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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。0 D) `) D0 N& Y( o0 N! e
netlogo自带的social science--traffic grid这一例子当中,
/ q- [% t- R" _2 U/ Fglobals& F; H5 p. Z- g2 [# O# D' k) f2 w
[
; y: ]; E$ U. m! Z7 }1 P; [  grid-x-inc               ;; the amount of patches in between two roads in the x direction% M4 w& S+ ^0 X9 r8 }! O) R
  grid-y-inc               ;; the amount of patches in between two roads in the y direction% l2 H) P8 U- O9 R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; U' e* {+ j  R1 i; f                           ;; it is to accelerate or decelerate9 y: i5 c" q" n8 q8 Y
  phase                    ;; keeps track of the phase6 \3 x5 t0 O& [/ s
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 L5 |2 K1 V8 V/ U+ t  current-light            ;; the currently selected light; o7 e$ `/ E# q

5 M6 e8 }: T% _) T! i* {  ;; patch agentsets
2 t1 }0 k. i, z  intersections ;; agentset containing the patches that are intersections
; R0 `$ k: l, l. Z: D* `/ R1 e  roads         ;; agentset containing the patches that are roads7 {1 ?+ S0 C% n6 P  u$ c
]
' \9 [9 \5 t( |
6 M& w% g( h& t* ^6 S& I- ^! n, o9 sturtles-own
" G, {/ x' j8 c+ {! `2 f5 R[
% T7 D8 ?8 X1 f7 ~  speed     ;; the speed of the turtle
8 N. F! {1 v3 v3 P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 J: g1 F  w- h1 I
  wait-time ;; the amount of time since the last time a turtle has moved
" C6 \2 q4 }- i- M4 P; K7 u2 x]7 M4 I- j/ X" i7 `$ W
/ u6 x$ W( V5 D3 T' a  w
patches-own
( E5 N4 h3 b! y8 Z) |& j$ P7 j[8 L) g% h# f0 B# O( V! ^
  intersection?   ;; true if the patch is at the intersection of two roads
1 B2 i2 H; Q7 f  I8 ~) Q% X" A, W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
5 B/ v" E9 ]" _- x, h: c* o                  ;; false for a non-intersection patches.7 p- s8 {% Q8 i+ Q, A
  my-row          ;; the row of the intersection counting from the upper left corner of the" K1 w2 L- H3 r; ]
                  ;; world.  -1 for non-intersection patches.$ O, A, m8 d$ D$ M6 k
  my-column       ;; the column of the intersection counting from the upper left corner of the9 t& ]# |! _# F8 N" N
                  ;; world.  -1 for non-intersection patches.6 H  \; `4 Z6 O/ P' t
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# V3 _, o7 k  ^: v( F/ Q# W# c& W
  auto?           ;; whether or not this intersection will switch automatically.
$ f' `" k* K) M; ~7 D$ M5 Q: w                  ;; false for non-intersection patches.. @9 [/ ]- S: k1 o* e, H! G* w0 R' ]
]6 M* q" N' D& k  D5 w. }+ U- j

& t* \5 Z; l9 {+ c$ m0 J& Q4 R$ g/ x% H9 B1 y
;;;;;;;;;;;;;;;;;;;;;;
* M3 C% v# \- u4 {& r9 Y;; Setup Procedures ;;; o+ y  u2 i% {8 y
;;;;;;;;;;;;;;;;;;;;;;; m8 D  }6 G9 F) r* ]
# T+ X' k' [6 v* ^. u% b
;; Initialize the display by giving the global and patch variables initial values.
9 X  i$ U; \7 v;; Create num-cars of turtles if there are enough road patches for one turtle to
4 N; o, \' y7 T3 e% E0 _% y;; be created per road patch. Set up the plots.. D0 x0 R9 p1 b9 ]1 ~
to setup$ Y% E2 @% m1 A7 W/ X6 A5 a) I% ?
  ca
$ v$ E7 `2 v' H* \6 v  setup-globals; K% n, [# ?8 ]* T
" K. T2 W  g1 M- w/ d- ~& f- \
  ;; First we ask the patches to draw themselves and set up a few variables: j# f! F1 V  m- l9 E9 C) {6 f
  setup-patches
9 T; S% |( {$ H1 \- d' h  make-current one-of intersections
& E3 e; s  ?7 X% M0 h' C  label-current
) ?2 Z9 p) z8 F* |0 ?
0 G7 y. U! `% U  set-default-shape turtles "car"
6 ?. A# k+ y4 r1 {6 G' }' H2 l6 B3 f" |0 m) N
  if (num-cars > count roads)+ h( o2 R8 N; S7 o
  [
0 z$ g8 b) K; g( |6 h; {0 F    user-message (word "There are too many cars for the amount of "8 q! ~0 [1 W9 K
                       "road.  Either increase the amount of roads "" [  M' ?, b' }2 U, a/ q
                       "by increasing the GRID-SIZE-X or "
5 Y6 Q7 D. f, c; q                       "GRID-SIZE-Y sliders, or decrease the "
  m4 K) N5 K& A6 M( A$ O7 |                       "number of cars by lowering the NUMBER slider.\n"
: r& R( u+ i; T# ]                       "The setup has stopped.")  s7 D7 A: a, }8 U0 Q6 p7 F
    stop+ G; f0 \% z* B. W
  ]( n  i- k  V% }% B& L" J

7 }8 m  x) W, W  w  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; p4 D3 O! \5 \  i2 Z  crt num-cars* P* f) z+ o/ M+ G7 h7 i
  [
' b1 t! o( ^6 w% O    setup-cars
2 X* N" _! \* F+ s' m) C    set-car-color
4 b' M3 [1 A/ L' t    record-data: D  h7 x* |) j5 _( E
  ]
' ~2 h" D0 s0 f4 u4 y
6 s& O" ?: S& d; L  ;; give the turtles an initial speed
- r+ Z5 w/ U) q7 I  U  ask turtles [ set-car-speed ]
1 e. q8 I; U& I) I  D% k8 B9 S9 z& c
  reset-ticks5 E) `) H- n4 p/ X  c& x
end
6 E! j" t$ A, R# l) d; j" b# Z8 U% F
;; Initialize the global variables to appropriate values
, h: x, v# }2 g8 {" fto setup-globals
* M3 g8 j. r. t2 Z  o  set current-light nobody ;; just for now, since there are no lights yet
+ \3 ~& d0 A: m. M7 n- Z' ]  set phase 0
( i" h# S6 s* t$ z( w8 u- L  set num-cars-stopped 0
; [7 ^" [* v* m' R  J, N, M  set grid-x-inc world-width / grid-size-x
5 {" j' R7 f: K0 [0 [& P  set grid-y-inc world-height / grid-size-y
7 t' u/ |1 e! @# `# A
4 A6 K8 E; c. s  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 M, l$ Y$ g* m' l% x$ ^9 ]4 {" \/ S3 w
  set acceleration 0.099
! u5 a  B. R* A( mend' S5 K" @  r+ ]0 Y0 j5 O' u8 o- _1 S
7 B  s  L1 ^  D) _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 I5 C. S- M7 d5 u: T- C% T% B  ^;; and initialize the traffic lights to one setting
1 Z4 p% N1 z% e% |- p' [5 Y# \to setup-patches: u. @) b9 d1 Y: U
  ;; initialize the patch-owned variables and color the patches to a base-color
+ }" `! A* k! @/ H" k) k5 A' j9 Z  ask patches
; }2 W! v5 r$ K* q+ {) U  [9 t5 E/ y% f4 _, k
    set intersection? false+ {/ ^' ?% }, q# n- N& J
    set auto? false
2 D6 w( s4 C  {* h: s2 E    set green-light-up? true
! u2 q( V9 J4 f' |9 x6 z    set my-row -1/ G' H; Y. S3 ~
    set my-column -1
2 I" a" j( v& ~9 u/ b$ _6 S* g    set my-phase -1
, s+ h4 {  Y* f3 b    set pcolor brown + 3
* D4 O& O! |  D/ U  ]
5 t0 k- {0 I+ {" ~4 ?9 O7 ?; [# M+ r* J3 Y2 U
  ;; initialize the global variables that hold patch agentsets9 T0 i! p' k- S7 {; @; K( h
  set roads patches with
- q. Q2 v: I/ R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 y, M" ?+ L# m1 k( p9 l1 _& s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ I3 O* E1 A+ o, G- T! a
  set intersections roads with
7 c* ~7 W! J, t2 p/ ?* T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) p0 T$ V" S# w% S$ ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ E# W  G: Q9 H1 \) B0 O: p9 y3 J
  ask roads [ set pcolor white ]
6 t/ t6 z6 V5 L5 t$ V9 G4 r    setup-intersections  W) D3 m7 s3 B0 a# S7 v
end6 |0 x9 E; N! a4 X# {3 o' V1 Q  h- @
其中定义道路的句子,如下所示,是什么意思啊?
. [2 O  ]4 d) q& r/ u* p set roads patches with
7 D4 S% p3 f' w) K3 H5 e% c; j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 J: u% \! M( d2 T9 M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 c6 X9 X' D$ b5 H+ c& N9 s
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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