Y sliders, or decrease the "
) c& n+ D+ k- ]/ B* ^* Z! F2 ~                       "number of cars by lowering the NUMBER slider.\n"2 x- J* p$ |8 t1 B; Q1 u
                       "The setup has stopped."). a( r# z6 x# s' i# E
    stop( ?6 q8 G3 e1 m% U. I0 k; J' W' u
  ]7 s- ?1 `: y, {6 u( y  ?
, g" L: e1 `$ J+ Y4 k! L* n$ |
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 f4 F! R3 I. u0 z
  crt num-cars
, x! W% \+ G3 U6 X5 z7 i7 \: H& A& _/ X  [" h" F/ |) Z$ N
    setup-cars6 Q9 ~4 g5 y& i) I# p" s3 a4 {
    set-car-color: T4 @6 z- M$ s; P1 B
    record-data- q4 ^: q* Y+ a+ `
  ]4 F7 @6 C9 f! z1 y' Q6 D/ l/ @
8 z9 M* C: w% G) x& o
  ;; give the turtles an initial speed; O8 Z' ]1 `6 `2 f9 V
  ask turtles [ set-car-speed ]) j: s$ v0 [4 ]% V4 G
  U1 t8 D, u7 Q. i0 P: S- h! _
  reset-ticks, J; Y5 C$ t6 J
end% x# n7 U' f$ l3 x: q7 J
1 a- H  z0 O+ w1 H- a/ A
;; Initialize the global variables to appropriate values+ u  v/ ?3 C7 P: Q3 P$ V; {
to setup-globals  P9 L) B1 R; w0 _) `
  set current-light nobody ;; just for now, since there are no lights yet; }" U3 ~. \2 ^+ o
  set phase 0$ j2 P) c* \( s' u" @( T
  set num-cars-stopped 0+ n6 Q5 `( C) H4 z3 v, H
  set grid-x-inc world-width / grid-size-x9 }" G9 |# a& Z) w# Z. ?
  set grid-y-inc world-height / grid-size-y& b! o" k$ f: a: _$ Y
, p3 ~, F; F$ T8 O
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 `1 f, i3 Z  F/ Z0 N  set acceleration 0.0998 V0 ^8 _9 @) ]& }
end
8 u' i4 z0 f! Y2 [2 h+ |5 `" _# W  Y3 e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
6 c6 T1 x7 k: c# o2 M+ p+ t;; and initialize the traffic lights to one setting
4 W/ T+ k; H# S) Z1 ?to setup-patches
( M& r& t5 s2 ~' z/ e  ;; initialize the patch-owned variables and color the patches to a base-color
7 T! ^: z0 M; ~' Y3 r  ask patches
9 ^# R- e7 @" @: }  [& z* e$ l: A9 F5 G5 r# y; z
    set intersection? false
+ c) d: q4 u! [2 ^    set auto? false* X- J4 D0 Y  V/ E2 y
    set green-light-up? true1 A0 ]! A7 w% t4 N' V4 C6 _
    set my-row -1
" c7 d0 T  P: V9 M4 y    set my-column -1
3 |- A# D) J! n! T# }$ L, R    set my-phase -14 _- |; ~5 d+ ]0 o' b
    set pcolor brown + 32 ^' p5 f& ?  a6 h
  ]1 l! v* [8 v, Y' {
$ x9 I1 |7 k$ [/ A9 ^
  ;; initialize the global variables that hold patch agentsets# W/ U3 ~" ?( \' n6 Q# G" j
  set roads patches with: O! X& k/ X! W6 W& ^9 j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 {0 P( M5 @, l6 `( k$ I* N" r4 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 `  _6 j2 O4 `- y1 W8 t5 g/ Q  set intersections roads with
% F% o1 X; `* `/ S( X* Q4 G7 V% v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: C  n0 E! {( \3 Z, U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( P2 P% [: }6 Y: L1 U2 s- c: [
/ X/ L1 z, H  S% R% U  ask roads [ set pcolor white ]
' s* W- r, i/ `    setup-intersections
1 G' |. w, l2 ?7 Q! ]end6 ^( d! ?  Q  H" _
其中定义道路的句子,如下所示,是什么意思啊?. W  c+ x4 s( ^; t
set roads patches with
* G" y- N/ {1 {" k% S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 \& l2 Z+ e; ^# Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ H- W# `% g) e: Z+ e5 I  X  k& u- X
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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