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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。2 f- {  Q2 r  _; h
netlogo自带的social science--traffic grid这一例子当中,
! A8 _  d; R6 H* lglobals
6 w3 F* A. s3 {* Q& A[  ~9 ?1 Q; v5 }* g6 t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- r& a8 A- E& E: O! h8 L8 n  grid-y-inc               ;; the amount of patches in between two roads in the y direction8 s+ M% Z( U% i* ]: D
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% Y$ g( H" H$ \# F$ M$ H                           ;; it is to accelerate or decelerate1 B" f1 |% I& ]1 U" ?9 x- F
  phase                    ;; keeps track of the phase! y) n4 A1 _; y# ?7 G; _) E
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ B- }8 e2 g. k7 t! N6 z7 ~. o5 S
  current-light            ;; the currently selected light
' b1 v! T" K, a1 @* |9 W0 X& Y% ?. v* ~& j
  ;; patch agentsets# r' c( T* D4 ~, a; X
  intersections ;; agentset containing the patches that are intersections& m2 f; b" J, ~5 ?0 n! p& K
  roads         ;; agentset containing the patches that are roads  X& ^+ h0 r$ ?
]
5 C# _: Y9 l5 `3 J: b) N6 i0 x" E( l) V; X  s
turtles-own
- P, K; V* X$ y" E# s* y; _6 }4 N[
5 S) t  R; ]% A8 ~+ S  speed     ;; the speed of the turtle
$ I5 E* k1 E3 G( o3 [7 W  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! J! o! Q9 G  F: q. l9 z" [  wait-time ;; the amount of time since the last time a turtle has moved/ O: g# r, V2 _, W/ S
]
$ l4 o/ }% v' l5 c
( O  q' J) y$ qpatches-own
3 ?/ S! `5 r3 q- E7 `3 J& d, b[
5 A3 |. Q7 m; n8 ^" f) p8 E  intersection?   ;; true if the patch is at the intersection of two roads
+ X+ Y# i! W7 r0 L, A  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: M( m( H9 {0 I
                  ;; false for a non-intersection patches.% c/ f) I% d6 h- L# w% c( z
  my-row          ;; the row of the intersection counting from the upper left corner of the
% I& ?7 a, ^& p. F2 c! _5 D4 N, }  R( z                  ;; world.  -1 for non-intersection patches.6 j' X7 }8 U) d1 R( Y
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 ~. N) V# R  t% c                  ;; world.  -1 for non-intersection patches.
% l/ |1 `  l  c& y3 L* }3 r( F  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 c; L$ K9 X! H/ E" o
  auto?           ;; whether or not this intersection will switch automatically.
; ?6 Y8 @6 ?8 B% @                  ;; false for non-intersection patches.
2 E5 E* _0 c5 ~0 ^# C' \& L6 a]
' g7 }) n: R) o; C; ]6 d# K4 ~* |7 x$ J. S

9 h( K* [8 m$ O/ x8 i0 k8 [4 }: o( I;;;;;;;;;;;;;;;;;;;;;;& g" }% c& w0 F) m: N  Z& z& G
;; Setup Procedures ;;
; i7 R* D* e8 k  F( l. Y9 D  A* z;;;;;;;;;;;;;;;;;;;;;;# {4 G  u; o/ ?$ X% T8 n
# d* u3 h# I" X9 M
;; Initialize the display by giving the global and patch variables initial values.
3 Y. [" a. K6 p0 Y4 N. I;; Create num-cars of turtles if there are enough road patches for one turtle to
, a$ }# G# U4 @% ^* };; be created per road patch. Set up the plots.
: D$ Z; \5 U9 s# Y% E- e* @to setup
" R, @3 l1 p$ z  l  u* k4 g  ca- i! Z2 r! }7 w0 ^. P# b
  setup-globals
1 w( o  j& z8 n; J0 Q3 j4 T
( D; [3 ^/ q! v" v# ]! L  ;; First we ask the patches to draw themselves and set up a few variables# }8 m3 S) y! n8 t. _9 S
  setup-patches* {2 y5 ?2 U- u  _$ w
  make-current one-of intersections3 n% V& K8 `$ {1 i: J" i0 v) z
  label-current# n, m' U3 r) B: k4 _) g/ e: H
& W7 r+ \+ Y: y0 M3 N
  set-default-shape turtles "car"
! E: D$ y0 w0 l! l: O. i; ^2 m" {7 e8 \2 I! k8 S/ J/ ]
  if (num-cars > count roads)8 G$ L3 _! i* w' p
  [
; F9 t. S+ d5 U: Y3 l0 ]' e. @    user-message (word "There are too many cars for the amount of "+ Q% A# F* ]4 G- I3 J
                       "road.  Either increase the amount of roads "# {1 u. N$ x  c+ c
                       "by increasing the GRID-SIZE-X or ", I" ?7 A  M$ n; G6 r1 w
                       "GRID-SIZE-Y sliders, or decrease the ". C7 s3 }, O8 ^& }3 R0 M1 w( u
                       "number of cars by lowering the NUMBER slider.\n"
  A1 `& O% I4 k( y/ S                       "The setup has stopped.")( E8 J2 p5 ^, n: e  \0 `0 \
    stop% K0 F4 {4 y( n5 V  x
  ]
: X7 }6 @( _$ B( R: N/ B0 r4 o; ~9 [0 y2 G! K! b( A2 H; G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ Y1 w' q! W/ t3 a7 U
  crt num-cars
/ K+ w) Z3 s$ Z- w( a  [9 s- M6 n% j6 A' G5 f  u
    setup-cars
; C/ E+ l+ l' ?8 [7 U# J' D$ s    set-car-color2 W* {9 B2 [/ @+ h, ]
    record-data: q" |. ^; ~8 ~8 V+ z: O
  ]
. e* j; A/ ?/ b3 g* r- F) k5 k- K- D) c5 E6 Y6 h" D6 m% ^7 ^
  ;; give the turtles an initial speed
2 W- b1 X, s3 ?  B5 P  ask turtles [ set-car-speed ]' f: d  A3 Y1 L* H( C

# b2 j: G7 R9 n8 Z& @  reset-ticks; d8 ^- N; `/ L) N# O- b. I
end+ ]. F4 e4 P7 E

* ]2 {+ I8 @! a2 K, F% {;; Initialize the global variables to appropriate values9 A% ~2 W/ q) y
to setup-globals
) i" S( p9 V+ d  c  set current-light nobody ;; just for now, since there are no lights yet# h8 _. M; H0 `! c5 L# r% ]5 o
  set phase 07 L; k) ]& E$ q0 @1 L7 W2 S6 C
  set num-cars-stopped 03 B# g  O, }( L  S
  set grid-x-inc world-width / grid-size-x
" S* Q# ?  x0 E: C5 \" G) |& C  set grid-y-inc world-height / grid-size-y
1 [1 G5 f0 V! F. d" a5 t+ k
+ f& l, `) r0 e5 I  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  {& [% }% Q% O4 U$ l
  set acceleration 0.099
5 D$ ^" ?* M# W9 n$ w; c' o9 Yend
; s* k- Q5 [# k, L0 o( p. W( l! S
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
& `: W4 ~% @- O8 O' ];; and initialize the traffic lights to one setting
  e6 q; U' ?9 H; u& R* Xto setup-patches" @# h6 I7 _, ^
  ;; initialize the patch-owned variables and color the patches to a base-color
' k) l( p# b9 F4 ^  N/ T  ask patches
7 D$ [/ F4 w# F- @) r' Y! U  ?" k  [7 n/ }% E  _$ l) ~
    set intersection? false
% n0 G* j. y- a6 w" n0 `% \    set auto? false
: i) i: M( c' y' N  u7 q$ v    set green-light-up? true9 f' v, I4 u1 x0 A
    set my-row -1
) N) e: q" d8 y, m7 |; R; {6 k    set my-column -1# v* b4 W4 B1 K, ~& E
    set my-phase -1
' x, o; F9 y5 p2 P6 k9 ]" U& L  Z    set pcolor brown + 34 B" H1 S2 e+ d; q$ X+ d
  ]; g; T- K7 m4 i5 F( V' _
9 K  O* I; R3 o
  ;; initialize the global variables that hold patch agentsets) u& o3 S- _: M7 w* N) H1 P
  set roads patches with
( l) ^  J, X6 o5 C: V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 L$ o8 f- E- h1 }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 G1 E: N; Z0 g2 Q! y  set intersections roads with6 J' @4 I3 L8 W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( Y# S7 x7 x$ b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- X2 G6 M  ]: V9 J2 f
3 r  s) y# G; ]; q2 x5 L
  ask roads [ set pcolor white ]
2 E1 T/ H9 d* g6 C6 @    setup-intersections
% B- h8 z  ?1 xend
2 i' F; f+ d$ @8 C5 a; |其中定义道路的句子,如下所示,是什么意思啊?# @9 `9 h6 D  `; Z' S
set roads patches with6 k+ `0 R+ ^. s" v* W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! |2 Z" [, t& E( @  p+ c3 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 n7 x+ [7 D; Y/ P* F4 Z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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