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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。' Z7 G% Q8 S' b4 e5 z* m; k
netlogo自带的social science--traffic grid这一例子当中,# k  T* x1 m  o
globals
( x4 b( j1 c' F8 [( Q! w[
# m7 C3 U! c0 J. a2 Z, T. ~4 K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. T/ g( h/ y1 K  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# O0 u+ |9 V% \9 ~$ i  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 F- Y4 M; }* U( }                           ;; it is to accelerate or decelerate" h# G, j" c- \( J$ g
  phase                    ;; keeps track of the phase5 k) S  U1 l& u1 ?" N$ A' e
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure7 K4 P7 g2 y, P1 x
  current-light            ;; the currently selected light  c8 E6 v, e$ A  @/ N5 }; i( k
- k, `7 a+ n+ V" ~& p6 ]5 O# S4 B
  ;; patch agentsets
3 K1 D" D" ^+ s, ]7 m  f, i  intersections ;; agentset containing the patches that are intersections
' n* u; D0 H, a$ V3 U/ d  roads         ;; agentset containing the patches that are roads
, ]: O- |1 v% H' l6 K+ b. @& \' _]5 I* z0 j! ~; _

1 }0 N0 i: d$ e& V$ }9 e8 vturtles-own
1 U' h* V1 O0 B0 X# [- v" k- X[
! D( e# [0 X( ^( \  speed     ;; the speed of the turtle
8 D8 H8 y4 B% G+ d  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: c6 S4 ?+ X" S0 N# }  wait-time ;; the amount of time since the last time a turtle has moved2 ~' ?8 h5 w: |+ d. W
]
0 k* d$ s8 v1 M+ {7 z
" Z3 v- ^3 d) \! ^patches-own# w7 V- e. i, l
[( p- ?. _$ y2 A
  intersection?   ;; true if the patch is at the intersection of two roads6 o( \/ X- b) Z' k. S9 x! \: s# Z! |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 l% X# G( Z# s* _                  ;; false for a non-intersection patches.
2 n, g& d& P2 P4 f! I5 d2 x( M  my-row          ;; the row of the intersection counting from the upper left corner of the5 q$ ]9 z: N8 g7 v& ]+ T
                  ;; world.  -1 for non-intersection patches.2 [+ q% q  Z. d/ Z) v
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 u' G' P5 X( H                  ;; world.  -1 for non-intersection patches.
' \6 S/ u9 m. g: r: b) Y0 J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 G0 D! X# {# i( x* Y; x
  auto?           ;; whether or not this intersection will switch automatically.! K( H9 N' S& ^9 N9 ?5 N
                  ;; false for non-intersection patches.9 K" n* \. w: J% ~8 y# Z
]
" k3 R3 [( f1 H- P. N3 V( U  L+ i8 k, q; G2 H7 y! g: P+ E

* w, U- O+ G$ T2 |% b;;;;;;;;;;;;;;;;;;;;;;  T6 r1 k- {: c2 V
;; Setup Procedures ;;
& J: |6 }; J: }2 I0 ~;;;;;;;;;;;;;;;;;;;;;;: h9 u2 W! G. l6 z' n0 D2 {

$ O* Y; H% F, A6 W# [;; Initialize the display by giving the global and patch variables initial values.( N& _) D; w( l
;; Create num-cars of turtles if there are enough road patches for one turtle to. v6 F3 o3 G& l0 p9 {$ F5 ?
;; be created per road patch. Set up the plots.
  Y! J7 t1 ^  @- @' oto setup
& Z. Q; i: U5 ?  |- X- F2 `1 e  ca- @8 p) z+ X( \+ F
  setup-globals
9 m) {! r7 `0 n! E2 ?+ T9 h& E: G+ t0 v
  ;; First we ask the patches to draw themselves and set up a few variables
; n  Z% f  b* J2 t0 o% {9 k  setup-patches: A; N0 F' L2 Y4 V. d
  make-current one-of intersections
4 q- V4 Z& f9 |( J- E  label-current* b% r+ [% q! D/ @9 Z4 H
/ m$ C/ G1 ~# ^; a: T( {1 N
  set-default-shape turtles "car". s% a# \) P2 D! h0 C3 o
" i3 O0 D1 K% q: Z: Y0 V" L; X+ z
  if (num-cars > count roads). r1 Z4 g7 c0 t; E3 x
  [6 _; p" E0 O4 m0 m& R. Z# ?
    user-message (word "There are too many cars for the amount of "6 y* b* u) B) X; x
                       "road.  Either increase the amount of roads "# Q4 l7 h% e: w7 v
                       "by increasing the GRID-SIZE-X or ". Y4 Z8 ~. B! ~9 r& r" J' [
                       "GRID-SIZE-Y sliders, or decrease the "
: j9 s$ i- O7 X                       "number of cars by lowering the NUMBER slider.\n"
* z. _% {! L) n7 x: I0 f                       "The setup has stopped.")
) f  z* _8 I, H) L2 K) X* L    stop
0 y7 U/ d5 x0 P  ]
# [, _+ z: a9 W$ W. w; {  o. [) d2 m
, s6 t! s' G# M' t5 T  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 b$ f  O' {( s* c% y9 j
  crt num-cars5 O' L8 T; ^' ~+ p+ B2 f% y* Y1 a, c
  [3 [+ v& l# k5 J4 G# f/ i
    setup-cars. ]: o2 L4 k# n" {! k
    set-car-color
1 M. Z1 s! r1 Y0 S( g3 U7 i    record-data
; j0 G1 \) n( k# E* m) k  ]( e1 f9 R: M$ j% f: E3 d  B8 }

' w3 M/ J: z# I4 H* z, ?) p  ;; give the turtles an initial speed3 F0 l3 a' [! V/ _) P% T# ^  N/ j, h
  ask turtles [ set-car-speed ]  n6 X  s: ]8 y! X6 k
8 e$ z2 ~5 r0 W- y8 S
  reset-ticks
$ k( y) V2 J4 T3 B# L$ T6 R0 Yend
9 b0 D, J( d* _  u9 I( S
; Q- \2 r6 Z5 Q) ^: a;; Initialize the global variables to appropriate values' V* [' Q7 o4 _  O+ j- Y
to setup-globals9 W, [& d' q; e7 i3 C$ ]& ]
  set current-light nobody ;; just for now, since there are no lights yet, a) ^6 Q( r8 N+ i/ }- l, G: h
  set phase 0& h6 f1 S1 B- G1 b
  set num-cars-stopped 0
8 i$ d. t9 j# s- o! }: t  set grid-x-inc world-width / grid-size-x
+ n+ O$ L2 f0 S  set grid-y-inc world-height / grid-size-y4 O! `# F/ k7 a" s. j

; \$ L. n$ ~0 H) ^* I- u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, a7 ?+ d8 ?2 [# p
  set acceleration 0.099' k5 ~! K. _$ M7 @
end
; Y9 d3 `% E  B/ P8 }! n4 [0 ?1 f" u0 I5 n
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 w. j5 d/ c- I( `! w# h& k;; and initialize the traffic lights to one setting
* T$ B$ L7 ?1 f) {; y0 Eto setup-patches" u) q0 z8 `# a/ c9 x/ n
  ;; initialize the patch-owned variables and color the patches to a base-color) [* t" t6 Q, f0 [4 O
  ask patches% [& K& G' S& t2 u. m$ j5 [
  [
) z- G% C: {7 x    set intersection? false- L7 x$ B9 o8 J1 `% `' `! i
    set auto? false
3 k2 u7 f1 I9 w    set green-light-up? true: M& _! H* S+ x; y3 q7 K
    set my-row -1
/ {& G2 b  J  f1 c1 i. m    set my-column -1
+ [) q) x7 v; u+ e- }' k8 U6 p3 K2 \    set my-phase -12 U# M9 N# S/ p- u
    set pcolor brown + 3
  o5 `5 J5 B$ s; V  ]  x( O1 B, {$ q6 ^- V' w3 ~2 n

( n5 s3 D$ u1 R0 J2 V, [3 H  A  ;; initialize the global variables that hold patch agentsets0 P- v) L) v! x% |
  set roads patches with
- v7 j2 Q- c0 s/ \* U) w* F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# H6 k: p: _; M1 n+ p# s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 `2 a9 c+ h2 D$ y  set intersections roads with) N' u6 N/ F( Q" t) s: c. D* G' M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) d! M" M: i' W2 s" ~8 r1 |8 T! G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 x( g4 W( q9 ~6 D/ Z

* ?- ~# ~/ r- J  ask roads [ set pcolor white ]" R6 W7 g7 d6 v
    setup-intersections$ ?4 J8 H4 @2 n$ `
end! ]* G( T. |3 p1 G, L' v
其中定义道路的句子,如下所示,是什么意思啊?! R2 e  v+ p/ s! q  _9 V" B
set roads patches with
9 W/ @- ], S5 s1 p) S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) q+ c  f& T) u! [- U1 D3 J2 \; Z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 t' b! D. h  n; y! L% R4 A4 y9 R
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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