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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。4 c' y6 J- R% C6 K5 t
netlogo自带的social science--traffic grid这一例子当中,
- e) E8 F$ f" S+ Lglobals
5 ~& U# D5 E4 G; v+ X6 u# M[  c1 X9 p- r1 j. V; o
  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 ?( C+ a8 Z% Q
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ j  b7 D% k: ]" y. g
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if* O0 q4 B. Q6 A6 E2 Q% M! z+ T/ E
                           ;; it is to accelerate or decelerate4 i% X$ y: g3 ~: S
  phase                    ;; keeps track of the phase
$ `3 y  n- x* N( M5 O  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, L/ V% j+ _# n9 x+ b2 X1 x7 X  current-light            ;; the currently selected light
0 ^- s% L8 g9 `/ x- R& P5 w1 U8 q1 f- O* |. j  {
  ;; patch agentsets' J. F7 t! f3 v4 K
  intersections ;; agentset containing the patches that are intersections
1 v; ], [- t' L- T1 S$ e9 p3 Q  roads         ;; agentset containing the patches that are roads
$ {# H9 W6 h; z% q+ A! m5 J4 `]+ `5 |% w7 N- V; F

8 a+ a; M/ o' B% x" _. cturtles-own! ^$ l" B; O( [- h( p7 N) H
[- ]* {/ v2 B. d/ @+ q) P
  speed     ;; the speed of the turtle
! S# w/ u) m. X: Z- t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* L4 _( T* W3 d' n  wait-time ;; the amount of time since the last time a turtle has moved
$ C: D. h; S$ p  [  n$ z) m]
7 [. ~0 n4 H! `  }" G8 t
% M. K  e- U+ I8 B. \+ \patches-own
5 s. k: J3 b  _8 v[3 G' j- ?5 q3 u& n! K! B
  intersection?   ;; true if the patch is at the intersection of two roads
4 V8 L7 G' [& w( T5 ?/ \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 t3 \& P+ k! k$ A8 b1 B                  ;; false for a non-intersection patches.3 e. z& u- j& D
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 v. Q! M6 W5 o                  ;; world.  -1 for non-intersection patches.
0 U4 t# r: q8 `# Y9 s# t0 r0 e  my-column       ;; the column of the intersection counting from the upper left corner of the& j& |! s4 X7 j3 d8 Q: z
                  ;; world.  -1 for non-intersection patches.% G7 e4 i: G! p
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" w% t/ a! |; Q! {  auto?           ;; whether or not this intersection will switch automatically.
3 e; _/ E! c: D/ K1 Q                  ;; false for non-intersection patches.9 ^; \% O- v5 H
]* i# L. d5 }( @; G
5 J( O% E3 B4 i, L0 k

* n  d5 q3 Q# r;;;;;;;;;;;;;;;;;;;;;;
  ?' R  C( s9 P3 n! |# F, K;; Setup Procedures ;;
2 m! e8 j2 B! ]! V' E. ^6 U! c;;;;;;;;;;;;;;;;;;;;;;- P( i" x5 `! I4 n/ z
. |, S. W# B- l- e& L/ Q
;; Initialize the display by giving the global and patch variables initial values.7 h. j  [' |9 k: Z4 c$ `! {2 i! @
;; Create num-cars of turtles if there are enough road patches for one turtle to( e0 W5 n6 k+ {6 ~$ G
;; be created per road patch. Set up the plots." q; q$ A) \, X( ]) @8 W6 J
to setup
. t1 p0 z# ]. L% v- E  ca
5 i: P; `# |& U  setup-globals6 l. c! C& k. p( z; x6 M! M3 s
* Q6 @! V, B' n3 n  {
  ;; First we ask the patches to draw themselves and set up a few variables$ m* V: p3 o1 |% q
  setup-patches
" D7 s, o$ D3 v% l+ x2 N  make-current one-of intersections: ^' Q/ d3 s# k
  label-current
5 d- n  F/ {+ k4 r4 I* y% R, ^# D  v# q/ O- v7 F: E
  set-default-shape turtles "car"3 E, G( j/ [7 }% ~: j; B
2 [# v5 D' W& \) x0 \
  if (num-cars > count roads)
4 v; z" j, z! h1 U# \. F9 e/ M3 u' `  [* U3 P3 w9 [: n; d
    user-message (word "There are too many cars for the amount of "8 \5 M  `7 b. Z2 f& E% N
                       "road.  Either increase the amount of roads "
9 W. K. y+ W9 p7 I. @+ t. F: Q8 x                       "by increasing the GRID-SIZE-X or "
, h3 u7 {. F' ~# C5 N                       "GRID-SIZE-Y sliders, or decrease the "" O8 A; s2 h* T# j( f
                       "number of cars by lowering the NUMBER slider.\n"
( f4 e; ~4 \  P* L% ]                       "The setup has stopped."); v1 F: h; q& D6 J
    stop
! R& n( }2 m8 M+ W) a/ }3 Y: C8 W  ]$ [1 O2 j/ V) T/ r5 v, ~  @/ ?

! p/ H8 ^$ r/ q3 c  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, L. z# J1 _! T  [, h
  crt num-cars/ T. Q* p; N& D  H5 V
  [0 {5 l) _7 u" G* I6 j3 U9 s
    setup-cars
% U; h7 L+ ?1 }! @9 `    set-car-color
" q( o; X8 ?8 Y+ v% c- H2 l    record-data
0 L/ [, `) [- v  ]
# Y7 ~' i" R: U+ B/ V2 k5 q. M/ z/ S4 U; W) R. Z
  ;; give the turtles an initial speed
+ }2 n, ]" A$ }: p, O  ask turtles [ set-car-speed ]
* v* b+ d! c* a! D1 E3 S# F6 y- {7 s5 W
  reset-ticks8 e% @4 \7 J! U) s
end
  g, ?8 c8 ~2 T1 p' L! _; L$ n4 K4 ?% L$ A( n0 ?; ^( F& p
;; Initialize the global variables to appropriate values) M" v4 a: Q* t5 Z$ c( C4 _
to setup-globals
7 W- J% a/ @0 }9 |3 z' x4 }  set current-light nobody ;; just for now, since there are no lights yet
. n# {; {8 d( J* m! a  set phase 09 X' D  j0 p" c3 ]( z
  set num-cars-stopped 0% b. W, o1 v: B$ t
  set grid-x-inc world-width / grid-size-x
; [( K; L' R1 d* }4 Q6 t  set grid-y-inc world-height / grid-size-y  K& P2 B4 f8 H# G7 B

/ P3 d% v# [3 i& s5 h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 m7 N, f1 f. _+ c5 ?4 I3 H4 k  set acceleration 0.099' T4 O9 u6 P0 S  u; j3 l
end9 A$ r- L1 e6 d; W/ @) h% q& d) S5 I
' y" o+ r2 y, |2 r7 Z2 S; l2 v% V, T) C1 u
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
; j( m. P! ]$ F0 j$ f/ X# v- a;; and initialize the traffic lights to one setting
* e9 E0 ]5 {8 Y$ L' Jto setup-patches1 }) B4 o# F1 b3 Y7 e: F) h
  ;; initialize the patch-owned variables and color the patches to a base-color5 f7 m6 t" x9 e' _  G' ]) V
  ask patches1 Q* W5 A1 F6 M, i
  [
  B2 Q' E' c9 f  R( E    set intersection? false
, J4 m/ G0 m7 j# \# \    set auto? false
6 ?- K1 w  _8 _: y7 E2 X    set green-light-up? true
# K$ a2 r" O, k    set my-row -17 m) g9 t7 z* J' J" Y
    set my-column -1) {4 t6 R- z' b
    set my-phase -1, v. [: ^: m$ a# k4 R7 d
    set pcolor brown + 3
( l- w8 j! C/ p3 m  ]
/ T! }3 |& f7 \$ _, o' X  [+ T& _5 I; V
  ;; initialize the global variables that hold patch agentsets
3 D; [7 a' {# M9 L  set roads patches with2 l' ~6 L# `: @9 V' d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! L' S/ r! J" B( I! W: ?  a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; N, W6 O/ [$ F' s6 s5 Z
  set intersections roads with4 D9 x$ }/ a7 ?$ G+ x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# `# w9 f" P1 Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 ]# o. K) A% o
0 d6 d/ C, }1 |; i1 ~9 f  ask roads [ set pcolor white ]
4 G7 i9 \/ H7 y$ r    setup-intersections1 y( E6 j; l! J. a- e9 j
end7 Y. C7 e2 g( L4 W$ o
其中定义道路的句子,如下所示,是什么意思啊?
, n) @0 I( v+ o3 x6 g/ B: U9 {; Z set roads patches with
0 t. }1 |/ |: L8 a: ]3 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  T! f" l$ C- F$ i& I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# R/ G( C- o' ]0 Z; i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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