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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。
4 O$ T6 F; T5 Hnetlogo自带的social science--traffic grid这一例子当中,$ ]& ~, B$ k! M  i1 x# s
globals
$ K# L6 k8 V0 W: A+ n2 z/ p[1 F8 W, i$ o% }: K8 U( V
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ @0 F/ v/ b% C- [4 \4 A
  grid-y-inc               ;; the amount of patches in between two roads in the y direction( [0 F  P) @6 g. N$ U( ]% G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 v: i# [2 v' a; Z2 _# ]1 e                           ;; it is to accelerate or decelerate
& `, f3 G7 f- H  phase                    ;; keeps track of the phase
! z3 D: `( `* A. H: s8 E+ Q8 w  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 b  t9 S4 W& @$ I7 s  current-light            ;; the currently selected light
% r% O: I- g5 \- h1 O
1 `& q0 J/ G, x) Q0 }/ ]  ;; patch agentsets
+ F+ F3 L6 P8 D3 d- X$ d" D$ B  intersections ;; agentset containing the patches that are intersections
5 l+ Y9 n# C) Q( R, J4 U  roads         ;; agentset containing the patches that are roads" X5 k% ^; e' }+ z8 n" q! n" l
]( X! Z$ I& a/ I) {" r1 x
* d& u; B& Z( H5 C0 T: Q
turtles-own1 {4 o8 Y+ R, L  A% d1 l& O! ]
[
; Z# n( ]3 w: V3 o+ @% W1 ^3 L  speed     ;; the speed of the turtle& v! d1 ~! I" u
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ d2 |, R% ~, V) j' X  wait-time ;; the amount of time since the last time a turtle has moved1 Q- `7 _0 D/ y$ c
]
0 o" b! c' z% P9 B; J1 e3 \; _8 N! \0 y
patches-own
2 c) h, f( }* m[
. z6 f0 U0 w$ L9 y2 h% \4 A  intersection?   ;; true if the patch is at the intersection of two roads& e, |8 e4 ]% m/ w' a& Z" z- A
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 Y. m! V: n% H) q$ L8 @6 s                  ;; false for a non-intersection patches.& w* V* e0 \5 ~" Z
  my-row          ;; the row of the intersection counting from the upper left corner of the: U8 S& @3 [3 M: e: W. g! s
                  ;; world.  -1 for non-intersection patches.$ L7 c) X/ Q1 r& c, _' y+ d! [$ S! H. [
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 m7 c9 d- X: T+ ^                  ;; world.  -1 for non-intersection patches.
& `" E( [( C, U+ Y" s9 |8 A3 B  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
# O* q' k# Z! p# r. x% H  auto?           ;; whether or not this intersection will switch automatically.
% |" G! s& ^, B. l0 _1 X                  ;; false for non-intersection patches.7 @/ t% r* q, X9 ^4 g8 g4 V6 V9 {' \/ F
]
' g4 _9 `) S: l8 u- W, [. E1 y  D' }( b5 c& c
8 v# C) L/ t& ^' T- o
;;;;;;;;;;;;;;;;;;;;;;7 V1 ]1 L$ ^2 W7 ~4 w
;; Setup Procedures ;;
+ d3 y+ u. w7 b' A8 i( F+ S$ @; r;;;;;;;;;;;;;;;;;;;;;;/ X, t% N$ X% d" M% s

* l4 ?: l, T6 N7 C! [! N;; Initialize the display by giving the global and patch variables initial values.# _4 U- _) B6 U; |' m# I3 s( O$ ^
;; Create num-cars of turtles if there are enough road patches for one turtle to! E) P, H( z& `. ^4 o) z
;; be created per road patch. Set up the plots.
; ^6 t/ T5 l* H/ yto setup; k+ Y: ]8 L; x* @1 i! _
  ca' L1 Y% X* X3 U+ S
  setup-globals( w7 j2 J+ p8 T. G8 m/ d6 Q
5 G  J# Z" R) L6 f: L0 A2 N
  ;; First we ask the patches to draw themselves and set up a few variables
4 V; |) O) A$ m; v9 l: D* A  setup-patches
- G; ^2 N( T  K0 a5 M  make-current one-of intersections
- \2 ~7 u. c+ b2 ]( H* ~5 k  label-current% m' p% j4 p  H( L# B- S& i
3 U, B) _! [, p
  set-default-shape turtles "car"' {5 l. `1 ~, G8 P) ~' _. u
+ y5 [% Q  m. Z: M7 m& C: A0 |
  if (num-cars > count roads)
6 [+ E$ B, i( a; U  [# Z. `. _8 @* V" A& U% e. m( l
    user-message (word "There are too many cars for the amount of "
+ G& [% {. f/ R  I! |$ ^6 z2 \                       "road.  Either increase the amount of roads "
% N0 W  ]/ m1 w; W2 U                       "by increasing the GRID-SIZE-X or "! S% g% N; n3 `5 N$ i% o) ?
                       "GRID-SIZE-Y sliders, or decrease the "6 k" E  F/ h+ u; o6 X1 d
                       "number of cars by lowering the NUMBER slider.\n"5 L( C/ a7 ~  j+ |4 D0 S
                       "The setup has stopped."), Z3 S1 @2 C& T0 T4 r! y; A/ U
    stop
- U# D! c7 E4 S3 s  x  ]
$ Y! z. |" Y6 ^# u+ @
; }- d  M" H5 k# {  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( {+ P' m( @! w, E* y' I% x; n
  crt num-cars
! Z+ B2 e# g+ ?3 ^( B* D; D( _  [
; P% l* ?% b* v3 N1 C2 R    setup-cars
) h, c7 }0 p: T3 C) W    set-car-color2 \& M; e; U2 N  h& Z" e) V8 D
    record-data
3 [4 J( r, D6 l5 O$ g  ]
. F6 ], a( v4 I' U4 L5 A
/ a8 ^0 T( ~( f. S  ;; give the turtles an initial speed
" J! r: j" S" c  ask turtles [ set-car-speed ]  {7 y7 f" e5 [( H

% b! o9 `$ s# c. G  reset-ticks- ^8 E" @/ S$ A$ {$ s
end
. S: y% l2 H) v, U9 W% g9 H* Y' V
" c+ }" B0 e$ p7 S0 ^;; Initialize the global variables to appropriate values
3 Y! L* V# M+ A. H: P+ j0 m8 Oto setup-globals9 G; R' s) j' ?/ f. k7 T
  set current-light nobody ;; just for now, since there are no lights yet
+ w! V9 T' w! Y4 S0 N2 U  set phase 09 H+ V1 E7 B  Q, x. \) f( x9 g& L
  set num-cars-stopped 0
  B- Z' ~7 Y* b/ C) s: q  set grid-x-inc world-width / grid-size-x+ u- [) \* }3 U
  set grid-y-inc world-height / grid-size-y; p$ ~: ^& z" |* l: m

$ a8 u; Y' [6 ~% S5 y$ M8 m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  V! l+ v" }! h2 Y  set acceleration 0.099
/ p! \9 m7 q( p' e( G9 R$ ?8 ]) vend
  @! a1 k/ m/ y# p
+ c; n3 |- y; N;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  b+ v9 I! z' Q0 [5 ], h# h;; and initialize the traffic lights to one setting
- f) t  G& n$ @; z6 ?% a; bto setup-patches
9 ^( A' M2 U: d; a' e  e  ;; initialize the patch-owned variables and color the patches to a base-color& V9 {* K3 ]8 N7 C
  ask patches$ J$ k6 s1 _& N5 z7 \  X
  [
4 Y1 N' b% W* o: E+ K; `    set intersection? false
+ C! }8 K3 h/ Q7 G    set auto? false
9 e/ I% K& l+ g    set green-light-up? true" E2 Q- s+ w: }5 ^& ?8 D; C: v8 ]
    set my-row -1
2 e- k; _5 R; I' I$ e    set my-column -1
) X4 A0 g* y, |0 t1 e! d    set my-phase -1  u" N1 U7 P) }/ m5 [& x
    set pcolor brown + 3
& w" l/ z' s& p% E  ]
' i6 K$ t, W! a, H$ y! Z+ C+ i2 t: L) T1 X& P
  ;; initialize the global variables that hold patch agentsets, ]- k, O- n/ @6 f
  set roads patches with
& d9 C  S  a) _6 h) O! R8 ~! `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( B  G: r2 B4 b  M, a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ v& X. s  x& P9 e' @3 u
  set intersections roads with0 |3 w8 o, }: R! y8 @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and' e8 e, L/ I' O# s2 \7 U  o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! U1 C! W0 x( M  T+ p1 D
3 V* J* j2 V) ^4 }
  ask roads [ set pcolor white ]
: @; l9 U" c4 d8 C, N0 U9 q    setup-intersections
" p2 m. b! Q5 c& kend
0 s' _2 i) K) `/ L# b其中定义道路的句子,如下所示,是什么意思啊?
! ]- o" x; m9 J, k+ Y  ? set roads patches with
6 B# |% {( y# f) T3 e8 n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& V6 {9 b7 }6 K5 g3 C6 y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- Z0 `3 |4 u" W8 z
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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