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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。
1 |2 F" }* e9 P+ e4 A% a# `6 {2 Mnetlogo自带的social science--traffic grid这一例子当中,' v5 p) }1 i9 `# g. q$ Q9 [' n
globals0 Z4 Y7 _$ u6 u0 j( Y
[
& z% {# R# z, O6 ?7 ^+ c  grid-x-inc               ;; the amount of patches in between two roads in the x direction: u& d4 s: u& ?! S- I3 D
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# P6 J+ e  X, k3 v% u; h: ^  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 A9 H9 c; }3 g7 ^; I
                           ;; it is to accelerate or decelerate
; U: {) I$ e1 V$ C5 B  phase                    ;; keeps track of the phase
% O* m1 L9 q6 J( }  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. d( z/ s1 @+ ]6 W
  current-light            ;; the currently selected light% M; |6 w$ A! s

; u$ A6 t2 a# h; @! Y: y  ;; patch agentsets3 W* x( f6 N+ @# z3 W1 L- R% v
  intersections ;; agentset containing the patches that are intersections% P: E6 @' q* Z8 U8 f/ v* t3 w
  roads         ;; agentset containing the patches that are roads
5 F; Q0 i& p8 a; _' G1 D. f+ ~]
: f" W! o7 H' L7 w/ _  H
! N/ ]; u& J. l9 A! s& Dturtles-own
7 u+ n5 D9 L( q[6 W; z$ R; C4 a2 b* y3 [$ v% ]7 C
  speed     ;; the speed of the turtle" k; |# W$ l5 {! I+ j" Y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 g: T  y, e, ^2 m1 \  N# Y
  wait-time ;; the amount of time since the last time a turtle has moved
# K; h1 `% {) L8 h5 G$ x" p# p]# }& Q. d( ^; d7 C5 z
  @; P( @# N1 F% l/ }. O: b
patches-own
- O, u8 z& ^0 M[
, ~/ `$ W0 \9 ^, a' ~, z) ?  intersection?   ;; true if the patch is at the intersection of two roads' O7 V0 z  o5 ~* t0 @& z% g( B
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 X7 V0 O! l, \( [$ f3 b                  ;; false for a non-intersection patches.
# W6 S3 T0 U* S3 R( r4 Y  my-row          ;; the row of the intersection counting from the upper left corner of the' W: m$ F& j, v. s( e6 o9 b: J) N
                  ;; world.  -1 for non-intersection patches.
! x, x' e* Y3 O. Y0 l. y0 O( P8 ^* T  my-column       ;; the column of the intersection counting from the upper left corner of the/ A7 y( Q4 _8 A$ [; w% L
                  ;; world.  -1 for non-intersection patches.0 g. a: O7 e; y6 M  O4 ~8 ]
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- N' _/ H) o, U! [& l$ f9 |
  auto?           ;; whether or not this intersection will switch automatically.% n8 y# W1 T! T5 J
                  ;; false for non-intersection patches.( b' \' m& C  h% T
]$ c- b. d- w' [, g9 I
5 p+ ?7 h8 L  Y

+ ]  B& F1 C' y" h: y7 A;;;;;;;;;;;;;;;;;;;;;;; z1 {$ g: u: Q! |7 g/ [7 f$ G
;; Setup Procedures ;;/ G- s8 g7 u; E4 _$ c
;;;;;;;;;;;;;;;;;;;;;;8 v# o& X! _4 w

2 ~, T  L4 R! b, B4 q: P0 X;; Initialize the display by giving the global and patch variables initial values.
9 M( Y4 }, s# o/ F;; Create num-cars of turtles if there are enough road patches for one turtle to
) J5 q9 L/ t- Z) o: W;; be created per road patch. Set up the plots.
0 G' j! s8 P' W0 Y3 sto setup
+ q# {8 Q6 ~6 H% Z' ^; f7 }  ca. L# `7 \7 H, L9 d
  setup-globals" h1 b- N  Y- R9 I" [, W. L
, q" b, Q# U4 C. w: \4 V5 O9 \
  ;; First we ask the patches to draw themselves and set up a few variables
6 ^* |- ]9 \" o& u; h- `! M: U9 D3 C  setup-patches+ D3 N" l% b/ x  R
  make-current one-of intersections, @6 a8 I) p; R% B6 a+ R
  label-current
2 d. @1 Z- N( J# i6 Q' c8 ~. \0 F' s& {: H
  set-default-shape turtles "car"2 U3 N3 t. X, u$ t' ~

) z( D8 ~5 A% Y0 h' I% O  if (num-cars > count roads)
7 _$ B0 Q. a7 _8 O/ K6 [  n  [
1 c4 w# K: w/ F* m7 w9 N    user-message (word "There are too many cars for the amount of "7 A9 y0 l& ~) t1 _8 Y
                       "road.  Either increase the amount of roads "
% X/ d6 P$ y  D0 h: z( M/ U                       "by increasing the GRID-SIZE-X or "& ~2 I/ Q4 Q# z( f4 E
                       "GRID-SIZE-Y sliders, or decrease the "$ M/ c& t& z2 U/ T* N
                       "number of cars by lowering the NUMBER slider.\n"
- S# {! C# U- B0 ]: ]                       "The setup has stopped.")
: x5 g, J  y; B4 z2 X    stop
1 F  |/ \5 T: Z  ]' z8 D) A0 K" l4 O' G4 D' U

3 t/ c7 C/ m0 k3 a, V9 n  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( x7 ~4 ^# a! w, g- P
  crt num-cars* Q  u2 A0 y# X2 }
  [. g# c' e1 u7 g7 d* R
    setup-cars
$ f" Q+ D: f" E# h' L  q    set-car-color
: }/ a, a" P* @    record-data
. A6 Z+ V8 w9 [) \9 ^  ]0 J- M, y7 _/ H( Z

4 o; d  n; \9 U" |( o( z  ;; give the turtles an initial speed
5 t* a2 U4 P; G2 l6 z- ]% y  ask turtles [ set-car-speed ], H8 V6 v  g9 [- Y7 R' b2 D3 @) U
* Q8 x- z: A# X5 M! V0 j
  reset-ticks
$ c# R. d+ T1 S; e2 Yend( z( C7 r; _+ _0 {, \( v! G# I
& b4 R* b- V2 X# `! f/ ]
;; Initialize the global variables to appropriate values6 N$ v- t/ }7 k  [
to setup-globals, k. |& P% A7 L& p' `
  set current-light nobody ;; just for now, since there are no lights yet, p5 t) O. L7 `( J" H# U- i: Z- k
  set phase 06 p) z9 C& v' @) U
  set num-cars-stopped 0" c+ F- T  u' u$ L8 ^$ ?6 {6 {
  set grid-x-inc world-width / grid-size-x
* l- G2 p- p( K' h  set grid-y-inc world-height / grid-size-y
. ?7 D) U5 r) @2 M3 X
6 T( w2 i5 z4 D4 V4 o& O$ N  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 t1 N# c9 T" Z" [3 n  set acceleration 0.099: L- w* V+ f1 O1 j/ ~, d; X
end. u$ G4 J9 C4 o; L; N5 }, O  S) c

6 l9 w( _9 B: w+ ^% A& u;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ q4 E1 b8 P) l  t
;; and initialize the traffic lights to one setting
4 N! B. T2 O9 F' t- {( Gto setup-patches" N- O2 l# m5 D0 a  g8 X
  ;; initialize the patch-owned variables and color the patches to a base-color6 V+ k% D( y+ h
  ask patches
; E  w, S6 k! A4 [$ U6 \6 U  [! m/ D) F4 n* M1 R' I* ]) H* X5 J
    set intersection? false, a! G2 Z$ d: X
    set auto? false
  }+ H: F5 |3 ]2 b6 A% g    set green-light-up? true
' c: Y2 }' V: _* }* I    set my-row -1
  g7 Q. a5 T3 m) A' s8 V1 t    set my-column -1
  b8 `5 e7 h; N: B* x1 P7 a, \    set my-phase -1
  `# i; b$ E% X    set pcolor brown + 3! f3 |& G. o. p! L2 p1 S4 v
  ]
) O/ M" t) z+ a/ {5 @) P! A
7 a8 ]5 F# M: O0 b  ;; initialize the global variables that hold patch agentsets' W) m0 i# I" C2 d# D, ?
  set roads patches with
% Z3 L+ Z3 j. s; G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 U) O/ j' H+ |. {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 a" u+ l2 A$ e  set intersections roads with# ?- D7 n/ w% A& s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 |) j3 |# l* }9 @( T( [1 h# @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% N' e  c6 k9 w/ b. p6 P5 r4 a
( n. n# `! T9 x+ M* a9 M0 O: p  ask roads [ set pcolor white ]5 w; C& M9 _' W2 B; Z6 L" p3 S
    setup-intersections
8 v+ c  x& _1 c# Y% v; _end7 r& ~4 T) t6 J* e+ S
其中定义道路的句子,如下所示,是什么意思啊?% V3 F! [; B, W/ X& J; x. I
set roads patches with# @3 l) S/ [$ q5 X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 S4 x( a. F$ m7 i7 ~& E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 @, {+ @# ~+ C  ^; w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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