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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。
! b5 E! f4 u7 Y$ S1 Gnetlogo自带的social science--traffic grid这一例子当中,
- S. n& U+ b, J9 qglobals
( ?; N! p) M" ?' i- |2 s8 S+ q& G[
$ y3 k/ p9 F( c  grid-x-inc               ;; the amount of patches in between two roads in the x direction6 [( i: ]" A' _, |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction; n3 F+ x' K8 q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 h% C  l/ d! Q4 Y  u                           ;; it is to accelerate or decelerate
! Z* [% I" Z9 s5 N  phase                    ;; keeps track of the phase% T4 s+ r9 B* {4 M
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 B+ J7 q  R: Q5 z( i
  current-light            ;; the currently selected light
0 }/ o5 o! A2 K+ a# ^! U4 L7 o0 U# b  }+ x7 x( |2 S# O
  ;; patch agentsets" t- `0 z' t8 H( d9 a" Z
  intersections ;; agentset containing the patches that are intersections
: F9 V/ t/ g; d: }  roads         ;; agentset containing the patches that are roads1 h( V2 R( d5 f: D# b- s; v
]4 e$ Y3 x6 J% @- ?6 R; ?

* [% t0 J# H. kturtles-own
& F" v6 m9 v0 B3 g[0 X* t1 M! ?9 b
  speed     ;; the speed of the turtle
; t7 z8 n0 j5 [  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 D0 f- ~/ O/ n9 B8 _' l
  wait-time ;; the amount of time since the last time a turtle has moved
1 u( \8 u+ b1 K. H) J% h]0 _! n1 r/ j5 ?& s
8 a8 e9 N/ p8 @* y$ ~2 ^
patches-own% T' t) Y5 \: s# ]; K
[
( e/ U) T& E- b  p% W  intersection?   ;; true if the patch is at the intersection of two roads
; x1 _5 }& x7 Y. j& M$ @* G  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: t4 P9 e9 S8 J- P! K) h
                  ;; false for a non-intersection patches.
! }+ Q% z0 K. m# Q  my-row          ;; the row of the intersection counting from the upper left corner of the
. ~  z' ]* V. S% C* }                  ;; world.  -1 for non-intersection patches.+ \& Z: I* t  ]: L) ]  \' ~0 X: q
  my-column       ;; the column of the intersection counting from the upper left corner of the
' {* B1 M! L3 S5 r* x. A4 F                  ;; world.  -1 for non-intersection patches.
: E7 \( l! _% y5 o4 R1 p5 Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
+ j: ~: {* n& z  s% O  auto?           ;; whether or not this intersection will switch automatically.
4 J" J8 P# b% x+ P3 l                  ;; false for non-intersection patches.
- V2 D; ]7 M$ M" T8 T. C3 w]! ~& a; m( b& k

+ D! g- U" f. ]7 C$ _" K2 g" M  a: p5 p6 c3 S' [1 w
;;;;;;;;;;;;;;;;;;;;;;
+ z9 M3 ~* D1 g$ \4 b  A8 V! Q0 o;; Setup Procedures ;;
* N' I; c/ {/ d! b* D8 A  U: y;;;;;;;;;;;;;;;;;;;;;;
* o* }% T' c  W) d  B  K3 O; p0 T# ?8 T9 o9 z. B
;; Initialize the display by giving the global and patch variables initial values., g- J# L" U' v! p
;; Create num-cars of turtles if there are enough road patches for one turtle to5 @; i  N1 s# G/ ]. \' }, f& m$ Y
;; be created per road patch. Set up the plots.
) p0 i- G. ~' C* I7 zto setup5 d" S! ~2 S1 Q3 P
  ca
0 `/ U5 \$ H% l/ e2 L- C* N  setup-globals
+ ]3 @; `. A( q+ {6 v" w9 z
* l  h* C# l2 n" k3 R/ d  ;; First we ask the patches to draw themselves and set up a few variables) I4 F! H6 C! A1 K8 h
  setup-patches% a9 ^& o8 y1 m6 h% W2 I8 Z( A
  make-current one-of intersections
$ G9 t, |6 s+ ^$ `' A6 ]& A  label-current% f7 Z9 V" G5 g0 Z( E" S
' _1 D$ @3 C3 {! J. W. P# t
  set-default-shape turtles "car"" f% Z( E# D3 M; U- X4 |' h

+ \1 s' ^! H3 n( J# {5 P' |  if (num-cars > count roads)0 Y  W9 b0 R; f, L) V4 E
  [
5 m, i3 ~9 d& y8 |1 ?' S6 t5 `# O# V1 t    user-message (word "There are too many cars for the amount of ". H5 N& T% r3 d* J: `
                       "road.  Either increase the amount of roads "- ~+ a5 _/ f8 G$ d8 q/ p: ?6 Y% k
                       "by increasing the GRID-SIZE-X or "
5 P' M, d% `1 |8 V8 s  @. |* {3 R1 e                       "GRID-SIZE-Y sliders, or decrease the "
+ A" a$ o' |( w, |/ m                       "number of cars by lowering the NUMBER slider.\n"
* O' e" c7 A% e8 z                       "The setup has stopped.")' C) |* a* l6 _' ^7 x
    stop9 n. A4 ]5 c% T
  ]& _/ w" G: t( j: S) d

1 j5 T. t* t  L4 b  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 |5 f; |9 a+ }9 g* d" c* R3 [
  crt num-cars: i* T. o- M, F# ]4 {, W+ h- z
  [. X; r. E! ^; a2 m, C  h
    setup-cars
! T2 s$ i6 a. F( F/ Q# u- W    set-car-color7 ]  E% @& f! \. I: r
    record-data
0 B+ J0 o8 u: g9 f* V8 b! t) Q  ]7 y. n7 T6 W: X% o+ J

8 N' a* t) w2 g2 b/ U& T  ;; give the turtles an initial speed) U% y4 a; D6 Z2 p/ e5 k8 h0 i2 u
  ask turtles [ set-car-speed ]
# ~6 p5 P! j5 T! X) c* t
  |3 w3 Q# b- ]4 w+ f1 {  reset-ticks6 c$ z+ U. Y* p+ T8 g6 T6 D  Q1 D% T
end. B, ]' M: G' ^& Y& P
7 l* O# o1 B# w0 U+ C. [& G
;; Initialize the global variables to appropriate values; c8 d) F) H1 k, \" [. r
to setup-globals0 k9 f& [8 ~# _9 z
  set current-light nobody ;; just for now, since there are no lights yet
: F  T2 K9 V5 e  set phase 0. U. b4 L7 y$ G" I. s3 m# l
  set num-cars-stopped 05 l8 d0 n- f8 s. D6 x
  set grid-x-inc world-width / grid-size-x# p4 }+ r2 {7 s/ h! X" p. ]. p
  set grid-y-inc world-height / grid-size-y! D3 q7 f  Y! [4 F+ X; N
- P+ z9 @' t6 Z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) G3 t2 l4 v! |, B& e  set acceleration 0.099+ y, h" c1 U1 B
end
. m2 f! t. \. Z, I. {) L" b( [/ e( P# @- U7 ^3 w2 S8 K% `* L8 S
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 Q2 w- E5 r- \% ^9 i9 ~+ \;; and initialize the traffic lights to one setting
4 v9 v0 m8 b! S$ r' ?4 E! mto setup-patches6 T4 W& @, Y: j# T  o8 Z
  ;; initialize the patch-owned variables and color the patches to a base-color2 |" [2 u" _( X% M+ f
  ask patches+ T7 t; `8 L% I% V& Y: H
  [# m' k" m, U! w9 h1 V6 K
    set intersection? false
2 ?, X5 ^3 A, j' c    set auto? false
# F- T3 J8 c' _& K) U  n    set green-light-up? true
, ^. P7 e6 _& o5 L    set my-row -1/ T' V* p3 j! A
    set my-column -1: d+ Y+ g% }& m- O4 _2 R+ O
    set my-phase -1
0 F; L/ t5 C: o    set pcolor brown + 3
& `7 B) A, g1 P: u4 J* w" g  ]9 }5 F0 N0 V  V# ?

+ j' T( I" d/ M. O$ G8 ~  ;; initialize the global variables that hold patch agentsets
; H/ F3 s* d; Q3 |. g  set roads patches with, B' w; s5 k6 |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ o6 h& ?  f! I1 f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' u; l, A7 P& ^  set intersections roads with
2 a8 q/ M8 G' d- y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- `$ ]1 p- a: \( U# X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  M# J( X4 }( t$ Y- |* S

; r5 x+ f: E8 D9 K) M7 t: B  ask roads [ set pcolor white ]  t( l; X4 D& M
    setup-intersections" u5 z5 U0 ]: W. o- H& N! \
end
7 x) I4 i3 {2 o# l1 E- b其中定义道路的句子,如下所示,是什么意思啊?4 L' {( ]) R7 ~/ L+ m# U( B, T
set roads patches with
" ^7 a5 \" x& Q6 N% x) D  y( P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ z& }* T, S0 I2 x& h7 O, \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) c# {# k) R+ }3 A; 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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