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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。* C8 `! S! C' w- ?/ Z  j
netlogo自带的social science--traffic grid这一例子当中,8 C0 x/ e* u2 C7 U/ R1 t
globals
  H) x( ]3 {9 {9 }2 g% x[$ e0 Z# h+ I2 D
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) O! ~/ c+ X# z& f$ D, P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ N4 z3 E" H3 v+ E' N4 Z4 g
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, T# u" A6 v5 S6 |
                           ;; it is to accelerate or decelerate
. s  a' Z( U) q: m/ J0 p  phase                    ;; keeps track of the phase
& ?: o" K4 K- O0 y3 K" f9 b9 o3 G  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( M- T9 |8 h6 R& p* ?  current-light            ;; the currently selected light
) t6 |2 U) C* y6 b1 ~+ T# o' g4 [- k# o7 y8 }4 c" b+ w9 I
  ;; patch agentsets
/ ^: b9 ?! ^8 b0 c$ E& f, @  intersections ;; agentset containing the patches that are intersections
. g, v3 k( a: q) Q! J" X" g6 H  roads         ;; agentset containing the patches that are roads/ m2 B& p" l# m% b
]
/ \4 g, \; q8 X
% }! S$ T( B- \! r$ v/ [7 }7 s: `turtles-own
$ }; @1 T' x* v[% F) z* r- h/ F! X# v; g
  speed     ;; the speed of the turtle9 f& j, ]) x4 ^1 W0 F
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( ~/ \/ ?% x3 d( o/ o
  wait-time ;; the amount of time since the last time a turtle has moved
* r. o3 s3 R0 j6 s$ m]
) [  r- C$ N# c: `+ k$ a/ ?1 L$ |6 f
patches-own
5 ^/ {/ S, c/ |2 {! N6 u5 i[
' \8 h4 A$ W* B! M0 E& h/ _' l  intersection?   ;; true if the patch is at the intersection of two roads
. S0 u9 s, L6 H; W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. Z: i3 K& @& F: n4 V+ |                  ;; false for a non-intersection patches.+ K; H5 w. M0 v! j
  my-row          ;; the row of the intersection counting from the upper left corner of the5 @. n" y3 y4 v& e
                  ;; world.  -1 for non-intersection patches.
& ]6 j  k9 p1 Y, d) l$ ]" C. q  my-column       ;; the column of the intersection counting from the upper left corner of the
$ k0 }0 _* _: J, t                  ;; world.  -1 for non-intersection patches.# Q& i' w7 P4 _5 F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 `5 F& J9 w. c: t$ u" ]
  auto?           ;; whether or not this intersection will switch automatically.$ N- E/ s: v2 R! {
                  ;; false for non-intersection patches.
+ v! W2 s5 T, i4 _' r3 ]* T]& G* R) V  Y! @' |) B  ]

9 ^! b- b7 m8 z/ L5 w* ]$ X; k: r
;;;;;;;;;;;;;;;;;;;;;;. T9 Y7 @7 n) I
;; Setup Procedures ;;
* [9 g  L7 I: P& u2 K) k;;;;;;;;;;;;;;;;;;;;;;
4 l" q1 D0 A3 t! J( k. z
0 K. M6 y0 }# [0 C3 G;; Initialize the display by giving the global and patch variables initial values.
% }+ L4 u6 ~. O8 }9 V0 t: J;; Create num-cars of turtles if there are enough road patches for one turtle to
% C. K$ g8 n, |' H" M; c;; be created per road patch. Set up the plots., G. a: ?8 M) ~/ M' A# i3 b0 Y
to setup
' k/ X4 Q& a" C7 {$ |  ca
' x( j; K- e( B! b9 @( I  setup-globals
' R$ ]. w8 _2 E
: [0 @  p) `1 {  ;; First we ask the patches to draw themselves and set up a few variables
$ o# Y0 {7 v8 [( q1 M  setup-patches5 x- O% v/ a$ H+ Q1 x* Y
  make-current one-of intersections
, L) B  I' C. ~5 X  label-current
* u$ b2 ?* F* O2 F/ r1 `
% H5 B" V) k- P0 I/ w5 k5 @  set-default-shape turtles "car"
2 b! D. U& A7 w, ?* t+ `& g6 d; Y' X. T4 M6 w) _& Z
  if (num-cars > count roads)# \, D9 k: J& H: f& b3 a
  [! h% w( ?) l' t& K/ g4 B$ A) \# D
    user-message (word "There are too many cars for the amount of "
6 P6 G2 \  v7 r/ {' n, ^( N- C# |- v                       "road.  Either increase the amount of roads "
( W9 m0 a6 O$ l7 j, ^$ J                       "by increasing the GRID-SIZE-X or "
. C# c$ [! `+ `- F# U$ i4 m1 Y                       "GRID-SIZE-Y sliders, or decrease the "
+ f3 U3 E1 c9 r# U6 l- K                       "number of cars by lowering the NUMBER slider.\n"+ [) B9 g1 F% C5 _" n  J
                       "The setup has stopped.")
! h0 s; C* c/ V  J$ W4 c    stop7 J" ~) E8 j9 @0 i  W  R
  ]
% H+ O! [. t$ f) N% ^4 R% M
( U. @6 l' ~9 M, |  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- _) o$ d8 c& q1 m+ ^+ F+ j+ U. ]( H  crt num-cars
  X5 m; b6 |( t  [
1 G% X7 Y0 A4 T/ ]: ]2 ^6 {  x3 [    setup-cars
9 v/ X/ w. P; H4 e1 M- b    set-car-color
/ Z2 L* I7 T- T0 ]) K. g    record-data
5 X/ d4 P1 ~) ^0 }- S  ]
' @. E, J; `- J8 X) m' O( G
- [' L- b' c) p% [  ;; give the turtles an initial speed
! E) S/ Y8 m1 d  ask turtles [ set-car-speed ]: P( N, O( u+ j/ `& c
9 I% n" ^/ E6 e( p
  reset-ticks
5 K: U0 e7 C! l( F& O( V% t" P; Gend! b: j: _, _0 U/ L5 C
0 E; Y% d* A$ z5 @& R8 m$ s3 I
;; Initialize the global variables to appropriate values( k+ p# F$ j: D  V9 ]5 J4 \$ Y
to setup-globals+ ~$ R" Y4 t! S! }$ \
  set current-light nobody ;; just for now, since there are no lights yet
; e: L8 v" L& L: h- Q  S  set phase 00 _! D6 c5 k% C& {3 Y% T  a
  set num-cars-stopped 0- r8 d4 _: U! D5 B, q1 i( ^
  set grid-x-inc world-width / grid-size-x
0 R/ t7 Q  a! }4 Z0 P  set grid-y-inc world-height / grid-size-y# O. v/ J& @  G# P  W+ A

$ U& H5 T! X! m# [$ V  a- Y8 R  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ K2 V! j4 W2 _  set acceleration 0.099) U3 @  r4 A. J6 L) _
end
$ |, ?  g2 N+ c1 N/ a' d
0 c& F" K  _) P% e  B. c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 v0 S; P- c8 C: q. T) k( k9 v" N
;; and initialize the traffic lights to one setting* y1 }# e' a' O- o* M( T  n
to setup-patches
* i/ f! g4 }" }$ f' J  ;; initialize the patch-owned variables and color the patches to a base-color+ [8 f0 s, B& Q" m0 W5 u1 C3 j
  ask patches
# y; o0 @7 W1 J" T  [2 o. l! z5 `& Q5 b
    set intersection? false* e: Y/ `2 c  l; U- K7 q! v
    set auto? false1 i: N. u8 I$ d' \
    set green-light-up? true8 q" O6 u/ m, @& o2 J/ I
    set my-row -1
+ }  `' J1 X8 S* C' B4 U! z5 ^    set my-column -1
. q; F( ~4 F% R+ P: X7 F    set my-phase -14 N3 d: i2 U: {4 P! |" e  I
    set pcolor brown + 3
& m( p7 b' d4 S" |- G. j  ]
6 V7 Y3 H" |) V. T
0 _2 v7 E0 {' L$ \$ v  |' b8 H$ t  ;; initialize the global variables that hold patch agentsets# m6 {5 c3 p7 h3 V* t! w9 X, l
  set roads patches with
$ U# c- h9 n3 w( ^- z* ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 r# }- L. P* ]2 ?0 o3 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  U3 `1 O& T( K, e8 k  set intersections roads with
" q# Z- H( O9 Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 j8 |9 w7 w! L3 ?7 E" q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. s! l6 o/ f9 {" {" a1 B) U9 Y0 c
+ n& m5 V7 C. m7 T; B
  ask roads [ set pcolor white ]
: v' g) a8 \1 [3 c8 G, x! h    setup-intersections! J# Q- D. {  U
end  c* a9 @3 e0 q1 F( @
其中定义道路的句子,如下所示,是什么意思啊?
; |4 x9 ]3 f  q9 s% S/ T* t- S set roads patches with
0 ^5 v1 U- k9 n; H6 `* Q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 K2 _6 m% L4 F2 R( D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 d$ ^# R1 r$ r! o5 f2 L6 [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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