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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。& m; F8 c0 G8 q1 n
netlogo自带的social science--traffic grid这一例子当中,
3 H& V- w) C& _6 h- ~globals; d  n; ^' G. j1 N) I  p
[
8 u7 D1 W/ G! W# q  grid-x-inc               ;; the amount of patches in between two roads in the x direction" A2 O7 a2 W( [8 a) ^
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' b! q2 a6 {" |5 j7 h" o1 V4 [. {( v
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  d* d5 E5 |' E( E) l. R6 C                           ;; it is to accelerate or decelerate6 w! e. {: I7 u) J* H6 \
  phase                    ;; keeps track of the phase% j2 ?4 X; K# i2 D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 I3 ?4 c- F* t1 c
  current-light            ;; the currently selected light
  n  @, q+ l& w2 ]( a1 v
8 y0 [0 ?& A& X$ e% \- A3 [  ;; patch agentsets  {& {( b, L" i( l" V
  intersections ;; agentset containing the patches that are intersections
" X) O- M4 u; }( J  roads         ;; agentset containing the patches that are roads
9 ^- q. t; g& v% z  @0 l. m* v0 m]3 k$ Q- U* k1 Y

9 D: x; A9 U. Rturtles-own4 v. Q0 r) P% D' X  K
[
+ L- |4 G# m* s, Z5 P4 ?8 v5 F  speed     ;; the speed of the turtle
2 F" E2 L9 K# G0 r1 @) v) |  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# B. P/ ]! l  c; p6 M
  wait-time ;; the amount of time since the last time a turtle has moved" D' t7 _0 y9 w9 Y0 u- W/ E& i2 d/ t
]) Y$ L7 c0 V) i/ T/ N7 W
2 d. z8 M4 g: }) O1 T3 k
patches-own
- C% [) ?" F! O1 N- T7 n[
. c- M' c1 h8 ~0 p3 x3 A2 C$ V. Z% z  intersection?   ;; true if the patch is at the intersection of two roads9 u0 I. t, ^0 y1 R0 L- l
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# Y" R& ~4 E) @; w2 l' h                  ;; false for a non-intersection patches.
# Q0 q$ k/ w0 d" w/ g! s3 b, D  my-row          ;; the row of the intersection counting from the upper left corner of the
# q( N7 W) L6 w0 d, U                  ;; world.  -1 for non-intersection patches.
" e: h3 Y( F  |/ }2 M; V  my-column       ;; the column of the intersection counting from the upper left corner of the9 D' }& c( v2 L3 B
                  ;; world.  -1 for non-intersection patches.* r( O5 V  h8 ^5 `4 O
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( {$ j: p# K4 t3 z0 w
  auto?           ;; whether or not this intersection will switch automatically.
1 Y  R. s+ g1 B3 \- C                  ;; false for non-intersection patches.- H) s2 J3 ^5 v+ m% M
]& {. @3 E' k) N3 p7 X! V3 W

$ ]: r$ N, A5 h7 C# B. N! g7 Z7 c, `8 L( Y: {' L
;;;;;;;;;;;;;;;;;;;;;;
4 d* P8 B( X8 Z2 O5 C7 i;; Setup Procedures ;;
. j# R- g* R/ Z3 |; w& L;;;;;;;;;;;;;;;;;;;;;;: H8 Q* }9 [/ X
- M- W# `2 k3 P6 l4 q5 ]. l* m! h
;; Initialize the display by giving the global and patch variables initial values.3 Q" f6 F, ^) V
;; Create num-cars of turtles if there are enough road patches for one turtle to- i* D* r+ u! E9 A# {, i
;; be created per road patch. Set up the plots.
. l& m/ `( e& @. A/ qto setup
% f+ q: t5 S- K/ _3 Z  ca$ ?3 L  ~1 \2 Z# k2 G. f* ]
  setup-globals
& t  |" F6 u1 I) E+ x  V
8 G( P. @; q4 l: Y, J  ;; First we ask the patches to draw themselves and set up a few variables
+ A' r, f( ~# d. [% D2 j( W% ]7 K  setup-patches. b# c9 i) E& D; M5 ^" C
  make-current one-of intersections" X/ O# }7 q5 ?7 o8 q9 [1 M
  label-current
! i8 c8 u7 |7 P
2 \  z! @' e7 ]! a* o+ |7 _  set-default-shape turtles "car"
* ~# U8 ^3 \7 s1 D/ w
9 ~  [0 d8 ~/ p+ Q  if (num-cars > count roads)
# m3 P( l# o# H: p, s, N2 @  [* n# p+ G; q! @  p! r2 ^7 k& W
    user-message (word "There are too many cars for the amount of "
# y8 h2 u$ |+ Z  A$ S5 t- v( K# ]                       "road.  Either increase the amount of roads "
* U9 j. l+ z2 j6 z                       "by increasing the GRID-SIZE-X or "! Y* \2 T8 k9 s1 j% }( P
                       "GRID-SIZE-Y sliders, or decrease the "+ p( s6 C# b% x1 N5 e* u
                       "number of cars by lowering the NUMBER slider.\n"
+ {! m7 l$ F& s# T                       "The setup has stopped.")! W/ e* T! `; @
    stop5 ~2 h1 M( i% a: @6 \7 Y
  ]$ M$ h+ I$ \, ?3 K+ t
9 c5 x: {7 p9 H% v/ V. r2 o
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 C% s4 y% t/ t) ]  crt num-cars  E# {7 ]- }7 K% _- K4 ]3 Q/ H
  [$ I8 h$ _3 q% L: z6 k, i
    setup-cars
. z. G! J4 X' F3 b    set-car-color
! Z/ H& r$ P( {) ~0 z- e# M    record-data% y5 B: R# @1 }$ H" I
  ]
& y- v4 J& [2 [9 `% h9 [% e" s4 V3 G" ~$ A
  ;; give the turtles an initial speed
8 E0 j# {  x# }; v! c  ask turtles [ set-car-speed ]
  w# f$ n, J) a/ `
$ L% g8 h, E5 g: f$ J: R  reset-ticks. Q+ l) z5 C5 Z
end
3 Y. Z+ Z3 B# }" ~' J) n+ R
; K; E) |" ^2 K* q$ G8 `+ \6 c* a;; Initialize the global variables to appropriate values
1 H9 N; a; D1 Nto setup-globals; b, |' n3 f! Q: R1 t: z1 Y
  set current-light nobody ;; just for now, since there are no lights yet
9 l4 F8 Q0 W4 r  set phase 0$ B) _2 |( M: b- d- O
  set num-cars-stopped 0
2 R4 h. b- Y2 c. v  set grid-x-inc world-width / grid-size-x
) G4 u, Y8 o; z8 a6 ?  set grid-y-inc world-height / grid-size-y
2 q& h4 l1 y8 M
' S& P0 Q4 F" K  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; ~8 M$ t- p! M+ T- X
  set acceleration 0.0996 K% f/ Z$ K, l( W
end* b0 z7 J2 q9 ]' w# w

+ }# L" S4 h# y) p# M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) A8 h( B1 g) T7 a- b8 T( m
;; and initialize the traffic lights to one setting5 |- |1 G$ p0 k+ k
to setup-patches5 R8 F, }( f, c$ A6 q/ Y( ?
  ;; initialize the patch-owned variables and color the patches to a base-color7 u$ a/ G- u; ^
  ask patches% y, e! {/ j6 W/ x( x
  [
2 O$ A, }4 k0 L9 `; l6 }    set intersection? false6 U* e5 Z$ x0 `2 d# X5 x: y- b
    set auto? false
& _5 ~5 J* d/ H" {    set green-light-up? true
- H3 u1 _& k/ q5 [3 \% B, J3 u    set my-row -1: n9 w: |" Z0 r% |! g2 P  [8 G% H
    set my-column -10 X. u3 ~* H# l
    set my-phase -1) o: l) T7 B1 c* ^; }/ M; i
    set pcolor brown + 3
$ T; ]( C# X0 O# I0 w. G  ]" V: c. I& ?2 Y- _2 o! x  K# W

3 q$ `/ w- o7 E; l( }! B  ;; initialize the global variables that hold patch agentsets7 ]4 [0 [4 X. j, L0 `! b
  set roads patches with
. e2 a3 f: {8 k' b) ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) M3 `5 m+ {* z5 Z' i! B8 v2 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# M8 m' \) D* K, R: k: d  set intersections roads with9 C' i0 g- h' R6 q: k/ t$ F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
9 M+ M9 m5 ~. H! {) l$ `4 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& W/ ~( ^0 C, p7 i( M/ p6 r: O
) z& S9 _. S; Q7 I& w. k$ V2 K  ask roads [ set pcolor white ]
# ?6 p  p' u& M* I- J$ f! U- C    setup-intersections
4 Y3 a1 w% A$ e; b8 S* qend
9 Z) A9 V5 Z( ^/ y3 ?( u9 J& I其中定义道路的句子,如下所示,是什么意思啊?% H+ Q4 F( K3 r) j3 f
set roads patches with
( v3 k% b* b' R$ Z; ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ k& {+ X: A9 b- u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ Y1 i6 N& G' {2 N# M9 `3 |% 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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