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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。
6 Z. S! V, F4 e. K3 t& t; xnetlogo自带的social science--traffic grid这一例子当中,
/ K0 q& x8 X0 Y3 G) S1 G+ M$ Bglobals; v+ B6 |0 w0 _8 G3 m
[( S3 F5 V1 g4 J9 S% ^. V
  grid-x-inc               ;; the amount of patches in between two roads in the x direction( x0 V: z7 E* c5 V4 M
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 J( Y+ E! D. x  E8 x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% S9 D4 U- F, w  ?1 [; K                           ;; it is to accelerate or decelerate* F! t# p6 N8 [7 R. ?) u, D  s
  phase                    ;; keeps track of the phase
4 |4 E( u' g! v" E  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 R2 a# H% T7 Y; A  current-light            ;; the currently selected light
$ ~' i3 z( w5 V/ V" G  r7 M2 {/ F$ o! v
  ;; patch agentsets& C. O  ?" Q! j  r6 @
  intersections ;; agentset containing the patches that are intersections
( {2 ?" c3 N5 o0 ?  roads         ;; agentset containing the patches that are roads
) v. i. p6 M/ x9 W$ Z0 t% v]
$ j5 F7 i$ d% {+ ~: z6 r4 T0 l: S. t2 r/ D5 H! K
turtles-own
5 q' J4 G) c% S  m8 I. W[
* z! E2 ]- k, F1 ?8 y9 o  speed     ;; the speed of the turtle
' O3 f' [# @' Y$ O  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, \, u6 y! n( L  wait-time ;; the amount of time since the last time a turtle has moved3 R$ ]" p, f+ _! ~- T) q; `
]. {* w+ B+ g" b8 K
9 t% \# g. Q' I1 m4 v! S
patches-own
/ {% e7 n! q' x% t: H  }! e[+ I! q. x' `" F3 P5 h: r# N! d
  intersection?   ;; true if the patch is at the intersection of two roads4 p: u6 r" s) N$ v( y' t6 ^. n
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 Y# }7 p" ^4 [' a8 v/ |$ _1 m0 k
                  ;; false for a non-intersection patches.4 w8 G) {/ j, ?6 X- \: P
  my-row          ;; the row of the intersection counting from the upper left corner of the) |# a" B7 n& z( `5 c
                  ;; world.  -1 for non-intersection patches.- S. j5 h& }# W5 ^( h
  my-column       ;; the column of the intersection counting from the upper left corner of the/ M0 M2 w9 G4 K- v
                  ;; world.  -1 for non-intersection patches.: {5 O0 s; k8 C6 ]. @
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 [" D9 D" ?% F7 c0 C0 R  auto?           ;; whether or not this intersection will switch automatically.
9 z% l* c% [  p4 R                  ;; false for non-intersection patches.1 y' t0 [% y- C3 b+ a' ]
]
; o- f' @" a; h: D" r. R! D% \& D1 f% r: J7 j8 V, z0 ]
& M. v9 V$ a- i# y4 z/ J
;;;;;;;;;;;;;;;;;;;;;;8 y2 b/ a" j  ]" m, q6 S) E( O
;; Setup Procedures ;;0 D2 x* K+ q# q, z9 b# g/ ?
;;;;;;;;;;;;;;;;;;;;;;
$ {" k# h; ~4 L
5 T* r& c, [5 G+ J" C  x0 S;; Initialize the display by giving the global and patch variables initial values.$ E3 E( A! F  K& c1 t+ e* M
;; Create num-cars of turtles if there are enough road patches for one turtle to; Z  G7 g1 Q6 e
;; be created per road patch. Set up the plots.
$ t+ r* a  b# g$ }0 h5 `, W: A, W7 F& k  {to setup
6 T, S; x2 d: Y  ca
5 H) x- b8 A7 L6 x  setup-globals1 T7 s3 r& A2 u4 ~

7 q6 e3 t6 F: q5 w9 p  ;; First we ask the patches to draw themselves and set up a few variables0 f, `4 p0 j" s+ k/ @
  setup-patches4 ]* K- P6 F- d; g
  make-current one-of intersections
6 I1 w$ N4 [" R* y6 K* Q0 m  label-current$ {6 O9 P2 D  ^+ B) ?- l
# w! A: @5 {% E5 D. W. Q; W% E
  set-default-shape turtles "car"$ o: [# ]  O4 m
- x  @- L, p5 @3 \# l- I& \
  if (num-cars > count roads)
/ {3 I, v9 o. J2 K  [) j5 l& f2 f% k4 H
    user-message (word "There are too many cars for the amount of ") I3 u' H( W( [2 j  p6 i
                       "road.  Either increase the amount of roads "/ p2 C! Z4 v9 r/ \! s+ g
                       "by increasing the GRID-SIZE-X or "
# |/ \, j" D$ B9 O( z- l                       "GRID-SIZE-Y sliders, or decrease the "$ C& s% m1 l& T
                       "number of cars by lowering the NUMBER slider.\n"
2 r( J4 F* D; B! z1 ~% F  X                       "The setup has stopped.")& A5 o: S2 x4 D. ?- _3 k
    stop; _; `. P7 z# ]! V, I0 H- c! P- r# x
  ]! d! G, x  K/ j- D) C5 I
# A  G* q1 G; a
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color* W4 [! e' X) R! i+ z& f
  crt num-cars
2 S# y$ X7 b, P3 y  [# m* D- g5 e  k3 V0 B( w
    setup-cars% X  v+ E3 A  l8 v
    set-car-color
% k3 V! z! g# U' s    record-data) l+ L; [0 j) g7 M
  ]% g9 o& U' }4 [( N+ N% {
1 c5 s9 x0 \2 e/ D' }5 ]8 Q
  ;; give the turtles an initial speed4 T) Y' f& C7 g
  ask turtles [ set-car-speed ]
) `* Z- |- q3 L4 M+ e" ?7 |8 V( G- f7 N1 k
  reset-ticks
  @$ J- D+ b# V2 j+ w( a! Dend
; B: W" r$ p( M$ B
0 _9 v+ X$ h1 N, t- F+ a7 g7 f! V;; Initialize the global variables to appropriate values6 E8 ]2 k6 K: G8 R: ]* [' B3 m
to setup-globals9 E2 k& K. L( U" \# {. ~
  set current-light nobody ;; just for now, since there are no lights yet  ]* V* j) [5 j% r
  set phase 0, N/ H# ^( [2 j4 v3 E3 p" Q; A+ C% l
  set num-cars-stopped 0
. ]9 B. N0 O) E  j  set grid-x-inc world-width / grid-size-x' L3 U! e" u/ m0 [
  set grid-y-inc world-height / grid-size-y% f6 a  f# j3 H% v
/ i8 _: X1 i' P" p9 x1 c- Q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- z$ r% c  c7 y" R: q  set acceleration 0.099$ C- n/ Z6 o' b, h- z! {. _; o; t
end0 t& T7 e( l4 X* }8 I5 I

& b/ S* O8 q) ]2 b$ y8 l# _$ p, e. N" ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( k  u8 T5 n' e4 U;; and initialize the traffic lights to one setting* O8 y; M9 B" v3 Q7 i% J8 z2 z, _. G
to setup-patches
0 c' s+ e+ u- l' _  ;; initialize the patch-owned variables and color the patches to a base-color
3 v  U  l$ S; Z  ask patches
# [# [% N# d: k# {7 H% Q' }  [
& y1 ]& p- y, S. j# X    set intersection? false
( y$ ]; |" K+ Q/ Q5 g8 n    set auto? false
9 e4 G5 z' c& a; A. {5 t    set green-light-up? true( g' W0 E/ U3 I, ?0 l6 P
    set my-row -1
; |- P2 B  m# F6 V) d( H. d    set my-column -1
; z" i4 _- D+ G/ X' Y! [    set my-phase -1
* g- K, X/ `$ b    set pcolor brown + 3
  N# S5 N- w: Q6 O" C8 f5 s1 _  ]! g; q; v& z. S) L

9 r3 r0 L& m3 r& _9 H4 x9 P4 z  ;; initialize the global variables that hold patch agentsets
1 K; D5 Z0 \0 v  set roads patches with
! E1 c2 {. E6 v. B2 c- h; b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- V' ^  y% B8 T4 P    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 G6 m5 N5 O. L, h' l$ ?  set intersections roads with. C6 X7 f, l0 t/ V5 C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% k! [+ t8 E* o4 D. [2 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. m$ s0 N7 I. [' K  `
5 O. h; Y$ H9 v! q5 ^
  ask roads [ set pcolor white ]
: p: V6 Y, R; ]/ F' [    setup-intersections
) T. g& Y( U( j4 t8 _, s- z8 Eend
) }' M! P/ h! `) C其中定义道路的句子,如下所示,是什么意思啊?
  Y. F. J' w- W" I set roads patches with  l- e! e  u0 O4 g5 _, _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 ^  b& Q( C5 \8 n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  A, D8 u" G" m8 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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