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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。
- d3 P; J! F% O7 L1 B% snetlogo自带的social science--traffic grid这一例子当中,  E0 k9 D6 x1 |' `% M) e
globals9 U8 m4 M( t2 z) j* ~# }5 e* W4 z
[
, l$ Q# J' c0 l; L( Z  grid-x-inc               ;; the amount of patches in between two roads in the x direction! L& A) j' i9 C% R0 |. R/ D
  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 W' Z1 n) g  ?% E# S. k: L
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if' r% G3 m. v$ V/ f# d& m- G
                           ;; it is to accelerate or decelerate- s! E% Y6 m3 v' p
  phase                    ;; keeps track of the phase
# f" P. @' D  k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ F$ g0 e# |- M, l; k( b. q& J  current-light            ;; the currently selected light. M8 q$ n/ s1 }" }
2 z* M! G) R2 Y4 N1 h
  ;; patch agentsets& y) d2 Q* l+ h$ M  r
  intersections ;; agentset containing the patches that are intersections
5 d. |% K; U5 U3 |; z  roads         ;; agentset containing the patches that are roads5 J! `* \0 e4 h- j0 U
]
4 P- u" X$ C1 W3 r
0 \. }7 f0 g# h8 `) Eturtles-own" X+ H6 K1 V( s0 y& \
[
8 B/ j+ H4 U. n0 Q" Y  speed     ;; the speed of the turtle1 p8 Z; w1 A  l5 ^. c! n, n+ Z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; y) t9 R8 f$ m+ \# d2 _, F  wait-time ;; the amount of time since the last time a turtle has moved
+ q" |" w# p% i+ z: o]
8 r5 y1 ^! w3 V) m! [( o/ B% @1 \% R' N2 w  f
patches-own1 v1 s) W, }- T& X$ h$ K
[
, O* m9 o! Q0 ~2 t! l" H$ A  intersection?   ;; true if the patch is at the intersection of two roads
7 P5 b! e- g- t: r: k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.& M& ?" c4 Z* `1 G5 a) A
                  ;; false for a non-intersection patches.3 T! V& T1 x1 Z2 E/ p$ C
  my-row          ;; the row of the intersection counting from the upper left corner of the2 L, Z+ e& w, K
                  ;; world.  -1 for non-intersection patches.) _9 O8 f& S0 x( ~; R
  my-column       ;; the column of the intersection counting from the upper left corner of the5 ]7 S& d6 ?7 l' ^, Z
                  ;; world.  -1 for non-intersection patches.% V4 E1 q8 R0 |! |- d3 ~5 d# r. R
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 f4 X6 O/ X; _* {/ s
  auto?           ;; whether or not this intersection will switch automatically.$ [" }* t/ J$ `" c; z& r
                  ;; false for non-intersection patches.
/ n: F. B) \! U7 P  S' k]
/ M: @* \! v, J0 r- q" U4 e- M7 ^3 W, V' a% h3 B1 K
# r/ a- ?) ^/ u
;;;;;;;;;;;;;;;;;;;;;;
; K: S9 m9 I8 f; _6 \;; Setup Procedures ;;
4 Q: K4 |. I# C5 D$ G  x( D+ J; [+ y;;;;;;;;;;;;;;;;;;;;;;( W  o! o- i& M
. M) J. b0 X$ a# A4 d% V8 t
;; Initialize the display by giving the global and patch variables initial values.
: L0 q, v' X, B. L;; Create num-cars of turtles if there are enough road patches for one turtle to5 z4 v/ E7 [! U: r, @4 t
;; be created per road patch. Set up the plots.
% T5 F7 ~( j4 z0 a0 Nto setup# J) ~8 b. U9 }8 n3 W: g
  ca9 }% y; I3 u  k6 K+ S+ {! D
  setup-globals+ i% O- w5 [' I; Q! W  M2 K% e5 ~

6 X( M/ A. L# H" r& ]: x  ;; First we ask the patches to draw themselves and set up a few variables
/ w& U6 C# T& h! W0 j8 d: P, ?  setup-patches
; S  m! N: d7 Y  make-current one-of intersections
+ Z0 c4 C; }9 L& P  label-current
/ ^( |! G* G3 f* p! @2 m! B. \' z  a- w: b. b9 s
  set-default-shape turtles "car"
, |! Q4 `: `! \4 i& ^( E4 Y- P" d- g6 B& J; V" s/ D2 O" J2 _' y
  if (num-cars > count roads)$ R% s7 H$ }; J: q0 K3 Y; z% y
  [# ~8 o5 d& Y2 J0 _" c
    user-message (word "There are too many cars for the amount of ") i. `5 v% E/ l  y& `
                       "road.  Either increase the amount of roads "- I8 i+ N8 B0 d- [. U
                       "by increasing the GRID-SIZE-X or "4 M; w8 ]) `+ N. l
                       "GRID-SIZE-Y sliders, or decrease the "
. r3 J0 c# r3 }* O8 }" g                       "number of cars by lowering the NUMBER slider.\n"- |1 {- C+ A7 O2 l3 V  @/ b4 r7 u
                       "The setup has stopped.")
: X8 P8 E# u: o) s$ s! L9 d) v    stop
1 c: s, o, E' a( n- w  ]% N' e( R6 t" r( e. ]
% f/ m  Q$ B# m4 x
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, l& H; j) l  t& I5 P  ?) I  crt num-cars+ o& \8 y% ?0 @/ k
  [
- c" L" j% z7 Q: y, I, A    setup-cars  j- r# k$ I0 `  F5 D" b7 h. i
    set-car-color0 W- {6 W( a( H9 B0 X
    record-data
$ {( @& A2 j( k% r/ a& @) l$ K2 W  ]
$ I- m1 m, j- u3 A) E* f$ T
2 N. @5 V% t5 N& Y4 I- R6 K! @  ;; give the turtles an initial speed
1 C5 E: n! _/ e$ S7 o. I  ask turtles [ set-car-speed ]0 y0 y' @1 Y( U: h: i7 g
$ @. y. s" j& K. ?& U
  reset-ticks& j& B# X5 e9 w1 F  D
end
: m. Q7 s6 ^# r, o8 e# \1 H
& _9 g  f7 b& c% I* C* ^;; Initialize the global variables to appropriate values! B" t/ C8 u) Y, C# s7 H
to setup-globals2 D% }( C( S  K3 h2 ]2 i( p  y
  set current-light nobody ;; just for now, since there are no lights yet# ~  o% t- z* `
  set phase 0
, f6 _) t, E( b; Q. D# X" [  set num-cars-stopped 06 o% u/ H! F0 U+ }0 O
  set grid-x-inc world-width / grid-size-x
, w& k, k1 m: b  set grid-y-inc world-height / grid-size-y
  V. C0 h( v2 r- u, }, t7 Q7 A2 `* s$ I1 g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 Z9 A& p% I( k  |/ G' T! L  set acceleration 0.099
' t' G* M4 X( u; H  D- w3 _end# U. m' K8 s4 S( t& M
' j" U/ d1 [, J$ \( j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 c/ @1 _, j7 L" A9 _, t;; and initialize the traffic lights to one setting4 |! u; @! H6 G+ f
to setup-patches
/ T# g0 A+ L- D. y9 _  ;; initialize the patch-owned variables and color the patches to a base-color9 ]# v1 g1 d+ m, k
  ask patches
: N# F/ \: p" ]* s+ U$ d+ y  [* P' ?6 k; p  i" Q  @8 z+ p
    set intersection? false
" D) `, T# l' o/ T& X: ~    set auto? false1 |, E2 I0 ~5 a% D
    set green-light-up? true
$ s7 n% [! W6 L0 r5 m    set my-row -1
2 [# I. Z9 r0 K% V    set my-column -1
( u$ B& D& \# G; a5 l# C; {/ ~# t    set my-phase -14 S2 r2 D3 I) v' O$ L: Z3 I
    set pcolor brown + 3
3 j3 x: a* D& _' z% W) i6 t  ]
$ I, D% K: K) }* a. r3 \- C1 E$ ^+ z
  ;; initialize the global variables that hold patch agentsets, t* m, I9 b8 Q4 \$ l8 B9 B0 H
  set roads patches with) A. K1 g" @9 v% M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 b: ?& j7 l0 B- G  r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( T7 ?( C4 e' p' o9 C# [
  set intersections roads with3 O3 Z7 d# l9 m4 z* d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 Q% J( n( j& @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! u; R- v6 ]; t* C+ m
" U) a/ b* j+ U7 p% C5 R% }  ask roads [ set pcolor white ]- E1 b. J  i* o$ @$ \
    setup-intersections
5 M9 }9 P7 n- O& }! L. A  f' }end# F2 z! H: l! O. g- _
其中定义道路的句子,如下所示,是什么意思啊?
4 e5 w9 y8 i  x$ ? set roads patches with# O- @! f  y' n9 A7 q2 Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- h. r3 Z9 x: `4 V7 w* \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; z1 D, @8 C1 x- H! O0 Q0 V# D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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