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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。
/ N$ h& }. F- p' l& B% {- Tnetlogo自带的social science--traffic grid这一例子当中,) ?* M3 x. V2 F& \9 c- U- H
globals4 _. Z- _* [5 J4 x( J' i
[1 U- O3 E4 ~1 ]( Z; O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 r2 H7 S) l0 z! g. ?5 Y* G. i( t9 r6 |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, v" b! H3 ?' q2 e! ?" ]: {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ D, T7 Z9 A' q* K3 w6 O/ v: A4 @: R                           ;; it is to accelerate or decelerate
* \1 F! k, V+ u2 U. d+ D  phase                    ;; keeps track of the phase
( B$ A- R: {; P2 g9 Y# X+ V  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' k; h6 c) F7 ~. ^, g9 m1 R  current-light            ;; the currently selected light2 ?9 ?* l, }/ @9 ?) x9 G

/ @$ x' @& p) ~1 _3 H  ;; patch agentsets' O# b+ J7 `* l: x5 F. e
  intersections ;; agentset containing the patches that are intersections
1 O, S5 e  o2 I  roads         ;; agentset containing the patches that are roads8 g+ t/ W- a" T  Q$ X$ N0 s
]
* y! A4 e+ |1 w- F+ z) Y  n9 v7 ]+ m2 }2 b5 L
turtles-own" W+ W; f4 j* a* S
[0 k( |: U( k$ T
  speed     ;; the speed of the turtle
' b3 m) d4 ^( c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( {1 d4 |1 w+ q  wait-time ;; the amount of time since the last time a turtle has moved# G! N5 D" T' n& X4 }
]
6 W! C! i* w) F4 ~; ]% O/ [. D  m& _. X' P& F. g, R" A  h. R* f
patches-own6 _- U" O4 P& m% j
[, f6 @! [& g$ y& n! }
  intersection?   ;; true if the patch is at the intersection of two roads
& [* x8 J2 j$ P/ {+ c( b& M& ~% |& N4 M  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 r7 `" y* V2 V; H& ~" l0 d* @                  ;; false for a non-intersection patches.
  ]3 H6 `6 Q+ B! Y3 L  my-row          ;; the row of the intersection counting from the upper left corner of the8 o7 A: o) Q/ U
                  ;; world.  -1 for non-intersection patches.
; j7 g& ^3 Y2 E- A9 J+ t  my-column       ;; the column of the intersection counting from the upper left corner of the& H+ ~2 q6 a2 B8 H2 U5 X
                  ;; world.  -1 for non-intersection patches.$ @% d: q/ S' O$ N! L9 j6 O
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& F. p2 P  b* }. ?  auto?           ;; whether or not this intersection will switch automatically.
9 r6 C) M1 y. v                  ;; false for non-intersection patches.
, F1 K! Z) V# y5 o5 d) V]0 V# l8 y2 G& I# p# o0 E6 T  K
- n# a- n" G5 F; D+ ^* N- X4 ?
: M$ [1 [5 S  e7 m" L
;;;;;;;;;;;;;;;;;;;;;;4 H) B' M  X% m5 T7 g
;; Setup Procedures ;;
# l/ m6 j( I2 I;;;;;;;;;;;;;;;;;;;;;;
% P7 @; F" X* p' O6 P8 [
. K% J1 C, N2 S1 ]+ F7 k, B) s5 g7 _;; Initialize the display by giving the global and patch variables initial values.) W9 s, l+ g8 Y- K5 @2 E: h
;; Create num-cars of turtles if there are enough road patches for one turtle to
% ^4 r8 W! Q/ K;; be created per road patch. Set up the plots.  X3 a9 y; ?2 j( K. G
to setup8 ~2 m/ H' F& O* k1 G5 Q
  ca
, R: t: l( |* u# c3 i  setup-globals
# e& A8 M1 i$ `# T+ M% Y% s, g$ |, B' V1 _2 H7 n3 O
  ;; First we ask the patches to draw themselves and set up a few variables, G! X9 @3 R% @3 ?# @7 q
  setup-patches
* l' g; w- T8 u  make-current one-of intersections# v2 b7 A" m- \2 k; }+ X
  label-current2 L( `/ b" o# i( `

7 ~3 v& C1 S- Z# Y+ p# Q  set-default-shape turtles "car"" V6 ]4 e* }2 b- K9 D
5 h0 K7 h0 Z5 t" S* x8 k( w; i
  if (num-cars > count roads)6 k: O! L! K/ u8 l1 l  r7 |
  [
8 @. x4 l% _" {4 n1 x3 b- g/ e    user-message (word "There are too many cars for the amount of "5 {' ?3 j/ v. n7 a! T
                       "road.  Either increase the amount of roads "
" f- e5 [: w* v2 l$ |- Z, w  z+ N0 `& a                       "by increasing the GRID-SIZE-X or "  n3 e) t) D" n0 y" h7 y
                       "GRID-SIZE-Y sliders, or decrease the "% s* h3 ~' o, T& U! N) L8 X
                       "number of cars by lowering the NUMBER slider.\n"! J* Y# ~* R* G, m( V9 l
                       "The setup has stopped.")
$ j1 q. f( \& e$ I% P$ x    stop
% P  m! Q1 J' s5 x- ^3 [$ L  ]
$ g4 Y) Z7 Y; A! N, [/ k' u: y2 C9 O$ ?4 c. ?
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
7 `+ F8 G6 q0 C6 H  crt num-cars
5 J' |. G* X' R5 P+ X/ o0 y1 a  [
3 n: Z, b$ Z$ U' X* x2 n4 ?+ A    setup-cars& E! `) J- L8 o% g! i
    set-car-color
4 M# _& ]8 s, T3 J9 \    record-data/ S9 D) H% q  b/ b/ D
  ]; D. Y1 B1 k$ b, L6 K2 i8 f
8 G& q1 G; u5 Y6 C
  ;; give the turtles an initial speed
  b) ]4 c* X3 O7 c! i+ U6 ^  ask turtles [ set-car-speed ]
7 M$ x- Q7 [9 E( j+ j7 n1 S! L* w7 v( U2 l# J; S5 G7 O
  reset-ticks
" C" e% h/ _$ m  iend
5 ?# g: ~# `7 Q% f# A9 R7 E, [; ]7 g, V. \2 i6 X; E1 [4 z# w  t! e
;; Initialize the global variables to appropriate values
# F) B; b, C+ W: F2 u( w1 _to setup-globals
" H- x! j) i. H3 k  set current-light nobody ;; just for now, since there are no lights yet2 {4 K! G$ }* a; U* @8 i7 p
  set phase 0
& S: h6 G3 n+ u$ }8 v  c. R# e2 |  set num-cars-stopped 0
0 S+ Z  ^; _: z# f+ G. Y* y  set grid-x-inc world-width / grid-size-x8 k- Z1 M6 y" U( n3 z, p2 c* e
  set grid-y-inc world-height / grid-size-y5 s8 P. l. E  |

9 F% i4 _, x% U7 i, h* t; `  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 F0 @( T- {. J4 {2 \. n  set acceleration 0.0990 E5 z: z3 ^  v5 I% Z
end
2 W8 F& H& R) c1 B7 ~' q
6 y! J  j7 R1 T' H9 h- A;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 z; }$ z" o3 p- A6 d8 x
;; and initialize the traffic lights to one setting
# ~+ \3 x2 J  {1 x# mto setup-patches" q8 D2 ]4 z$ n3 I- r6 X0 \
  ;; initialize the patch-owned variables and color the patches to a base-color
7 Q# \7 q2 l" B3 X, \& q8 ?9 H  ask patches
8 _* K2 }  B3 I; r. G  [
; _  A) ]* u3 I/ E    set intersection? false3 w' ?' Z- K" \
    set auto? false& @+ M( h$ G" n% N
    set green-light-up? true
' `8 |. y7 J+ R0 h" g- ?    set my-row -1
1 k3 U: ~1 |; o3 p- P% y    set my-column -12 m' W/ i$ x0 O) b: A' Q2 q
    set my-phase -11 {/ L& x# N9 }) `7 |% a
    set pcolor brown + 3
4 V5 T" ~/ q) D/ W+ |8 C( _7 D% M1 E  ]
4 w: C0 B8 K7 I* e) [3 S6 x4 H1 P6 X, h
  ;; initialize the global variables that hold patch agentsets" c) H/ m. t+ ~, X0 b
  set roads patches with
  V- b! ^1 a% s! b3 h    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 a8 d3 a; o8 V8 F0 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ i( |% J. ]# i  set intersections roads with* x( {: q! C( W; `, H
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# F/ m$ n9 Y7 }' j. s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 i3 m5 [& y0 ~" b2 p9 A4 G. i) O* ]/ I: M9 }
  ask roads [ set pcolor white ]' h: \; s# Z6 D7 w
    setup-intersections
5 w" J6 C+ _) `% x9 D0 Tend, `* c& V3 \/ \! X/ g$ C$ V+ m
其中定义道路的句子,如下所示,是什么意思啊?& f( n( h. ]* H
set roads patches with
8 c- a+ x# @5 `4 M& A* d: N5 c. F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 P6 j+ _1 t5 X, i8 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 M: ^# f9 B* h/ E6 _6 S* {( t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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