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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。: u. Q$ g$ p" z- q; v. @, l
netlogo自带的social science--traffic grid这一例子当中,
& n' J# o% m* I( n: A  w+ Vglobals0 Y! f2 x! {$ d
[
9 P7 l. h1 V- }+ ^5 y; f8 K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" i5 Z* L' H% \) \! g0 k  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! g! k  ~4 o  D8 T7 D  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( u3 Y2 X/ Y1 t9 J* W4 g2 R- A* D
                           ;; it is to accelerate or decelerate
: [! E5 ?% b2 e& v  phase                    ;; keeps track of the phase8 \. l/ j, J0 V9 W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 V  i- j! }' c9 u1 [; h7 k
  current-light            ;; the currently selected light5 w/ |, m$ b" c. B
, W+ u+ y& \6 k/ m
  ;; patch agentsets0 V! \4 [* x& M
  intersections ;; agentset containing the patches that are intersections
/ J9 o, P# Q+ K2 I" b! H  roads         ;; agentset containing the patches that are roads
" j1 p$ v- z7 m]
4 v( D  w  r4 i( z, ~! Q" J/ A4 w- W) @" O% H! d3 \6 _8 Z
turtles-own
; t* ^& C6 T, u- C! P( {. y0 u9 i* F5 w[
8 H2 {' ?* U, @9 h) I' E/ z  speed     ;; the speed of the turtle
( |1 W3 L$ f1 n* Z- m1 c. g  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 f5 F& W; X) B7 G' y3 P6 ?  wait-time ;; the amount of time since the last time a turtle has moved6 [% i/ M4 v* }6 y9 S
]
/ s' {- v4 w5 [, N( @3 V/ W/ \- d* Y. l7 z) G& \# X& x' |
patches-own
; M% n. Q- P" j' H[
8 ~- q& D% Q" i  intersection?   ;; true if the patch is at the intersection of two roads
9 b* z. j! F) ^% w" c8 D  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* Q% L- u- m( f. P
                  ;; false for a non-intersection patches., @4 p$ `* \) D' U! l1 z
  my-row          ;; the row of the intersection counting from the upper left corner of the. X( F, m/ b2 j6 O
                  ;; world.  -1 for non-intersection patches.4 p& |2 [' `) b7 t6 N' ]. _
  my-column       ;; the column of the intersection counting from the upper left corner of the
/ I$ D* h8 m5 Q/ Y( \                  ;; world.  -1 for non-intersection patches.
- [8 I, O& b4 X6 p  q4 V3 [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 g0 G+ C- R4 R* \1 b9 i* u  auto?           ;; whether or not this intersection will switch automatically.- H8 n9 I# c1 C4 P6 Q6 v/ G% G
                  ;; false for non-intersection patches.
2 O7 y) V0 J$ P]: c& T* @9 v# L* w( ~

% {5 \/ d% T# Z7 H& @* }  U
$ G2 B: m9 T! ?1 ^  h# C;;;;;;;;;;;;;;;;;;;;;;# R! ^8 m  E1 I7 I5 S0 B/ e
;; Setup Procedures ;;& `0 m/ A3 G0 E& g" Z
;;;;;;;;;;;;;;;;;;;;;;
% x# g1 S% _# K& _  B
  k; |7 C3 w8 q" [;; Initialize the display by giving the global and patch variables initial values.: M. Y7 l7 e9 f7 g+ I8 i7 c
;; Create num-cars of turtles if there are enough road patches for one turtle to
; W+ `9 M) P6 @& W, W;; be created per road patch. Set up the plots.
" t0 O9 L  o; S( M) x5 jto setup
: g- {- {2 Z+ o+ n0 j3 S  s  ca! w; \" }/ \, H
  setup-globals
  O1 P) p4 D' K
! Q( V1 f8 Y0 g4 B* z+ ?  ;; First we ask the patches to draw themselves and set up a few variables+ Y4 n0 j& R% H
  setup-patches
" @7 h9 I  Y* K* @+ p! `- U* T  make-current one-of intersections9 I! A2 }/ u4 P; P
  label-current
% Z2 a6 r8 y$ T& @& e' O7 k& j2 l$ i9 ~! q3 z
  set-default-shape turtles "car"' C7 ]& y4 ?2 U) m% L
; ~: N$ O: |+ d3 \
  if (num-cars > count roads)
2 c% V% m( X* ~3 v% c8 w4 W  [2 F  ]# ]9 a- S; @6 V% N! d
    user-message (word "There are too many cars for the amount of "
8 J' {0 B8 v( }: M# L1 a- I( ]                       "road.  Either increase the amount of roads "' t8 h: k! T2 G$ v* J! a
                       "by increasing the GRID-SIZE-X or "
: }( w9 }" h, B$ p; c+ X5 M1 q; |, P                       "GRID-SIZE-Y sliders, or decrease the "
3 S% d) k* y( {! s1 g# H* i1 N: Q                       "number of cars by lowering the NUMBER slider.\n"0 `+ {- D2 }4 n( P
                       "The setup has stopped.")
* x; ?" I1 a' k1 x) f; z: q% o  P    stop: h' g. S6 K) R1 w
  ]
' G! ~* k" w+ u( l; h& o- {
  P) |! P3 _5 p; U, q: V7 D) @  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- }6 [* o, Y# p; z  crt num-cars5 V5 X* A/ j- @7 O/ y) r
  [
5 q4 Y; H0 _' }# @+ e    setup-cars) H5 L& z5 |% P# n
    set-car-color7 u0 @$ ~$ a" c4 B. T* A  {
    record-data
& X3 b( g0 i' ]- m+ ~9 s  ]
( y$ a8 g0 D; _8 y+ g' S+ ]# P6 E: x, X, I  H
  ;; give the turtles an initial speed/ Y3 k# x$ e$ M4 g; T
  ask turtles [ set-car-speed ]! ]; [0 j, m, a( ^3 t) F! B

+ i( O' J0 ]3 J/ P+ i& i, f6 N/ M$ G  reset-ticks0 S5 U5 \: @' ?. ~; Q# b
end
+ F! c& M& T$ K# G; w' D( q/ a& S8 N# E' J+ p3 |3 i
;; Initialize the global variables to appropriate values
6 g+ p! A  M) [$ [- s9 F$ U" xto setup-globals+ ?, X. t* _* b6 ?( p
  set current-light nobody ;; just for now, since there are no lights yet
$ o0 H9 v2 i0 C$ `% ?- D  set phase 0
# ^0 t6 ]) n4 n! m  v$ d. v  set num-cars-stopped 0
2 P9 J4 N: Z; A  set grid-x-inc world-width / grid-size-x
7 U/ _; g1 L3 E# D6 B  set grid-y-inc world-height / grid-size-y: d" y+ M- R! h" A9 f+ A

8 `( W# m$ _' w1 Q  k9 z0 \  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary9 k, C" }1 N4 Q; R0 v
  set acceleration 0.0995 _* [$ }5 {- w2 h+ Y0 F; m
end
4 @2 M! A8 l0 g8 H" ^2 Q$ h9 G- N! D: \# i) ?  b' B) `0 C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( [& g/ E& O7 B& w& N& M;; and initialize the traffic lights to one setting
4 r) X" u8 _+ f& a7 f& n1 yto setup-patches3 E; h6 E  }8 `  J( Z& ^
  ;; initialize the patch-owned variables and color the patches to a base-color
9 r6 ~; J6 r% e) V% \; U  ask patches
/ q' U5 c0 Z  \+ W  [& l) p8 {* |, T; D3 p
    set intersection? false' f" T  O4 b' {  v, O3 ?
    set auto? false; b  D# t; Q1 ~2 Y) ~+ V% V
    set green-light-up? true4 D; Z8 a& t  S: A) E: n
    set my-row -18 h% a9 Q+ r$ l) E
    set my-column -1
( _) ]- A1 j8 }% T9 ^    set my-phase -1; z$ H  d7 Q! h$ G7 h) }
    set pcolor brown + 3' X4 n5 {9 ]! [6 c+ @0 B) U$ h' R
  ]! |& h* m+ i! U

6 v& f3 d: M$ T$ l9 K  ;; initialize the global variables that hold patch agentsets
; i7 }- a7 _3 I) x( G. d  set roads patches with8 Z1 m. V0 H: x- y6 f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 B' g8 N) B( @; e$ v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) a* v: W- u% g' B5 A) ]
  set intersections roads with
  u3 G5 W, s; D) h  \1 R. \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% c) H9 p" }, b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ U% G! o- O/ B8 a! G$ s5 g( M/ r4 ?) d( r% J
  ask roads [ set pcolor white ]
3 ]1 K% O7 X; L    setup-intersections; s# v$ o) C1 V: m
end- f  ?2 U" c- w" b8 t$ U0 N
其中定义道路的句子,如下所示,是什么意思啊?. R2 ?0 I6 y7 I6 Z( ~1 N8 C
set roads patches with
5 ], n2 P: S) @# a$ e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 C& D, F/ F0 h& E' F9 T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  a, ~" H/ I8 e  U& H$ V
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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