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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。9 R& b  N8 Z5 N2 p( d
netlogo自带的social science--traffic grid这一例子当中,5 X! U& m% \* U( z& z! H
globals
5 z8 Z0 s3 {2 F! G/ c8 e% T% Y[9 j* l. U$ [/ ~9 D& b8 L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' s$ Y8 E+ x- Y+ P2 T9 }: f  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! V- u" u: E' q( M" [( X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 [3 x- y, Y' V
                           ;; it is to accelerate or decelerate
) D; ]" ~- ~- ]+ c  D. T2 V4 `/ W  phase                    ;; keeps track of the phase
. |6 i0 A; h( j% m3 A% W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, A. R/ ]9 R0 ?9 d
  current-light            ;; the currently selected light: B. A9 T. c8 K* `
0 j) I8 P+ d. Q& g9 A8 G
  ;; patch agentsets
+ U: _& G6 ]% p$ d  intersections ;; agentset containing the patches that are intersections0 B* L- X+ q  m/ k
  roads         ;; agentset containing the patches that are roads& f) P- ^" m/ G) {# {
]
+ |1 k( \3 a2 Q. E# y% }, [6 V" j. U* c3 P+ W7 d5 f! f6 R
turtles-own
) a5 Z" ~$ r% ]. A( [& H0 C6 T[3 s9 s! n" {9 O
  speed     ;; the speed of the turtle
/ O7 ^! l0 ^( n% ^& D) E  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 a3 \# B$ \" |4 @, ^, P  Y
  wait-time ;; the amount of time since the last time a turtle has moved1 o2 s( r2 _1 Q
]( x# J; D6 L. k& d

. e; S5 Z9 ^7 k( e0 V+ e0 ]4 epatches-own. Z- t; b: ^! [1 C3 o9 n
[
* d1 z% K# z* b  intersection?   ;; true if the patch is at the intersection of two roads3 l7 Y) Y  L$ l( r7 p+ @" W- M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 C9 D& R% [) }( ~" f                  ;; false for a non-intersection patches.
7 J! y) A# v8 c" E) ^. E  my-row          ;; the row of the intersection counting from the upper left corner of the9 }* l9 Y; w- L3 Y- @
                  ;; world.  -1 for non-intersection patches.
, G6 b! g. e& P- o3 ?4 e  i  my-column       ;; the column of the intersection counting from the upper left corner of the4 L2 X! K, |3 j% Z
                  ;; world.  -1 for non-intersection patches.- U& ]3 `1 x3 [
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 \4 J: z& K% u( \
  auto?           ;; whether or not this intersection will switch automatically.- X4 y2 }4 a1 G
                  ;; false for non-intersection patches., R0 ]% E7 i% p' |1 n9 s
]
- P, k6 \0 d# ?5 t1 C7 X/ d
9 q8 y" h' Z) Z2 O( ~1 z% t
' k; Z) \; ]* k; v+ D- x;;;;;;;;;;;;;;;;;;;;;;, F0 `  H/ G3 E6 T6 F
;; Setup Procedures ;;1 ^& @& H' D: x# G
;;;;;;;;;;;;;;;;;;;;;;
3 T$ d4 B4 s% l, R' a9 d; C" S: }, Q
;; Initialize the display by giving the global and patch variables initial values.) C( D  H8 C2 H- ^8 U2 R) s4 q
;; Create num-cars of turtles if there are enough road patches for one turtle to
/ O5 F' [  |2 z8 V;; be created per road patch. Set up the plots.
6 l  `8 ^0 y$ V1 J0 y8 }to setup7 l& }, w6 B5 U$ w: N! A& Y
  ca
4 [. ~, x' `; W2 u  setup-globals# Q5 Q4 I/ Y: \6 |# G) _
+ c* [4 A8 D: c, `
  ;; First we ask the patches to draw themselves and set up a few variables  g% [4 m" [9 |" X4 l4 U. W5 D8 E' x
  setup-patches
+ X. ]9 N* o# b) \. q+ s+ I7 ?  make-current one-of intersections4 x5 v: |8 m+ w. A; L/ B& B
  label-current- N0 x: P. {& S

1 V- @4 b" b) N0 {7 N0 j/ t  set-default-shape turtles "car"
3 T/ q2 z1 T, F/ h+ B# L9 D# F& W' u/ r+ n3 i) X7 x7 U- K/ l0 x+ ^" |
  if (num-cars > count roads)
! k. ?+ H; j5 ~  B! ?, s1 l9 S& l9 b  [
) I" K9 X1 k) J7 o    user-message (word "There are too many cars for the amount of "
. ]# R& H& z- Q1 F                       "road.  Either increase the amount of roads "
4 O2 W+ q* N1 f; P, s: s' S0 ^& N                       "by increasing the GRID-SIZE-X or "
8 g+ S1 q, e1 w9 X" `2 R$ b8 `% I. p                       "GRID-SIZE-Y sliders, or decrease the "
' o( @3 s% m0 U                       "number of cars by lowering the NUMBER slider.\n"4 C! Y( O0 G9 I: {& D
                       "The setup has stopped.")
* N9 L; o6 H$ q1 N  W    stop
3 S9 y: i( N5 N& Z1 s  v  ]1 c* U$ |8 e4 b4 r2 R+ w
2 _; L" y& D# {& t
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 \  k1 {' B$ d  crt num-cars0 J0 @( c+ C: S! q7 ^' s
  [
( u4 l0 H9 m. P( P% I    setup-cars
" s+ k7 A' _! ^. ~    set-car-color' t/ F' n5 j2 F3 ~
    record-data3 B) ]7 ?( X. }
  ], p4 W# ]' D( J. A% _% b
9 R) C2 P  d- g) Z/ Y
  ;; give the turtles an initial speed/ t# m! D$ C7 n# D( d
  ask turtles [ set-car-speed ]
" H9 Y3 w# f( O( E- u. i! u) A" K& }
  reset-ticks5 Q; s& w2 @' a2 O
end
8 x, e/ G% x, G/ J
4 j8 ~+ a2 C) Z9 f, v) g( X  E  r0 l;; Initialize the global variables to appropriate values
$ x3 H, {% ~6 c* b! w! Yto setup-globals
5 X$ y9 d; T: k& t- E  set current-light nobody ;; just for now, since there are no lights yet
0 e# b! o; K, {0 U+ a/ x  set phase 0
  I) j7 H* G7 H( y+ c" }# L! [; _  set num-cars-stopped 0
' {  g! @3 r. g8 f  set grid-x-inc world-width / grid-size-x$ I- ^6 C) P! V
  set grid-y-inc world-height / grid-size-y
- K" S' w, b; O( D) \$ R' R4 N; W; |2 \9 y6 O
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 d0 g3 b6 x% {% p  set acceleration 0.099, p8 |8 K! P. m/ b+ h- n
end
7 y5 l$ Y; l2 I: z/ [
" d2 J7 T" P$ |# S/ \7 T" f4 `;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# l& Y; a- T% C% \& z+ `) d8 m1 N8 Q;; and initialize the traffic lights to one setting5 L- Y( S; R! q1 V6 L) l7 b* L7 n
to setup-patches
! T1 U$ [1 l$ M3 r2 C9 \+ Q6 k. l6 A  ;; initialize the patch-owned variables and color the patches to a base-color% h5 u, c* f, H( w1 q1 P
  ask patches
! z) H8 ^6 ]; ~6 P) n  [
+ j+ h' J; @* x( M# ~    set intersection? false
$ b7 T' o* m' D3 G2 L6 A4 g* g    set auto? false% g/ k% W. y/ B
    set green-light-up? true( y9 |8 j# d& ~- |6 |
    set my-row -1
6 |' c- u' R6 Y# g7 F0 Q    set my-column -1
5 n6 ^! {; G  v$ ^. H    set my-phase -1
1 f' t2 u& W/ H/ n9 u1 h1 T+ }    set pcolor brown + 3
; o) F  T( K" ]3 {; O7 ]; ~8 s* P4 P  ]
) v8 H$ p: m  v. h* K
* C% l( o; p* @4 V2 \  ;; initialize the global variables that hold patch agentsets9 Y, U+ B( i. d; g7 I1 v  ~; L4 y
  set roads patches with
5 O2 ^, x$ I! z2 c2 F+ S$ L$ x9 `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  F. U$ L; d, S1 R% L/ y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% h% _# X/ X! o  W- K* q" R  set intersections roads with
4 \- M7 h6 M! Y* l  E9 k! B    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% m% @- m! [0 C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" c0 J9 ~/ T' W$ w  S6 D: d2 i( _2 u
" @$ t$ Y$ b1 d, C6 U) S
  ask roads [ set pcolor white ]
" F0 o" A5 b# t5 P% c+ M' R2 p    setup-intersections  `$ h0 w& T/ |' r$ {9 J
end, x8 b5 E/ W$ }/ Q* w( y
其中定义道路的句子,如下所示,是什么意思啊?
8 F6 E( [# G) E2 g set roads patches with
3 |% Y1 E- x& a. l+ O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) h6 k- r; `- L8 v9 n7 Q/ ~( A; m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 f4 R! D% u$ G& v/ l- ?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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