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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。* \1 m2 O- ~; z1 O
netlogo自带的social science--traffic grid这一例子当中,. e  E! J7 u) J* I+ m
globals8 s8 q' a- R* j2 R' W( U  a4 Q5 ?
[  F8 x* A+ t& p6 o9 @! D5 Y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 Z8 W, z/ A4 j0 h' v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 K0 N. b/ o$ F5 O  acceleration             ;; the constant that controls how much a car speeds up or slows down by if! Z3 m  l* k& Q! n; i* g3 T) o' ]
                           ;; it is to accelerate or decelerate
1 c& Q/ J9 D* s  phase                    ;; keeps track of the phase
! J" o; b# Q/ u6 ?/ a9 G  `- g7 N  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 G7 q* V( q7 Q$ a4 K2 s! I5 V
  current-light            ;; the currently selected light4 U2 ]8 @7 \' I: T7 r0 R; y, t3 m
+ n8 H; V  B- d5 C" C# M+ t
  ;; patch agentsets0 S' U2 k! r4 z9 S& Q% y. ?! W
  intersections ;; agentset containing the patches that are intersections
4 V; Q6 m9 @# ~' y1 N: I8 l  roads         ;; agentset containing the patches that are roads
% B9 I/ R1 C3 \1 H0 h]
2 W4 ]+ n+ ~+ ^. M9 @% k% M
! [9 L! B/ t7 F0 W6 a6 vturtles-own9 Q  X. \; V5 k) n: d) m9 N( }
[
& P9 ^9 Q4 t* |7 K# m+ L7 M. o  speed     ;; the speed of the turtle
$ U, }% u% R& z- V  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" c# E, w9 W, a# M; E
  wait-time ;; the amount of time since the last time a turtle has moved
, I# E! h5 f( z5 o' c]6 I' m( k' r7 C) K, q/ k2 ^7 @

! H- V, B2 q, E6 c1 v6 n- @patches-own  M/ h) b& s/ @$ m( h! {3 W
[/ u& g9 x" q# d$ x7 }1 C3 T
  intersection?   ;; true if the patch is at the intersection of two roads
1 `: w9 w* p5 j: j. @+ i  green-light-up? ;; true if the green light is above the intersection.  otherwise, false., L, ^9 \+ J5 A) f% W# U: h9 r
                  ;; false for a non-intersection patches.
  n' ?1 b7 M. e# p  my-row          ;; the row of the intersection counting from the upper left corner of the
- @2 u% G, S. Z+ D# I& \& x                  ;; world.  -1 for non-intersection patches., L. f0 l: L% o0 L
  my-column       ;; the column of the intersection counting from the upper left corner of the2 s4 X9 m" Z4 P! B) `& z: ?
                  ;; world.  -1 for non-intersection patches.
: Z) d' R$ g# ?! Z6 E- g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: q9 i) p0 N5 Y9 E8 `, M! w  auto?           ;; whether or not this intersection will switch automatically.) c5 M" k2 T2 V; R- V, B, a
                  ;; false for non-intersection patches.
6 Y' O. O8 V0 L6 t7 M  D2 N]  O# t8 S3 H: H/ t0 r0 l
* n; m1 P2 F: G, x9 U/ F% B# c& e
+ B5 X. z2 g6 b% m3 n
;;;;;;;;;;;;;;;;;;;;;;3 J$ L2 v1 S9 c. A* e
;; Setup Procedures ;;/ C0 R  @- w3 I, X- v/ \* N9 p
;;;;;;;;;;;;;;;;;;;;;;
  e7 ^$ B8 q+ \4 `3 D
* C7 K0 F) S0 Y! l3 w;; Initialize the display by giving the global and patch variables initial values.
6 r) b2 ]8 C1 I( D9 U9 \;; Create num-cars of turtles if there are enough road patches for one turtle to0 l5 V+ T* O! v( k/ f
;; be created per road patch. Set up the plots.
3 m# U& r6 P3 j* X; nto setup  Y# ?7 W% Y. E
  ca
4 n' p3 i, }1 V" ~9 r. l& i  setup-globals
0 b$ @& P4 ~6 ]9 ^; I
5 S8 O8 b1 ]2 {( e: K: x3 @  ;; First we ask the patches to draw themselves and set up a few variables; i6 `7 S1 [9 |5 R4 a& a; \! {! o
  setup-patches
+ F' O( n, G9 J  make-current one-of intersections
% j. A) V% W. {9 M1 t  label-current% ?% ]: i8 G" f& l7 j8 {
+ c/ `3 P( _2 J3 `. w" {
  set-default-shape turtles "car"
0 a% m- j( e' x7 y- a/ T6 f! X1 F7 i4 I
  if (num-cars > count roads)2 \2 z, v( b: X3 _. R: s* B
  [
1 B5 c4 }7 `# e/ v; L+ d    user-message (word "There are too many cars for the amount of "/ x# J1 X8 y* ?
                       "road.  Either increase the amount of roads "" y: l5 q5 Z& Q3 |
                       "by increasing the GRID-SIZE-X or "/ T! t% g: ^) ?; k3 r
                       "GRID-SIZE-Y sliders, or decrease the ", ]# i8 M. n8 D, u% K+ y! ?
                       "number of cars by lowering the NUMBER slider.\n"
+ \7 K: D! f- b  r4 T                       "The setup has stopped.")
% }2 `4 w7 P- A/ v( O7 Q    stop+ u; s9 G1 @; `+ V
  ]1 {- }. T* {5 Q# n& M6 a9 j+ Q: }

" Y8 W1 u  \1 n  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; H" S8 A' s% n. _& P7 Z5 d  crt num-cars( Z. q( Y% k3 d; G# M' }6 f, l
  [4 s: J- |& O% l. B
    setup-cars
% V7 [9 V3 G. v3 w* }6 V( ^1 M0 B    set-car-color
) m4 m. W  c0 j! p    record-data2 F9 J1 l& j" G6 g  e
  ]: B3 b, F) @  b& E$ I+ j6 M
' f2 k# w) ]$ P2 i
  ;; give the turtles an initial speed# |+ r. ^, {: [  l
  ask turtles [ set-car-speed ]; o$ K! X8 F) _- v# h0 U

2 n6 w$ y& Y) q  reset-ticks
! Y! i+ Z+ k0 g* d: D6 wend7 _8 g' }$ n0 i8 t/ V4 S! i# M
' m6 n2 {/ p1 F. |( }3 p: b  }# B; S
;; Initialize the global variables to appropriate values2 j6 B- s7 b. _! g. q' X/ E
to setup-globals& w! j$ v$ \3 w9 a  U) l; v
  set current-light nobody ;; just for now, since there are no lights yet; L% p& g) G/ o6 w( Q, l
  set phase 0) K( K8 i/ i- l) ~6 G5 i
  set num-cars-stopped 0- G; ~/ E1 i) u! i1 V8 s6 Z
  set grid-x-inc world-width / grid-size-x8 u2 g. P' B. ]" |+ j0 L
  set grid-y-inc world-height / grid-size-y4 U. y) k. {7 u

9 G+ c) s6 _& x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 [8 ]0 B* A- |  set acceleration 0.099# s3 A0 e9 O2 o/ H
end+ i9 F% b9 M6 `
# N7 \7 c6 Z' s  m1 w6 R% B
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ p+ C) m( ]6 Y# m
;; and initialize the traffic lights to one setting
3 G6 x5 o# C/ {to setup-patches
7 E( k2 t+ z# O  }  ;; initialize the patch-owned variables and color the patches to a base-color, j4 {0 R) m$ `% |" P% K+ X* }
  ask patches$ s+ d8 }7 W9 r
  [
% w5 x. w1 S' M0 g+ `9 \7 p    set intersection? false
4 v0 m, P/ g$ f3 o5 |. b  _    set auto? false
7 z% h- d5 _6 |4 x* f    set green-light-up? true
) U! U8 D" u; _: F8 b* L8 |& ]    set my-row -1
  Q' b" i& ]1 t8 p4 M    set my-column -13 M$ f1 `3 F& f1 E0 F
    set my-phase -1& n) b! i- ?6 S. M
    set pcolor brown + 3
1 c. M* O% o, t  ]
6 v5 X6 x( |/ i3 I& s
: g7 C, |$ b- R5 H$ O  ;; initialize the global variables that hold patch agentsets7 U9 U/ d5 M% t
  set roads patches with+ V  @2 v+ C6 [6 ~% n' ?2 |" ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 p" t- M- \' n5 n! N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' v, k& [. Q6 \$ y
  set intersections roads with
; ~% f% |. @% m) s6 l( U6 t3 U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ Q4 e4 f# v) ^: p# v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 o2 S* A1 t0 n/ e( O6 |

* m& a3 u5 r6 P- O# O; y  ask roads [ set pcolor white ]; z6 V' N: v6 {: ]
    setup-intersections" \* |+ _+ n' [& R2 G, J
end
& o8 V! E; T& U% ?其中定义道路的句子,如下所示,是什么意思啊?5 I0 O2 W  Y" M* _. e. h, B4 B
set roads patches with" T' C; b7 ]2 s+ J& v/ v4 ^8 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 f; v, F* s9 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* I# ]$ ~3 I* E+ A
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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