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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。2 f% A: {4 u, Z' M: J: S
netlogo自带的social science--traffic grid这一例子当中,
9 ], |+ o7 N5 H9 F( |1 F1 D1 Hglobals
( x4 B2 Q6 s! B2 V0 ^6 B[  W; @  H- n  W
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
2 K9 h1 G: T% j0 C1 @  grid-y-inc               ;; the amount of patches in between two roads in the y direction; Q/ S5 W. i% J- E
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  o8 h1 x. b  M3 j/ c% [                           ;; it is to accelerate or decelerate
' T, [9 q4 i( j+ c& y  phase                    ;; keeps track of the phase; F" f5 s$ s. f9 d; F' {- k
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 L  E: n0 m" X/ Z, f4 F  current-light            ;; the currently selected light( Z" d& s& N% e5 }9 p! |
( j* V; L9 h9 D: Z0 d0 v4 O# h
  ;; patch agentsets+ f& b7 ~1 |, ~" j' j: h4 L  ~+ Q
  intersections ;; agentset containing the patches that are intersections  O1 ]; k, o, v& v: |- F" B! U  q
  roads         ;; agentset containing the patches that are roads
- {7 ?' _' P+ s7 d2 [], T5 K: y3 m, Y0 f' v: D

; L) S' f; @$ V: U2 u# Rturtles-own& v" X$ S$ Y) W: G* f% o
[6 k4 P8 }$ P. A$ d2 u+ I4 y
  speed     ;; the speed of the turtle7 i1 c  V6 L1 R- e- ?" T! I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( x/ X& c( C+ ?$ ]% T, o
  wait-time ;; the amount of time since the last time a turtle has moved
) V4 Y' E# u9 a5 J]* C: o2 Z( f' P" J. _8 y

( F, {6 z5 t: I$ s" g9 Hpatches-own
) s  Y4 Z+ d' k" ]: g, t[
' j) B2 l6 Z& I8 w  intersection?   ;; true if the patch is at the intersection of two roads' z$ l9 b  E/ q0 g# A* c0 m1 y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 f$ r" L7 }' z' _, u! n( G) {                  ;; false for a non-intersection patches.
4 u' _  J4 u0 h7 d; f  my-row          ;; the row of the intersection counting from the upper left corner of the: H" I8 B% f+ P- ]. v- J
                  ;; world.  -1 for non-intersection patches.
/ M9 i. A$ Z# K  my-column       ;; the column of the intersection counting from the upper left corner of the
/ k; ~' ^8 @& ^$ f; x                  ;; world.  -1 for non-intersection patches.
$ l# h5 \' o9 N$ I! Z  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- _* g, a9 T# M1 N  L  auto?           ;; whether or not this intersection will switch automatically.4 z- e/ `7 Q. U" f2 x
                  ;; false for non-intersection patches.
" p3 z, e0 R, {4 S& J. D]8 d* h/ K( n! `5 T+ Y  m& U" b
1 i& t/ s: Z9 {- b

, }1 v  D0 `6 b5 u9 A5 [;;;;;;;;;;;;;;;;;;;;;;
: B" e2 j1 x+ @; Z5 q9 V3 J;; Setup Procedures ;;
8 f, t+ |/ G' B9 f, x3 z! R& i6 u;;;;;;;;;;;;;;;;;;;;;;
9 h; C- E' d$ \/ v8 `
8 z0 l, _6 H* \- x9 {7 V& ];; Initialize the display by giving the global and patch variables initial values.
# R  F4 {: _' P/ F* ^4 I;; Create num-cars of turtles if there are enough road patches for one turtle to* i( H, s) @- I1 @0 e0 _$ e
;; be created per road patch. Set up the plots.$ M0 `  _: f3 h. {, M
to setup* r2 f, b2 v; w) G* u! N
  ca
9 |9 p4 |- L1 r# U, k  setup-globals1 P" ^3 U" F0 v* O
! h$ W- r1 U4 d$ z' c- i# [9 ]
  ;; First we ask the patches to draw themselves and set up a few variables8 S5 M1 d1 q0 [$ H/ k) V; g% h7 T
  setup-patches, z' [2 ?8 T  a# o6 j" ~0 z; `
  make-current one-of intersections
' g, N* M7 B- r+ |" d+ D  label-current
% ^/ z7 d0 U( X5 F6 d7 e; ^. J9 E! o2 D& G
  set-default-shape turtles "car"7 h$ z5 B( e1 v! S% O2 n

9 N6 t3 R2 a) _2 |2 p8 a$ N, T  if (num-cars > count roads)
8 d' E( }/ Y8 |+ R, ]+ ?6 W$ J: y; t3 A  [  n4 X6 L. L7 x/ c
    user-message (word "There are too many cars for the amount of "
/ ]" d: R6 y6 L* r                       "road.  Either increase the amount of roads "' d  h( k5 c3 Y
                       "by increasing the GRID-SIZE-X or "% j* E( L/ R$ K( F6 L, x
                       "GRID-SIZE-Y sliders, or decrease the "- ]% b" e( c2 Q# n5 u/ A9 |0 l8 `
                       "number of cars by lowering the NUMBER slider.\n"
& r8 r8 P: ~# Y& f+ l                       "The setup has stopped.")
7 i5 Q" e) N# Q' f- M$ U    stop! A, K! Q+ p! J( Q# O' e  U
  ]. e. ?- ~5 f" }" k; N

2 J0 {1 E7 r& R3 _  [  Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) U. q: k& d  q% X' ~  crt num-cars) ~" o% S* G9 v
  [
: h- {- A, M6 e9 U    setup-cars
# y6 S7 x, |0 w) L1 G2 b) Z    set-car-color. \* u  L) r) D# N. H
    record-data: W+ }" g9 o/ I$ K! P
  ]
7 n' N( {- |5 U
0 s7 K& _+ W; ^9 I* j# @" T$ a  ;; give the turtles an initial speed
1 n7 s; P9 H  k( B  ask turtles [ set-car-speed ]$ |+ p+ y6 l. H8 G+ U0 D
0 ~+ u. {; T8 ]: S( |
  reset-ticks
3 E/ o- {- L" {end2 R; N) N  H2 u/ [5 P' g% S7 e
# N: ^4 \* g; N7 a
;; Initialize the global variables to appropriate values
6 G) K" [% e6 W' D) L& uto setup-globals
% ~# K% L/ |( s: R  set current-light nobody ;; just for now, since there are no lights yet3 J" ~* n. [" R
  set phase 0% ^4 K% s- e% I
  set num-cars-stopped 0
! s9 l* U9 l5 z! q7 b/ L" W# J  set grid-x-inc world-width / grid-size-x
# D* e2 u* ^, e/ y; H( g  set grid-y-inc world-height / grid-size-y
% [. X1 J5 b/ n9 ]+ D2 Z: o& L" g& X) u1 w
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' ^' d$ D: P( \' C1 t  set acceleration 0.099
. w. h1 U; U: I$ M, T1 `4 Qend
" a! m. q% y6 t2 N* \& @, F1 E* E  P( T- K% {' V, e1 `- u: g0 g5 u
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% T  ~) w0 ]  S- h;; and initialize the traffic lights to one setting
# w8 y' I* _. I7 F  a8 Y3 gto setup-patches. _- e- n3 @; u
  ;; initialize the patch-owned variables and color the patches to a base-color
' z  |: n# [( L* ^$ Z  ask patches" x7 T- e! f; |4 X7 s0 A4 t
  [2 e4 s% E( g6 Y; T
    set intersection? false
( ]. c1 m$ K) E* B! L  a; c5 c/ ^    set auto? false
8 D) C# T/ \6 a( c0 y8 B( D+ M6 q    set green-light-up? true1 l4 w! F8 B( c9 k% y( \
    set my-row -1
7 i: j9 A" T, N+ Z* l    set my-column -1
2 J1 \* l& V& c0 m! o4 }% ~* _    set my-phase -1  `; `; t  {) t, O
    set pcolor brown + 35 I0 h. t  [  q8 ~! `% D2 r
  ]
2 S9 Y- M& n' l! Q- m3 w5 M5 q" c6 ^+ ]8 _& S, P# E
  ;; initialize the global variables that hold patch agentsets$ g4 ^( S. O5 d% L1 W7 \, O2 V
  set roads patches with
) c6 I4 J2 U: L# Z+ V. r. J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! f9 Z3 U% J0 S$ D5 q+ M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 _0 G) E" D  o5 q5 }1 X  R  set intersections roads with4 y5 D) h" q# O3 R5 m8 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" D( J6 X) D" I& Z7 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% }, ^0 D0 @( h; h0 f
- O. @9 A' E) ?6 l! `& A2 _+ ]
  ask roads [ set pcolor white ]
0 F+ u6 |8 d1 b& U( I    setup-intersections
" D0 T- d/ @# v3 W. v9 \end
/ e8 {% M  }3 \* D* M/ G其中定义道路的句子,如下所示,是什么意思啊?9 B- V# A* ^7 m9 n) S9 |* F
set roads patches with
0 }- z2 J/ h5 c6 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 @% T6 e3 u# ?* I6 k9 [6 d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- M9 ?  V3 U& ^  U" r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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