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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。
# p# r: \) p' _# r9 P9 ]; Bnetlogo自带的social science--traffic grid这一例子当中,
+ u) d2 k9 ~  C4 ?! |: Z/ r6 R( A+ \globals# Z' s, _- Z- j9 A  s
[& Z$ p% k: T$ a' h
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ j6 h" H7 f. r+ o; c  grid-y-inc               ;; the amount of patches in between two roads in the y direction  \, }& u6 `) q; m8 F) r+ x# M# Y) W
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& q0 |- l! N, Z9 F: ?! Y: Q+ v
                           ;; it is to accelerate or decelerate, }% i/ D; W4 N
  phase                    ;; keeps track of the phase8 P. k9 _) ?0 `; k' H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
& U2 ]- c4 E6 ~  current-light            ;; the currently selected light7 n7 x0 }3 G- }& L. f' F

2 y+ s4 n$ Y, l$ W+ c  ;; patch agentsets5 z+ j6 c1 \7 B0 O0 J! C
  intersections ;; agentset containing the patches that are intersections
8 j; ~0 ~( D, f1 @* h  roads         ;; agentset containing the patches that are roads
) e7 Q  K2 d( i5 p0 g- A2 o]) y' a4 M) C+ m& d) u

6 k, r5 j1 L/ T- `& a8 s; wturtles-own
; h) @! j9 L( P0 w7 P- k[
" v, m+ u5 B- n* L  speed     ;; the speed of the turtle
7 j1 w1 |3 w2 ~2 S7 h  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" z4 _6 l" R# l; b" T$ R* N6 S4 g
  wait-time ;; the amount of time since the last time a turtle has moved
: E) l# @0 Q. g" N% W$ U$ D]
0 I/ X& N6 V7 X) w- L1 ]0 Y% ^4 ], d; [+ q
patches-own
) A) l0 u, [- W7 W; F: C- Z2 P[( I0 n) I3 {: r3 r
  intersection?   ;; true if the patch is at the intersection of two roads
+ K1 M8 R6 U, G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 {/ q( H2 O( C; r! W, h% x
                  ;; false for a non-intersection patches.9 V4 {6 S& S; Q2 w; g
  my-row          ;; the row of the intersection counting from the upper left corner of the# R. ~8 X8 q4 d# V# {3 v, |0 F
                  ;; world.  -1 for non-intersection patches.! c( o! _  h4 b5 H; \' h4 t
  my-column       ;; the column of the intersection counting from the upper left corner of the
% U4 E% i4 D- B5 m                  ;; world.  -1 for non-intersection patches.
- z4 `# |' N, d  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 j' N) q. x. J1 _  auto?           ;; whether or not this intersection will switch automatically.
. {4 R' U; r8 s8 R                  ;; false for non-intersection patches.
* a; r% R9 l1 g) X" D]
& O- t& W6 J4 a1 ~
- I8 n7 d' D/ V. [2 q' U# ^  \) j# x
;;;;;;;;;;;;;;;;;;;;;;2 a5 Y. {  i+ a/ i4 D, p
;; Setup Procedures ;;6 w/ Z1 s- @% ]6 o8 o; P
;;;;;;;;;;;;;;;;;;;;;;
' @+ H& d# ]( o; q( l$ n% x8 \1 `8 \: D. V9 l) X: t
;; Initialize the display by giving the global and patch variables initial values.
9 O% S$ L. _) |1 [" R' v;; Create num-cars of turtles if there are enough road patches for one turtle to
. W# {1 A& X5 u. F' c0 d; g;; be created per road patch. Set up the plots.
) y2 H* E. A) |" P+ {- f  [6 L" c& nto setup0 v4 M/ T+ G! @* Y# W- ~
  ca
7 a9 g! c2 |, J% g9 ~" }  setup-globals1 l: f( @% L4 j- a) C. p

, x( F6 i5 D1 Q/ X4 O; n  ;; First we ask the patches to draw themselves and set up a few variables
; N! v9 r: ?$ L9 o* ]  setup-patches
; d% s: V0 Y" Z5 G. C  make-current one-of intersections. I! }9 l4 t  {- ]1 G! i% F
  label-current/ e/ _6 e$ G, A& Y3 U, h
3 d3 T  ~) |) X: L0 e1 j: i
  set-default-shape turtles "car"
& Z6 }& I/ N# Q: N5 b3 g- c3 i  O. S% _) Y2 U3 n" R6 h
  if (num-cars > count roads)
6 X6 D9 h) B; t  [
& m% O8 H  O( q/ I    user-message (word "There are too many cars for the amount of "
3 ~& Q6 @3 m2 H) ~9 s! e                       "road.  Either increase the amount of roads "9 O3 C2 z; e1 h9 I8 P" ?
                       "by increasing the GRID-SIZE-X or "2 J* W4 K; p  P  w
                       "GRID-SIZE-Y sliders, or decrease the "
* B* p0 Q# S, @( ~$ C4 ]- b                       "number of cars by lowering the NUMBER slider.\n"" i9 K' P0 F4 ~% W3 h4 l2 _. r
                       "The setup has stopped.")
( M2 U, d: E: y, A1 O- D, f3 h, S    stop* J% d5 C' O9 _, H* k8 O
  ]/ F7 F& l9 M* E7 e3 ?0 D8 E
' {8 b6 D9 j$ j8 M3 C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! G# h% U& M+ i# n' W# E
  crt num-cars
+ s4 H# t/ F  A$ H% o6 U  [
8 P" _* }/ |/ |& R; i2 x: Q1 F& D    setup-cars7 K' ?$ ]4 s$ c& [8 |
    set-car-color
$ |: v8 |2 R- m: ~" s    record-data
3 u) B* W; h9 {1 |$ A5 X  ]6 M) q7 l  g3 x4 H8 Y4 I7 K' V

9 {: U( H; ~2 x: z& `* I5 Q  ;; give the turtles an initial speed
0 w5 L+ c3 d! J- n9 J  ask turtles [ set-car-speed ]& J2 |0 N" C2 G; X
3 o) l8 m, |2 m" S4 T: I6 e
  reset-ticks3 J, Y& `! o! s# [8 G. p5 b' Y
end- g* G' m: s* {8 V. I2 @
5 o0 S: |( J) |
;; Initialize the global variables to appropriate values, A6 H- V( V4 W# T9 `
to setup-globals% q1 b" J- m9 I2 ~4 m3 I
  set current-light nobody ;; just for now, since there are no lights yet6 R/ e7 j" p* }4 A! T: k
  set phase 0
8 P" {8 C4 v' b( J  set num-cars-stopped 0: ]: R9 B4 Q% B6 |9 `
  set grid-x-inc world-width / grid-size-x) o; ^3 c/ z1 l: b. g+ `8 b
  set grid-y-inc world-height / grid-size-y
! S, B( G3 h6 p/ u' n
+ k' |1 M, C. P* m8 z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* S5 y! K7 @. g- T' I  q* \
  set acceleration 0.099
+ k" U: G* m6 p+ |( J6 E- cend
/ s8 G, K2 q6 u3 b: R
: U7 c) y% n4 d0 i2 t+ M3 G;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ R/ U! h* e+ K6 H& G: v( @;; and initialize the traffic lights to one setting/ C2 ^( Y" K- E1 o9 r2 j: J$ l% m
to setup-patches
, y8 S! [& X/ c) l; n/ r  ;; initialize the patch-owned variables and color the patches to a base-color% x; J# k, @2 x% Z) g0 j1 n
  ask patches$ H) {, H5 R2 h8 c5 a3 c* t
  [
7 x! ^, w* X) C  \0 @    set intersection? false/ x3 |; Z6 U8 c3 y( Y
    set auto? false
& v8 [5 M  ?6 Q# G    set green-light-up? true
5 M0 D' S( J! u0 v6 |  P    set my-row -1, }* a4 t  @7 E" S/ a
    set my-column -1
0 s8 P" @) G- W( C1 S& N% x    set my-phase -1( d4 ?! o% C# L
    set pcolor brown + 3
7 U0 i6 W& g( R$ e% o7 v  ]4 n2 V) q  h7 Y: G
( \2 Z. Z  s2 @
  ;; initialize the global variables that hold patch agentsets6 o* F9 B  a( z  y
  set roads patches with
. l9 y: V  y" D2 f+ P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ L# p$ w; Q: U8 ~, H& V* l9 d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ K; R8 h; J: b. H
  set intersections roads with$ `$ z( I* V; Q# B, K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and7 y1 b) C, q. w/ I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. J/ p+ z0 L) n
( ~* c: ~$ B8 ~& z* m  ask roads [ set pcolor white ]
! X" M: p; I4 t. k8 |% L. x    setup-intersections
1 X1 n# n" Q7 P- b9 eend0 O5 V) T( j2 W2 Q1 P
其中定义道路的句子,如下所示,是什么意思啊?
4 i; \) l7 S6 y set roads patches with
! w; I% W! t2 r- h" `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- D5 R8 R5 p- p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 }- n! W- r( H, X
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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