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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。
; S8 ?- ?  D4 k& x- \netlogo自带的social science--traffic grid这一例子当中,$ y4 \! ^3 r. ]
globals8 u  A# `3 v: U3 a8 E" V. `
[
- P3 x: m6 C7 P  grid-x-inc               ;; the amount of patches in between two roads in the x direction; `. ~' j; {/ T' h) t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ Q4 |  p% }6 H; ?1 u  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) q8 G! X! @- O( w: [/ r
                           ;; it is to accelerate or decelerate
. c$ H- \! o) }  [6 a- ^7 L/ E* d( ~  phase                    ;; keeps track of the phase2 s+ z6 A+ W/ z0 ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ _. p6 k2 F& p) y  current-light            ;; the currently selected light+ F# N; n) j2 s% L* l* r5 u

- q' n+ s8 l2 G- J+ @  ;; patch agentsets
2 \) D9 b+ i8 T/ K( w) b  intersections ;; agentset containing the patches that are intersections0 J4 F' E1 B. \! \
  roads         ;; agentset containing the patches that are roads, n0 n  I8 g( L% J5 r: D# O; P
]
5 k8 j' Z" [- }2 W
- G7 p3 |5 G- L, mturtles-own
: P& E. `4 F, ~6 N1 y[6 J2 Z% |9 h, Y% l
  speed     ;; the speed of the turtle1 l, j* u! `& q- g. N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" x) d0 m9 c3 a0 Q0 T; c7 _
  wait-time ;; the amount of time since the last time a turtle has moved. }0 }& Q' i, R* y7 o- _' D/ }
]+ D1 H6 e  q& `) E3 a$ }

$ [" l/ L" A+ wpatches-own  R1 w  L" n  t8 d4 N- B
[
3 @8 K+ ~8 Y0 q  intersection?   ;; true if the patch is at the intersection of two roads  J( g0 T8 _" K- @# T# {
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ Y/ N8 M( g' d' N) i( B* t, t
                  ;; false for a non-intersection patches.
# V  o5 w; x9 x" B' g1 _  my-row          ;; the row of the intersection counting from the upper left corner of the
$ `( K9 J0 X; m/ E; k                  ;; world.  -1 for non-intersection patches.
4 F- c/ f6 ^, v; M% G0 d0 t$ h3 {! _  my-column       ;; the column of the intersection counting from the upper left corner of the9 p1 l  c9 Y0 O! A* V2 G
                  ;; world.  -1 for non-intersection patches.  d7 ], e+ _; k. K2 V! N
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 Q8 r8 k, |4 l2 M. t  auto?           ;; whether or not this intersection will switch automatically." t! s+ ^" F$ P* o  K
                  ;; false for non-intersection patches.
  j/ n) @' w- [( W1 Z]4 q" _7 C2 C+ O# {
% v! d* \3 [) @1 G& V
1 g7 V% }& e  G9 r5 |- ^
;;;;;;;;;;;;;;;;;;;;;;
! X" o7 d/ P' Q" C;; Setup Procedures ;;
5 m4 {( \$ S6 q0 g;;;;;;;;;;;;;;;;;;;;;;6 U8 P0 L  N( Z+ |+ B! c

2 K  g; z$ E$ l$ H; t; u: j;; Initialize the display by giving the global and patch variables initial values.$ g" h$ R3 Y) L# j
;; Create num-cars of turtles if there are enough road patches for one turtle to$ i. q  W; {: M6 E! D
;; be created per road patch. Set up the plots.0 @# Z" S0 A' X0 d& W) R$ b
to setup  p6 e& U- ~! m2 l/ `
  ca5 S% @8 ]- I7 u& x- `
  setup-globals
$ S& G0 ?' s3 e% R$ R; U- @9 d. Q% S% J+ k6 ^- [
  ;; First we ask the patches to draw themselves and set up a few variables2 K) z5 `2 b1 D; V4 k+ M
  setup-patches
. M; z! g# ?( j$ ^  make-current one-of intersections' U" r7 k9 |; T- F" h0 `7 [
  label-current  [) t4 D  J: Z. ?) v" `
: E- L& ^- _) ~( [
  set-default-shape turtles "car"3 e, {& @) M3 B8 Z0 Z
- d0 \; @- P" t4 x
  if (num-cars > count roads)* c/ b4 D9 v( i$ }3 R6 J( F% f
  [
7 b* m: t6 i# S9 |    user-message (word "There are too many cars for the amount of "5 u4 @+ T/ ?% {+ m# U$ b, k
                       "road.  Either increase the amount of roads "
2 u0 i, z7 _9 |8 E                       "by increasing the GRID-SIZE-X or "
4 n% `' U% E5 e- J& |3 M                       "GRID-SIZE-Y sliders, or decrease the "
8 L9 v$ Z) H4 y  K                       "number of cars by lowering the NUMBER slider.\n", `' G: p8 E! h" _
                       "The setup has stopped.")7 X$ W! I$ a& K( e5 k: W
    stop
% m* |5 v- |; h- Y  ]6 U% a' J- o: A% ^: A
5 L# V2 {5 s, a1 M0 h/ {% C
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, T2 p3 R3 z1 i$ J" _$ [  crt num-cars: _0 Y* v: y2 f0 ~- T
  [
5 c8 z" u% e; @$ z$ J    setup-cars" E) V) P1 ~* M- h- x0 l- b
    set-car-color8 T7 W' z: y1 |; V5 b
    record-data
4 Z8 T' T' v# I! u% E- ?& c8 \- T  ]
! S9 b! z7 F  E2 K8 k1 n: c5 y* d3 t( I
) d4 f% h7 d, C  ;; give the turtles an initial speed% A& d, p9 N$ r4 g. |* @, y
  ask turtles [ set-car-speed ]% M$ @# T! B/ e9 |" e) e6 s- e% I
4 }0 e( L1 O; h# l
  reset-ticks! ^6 @2 f6 ?2 B' m! i
end) v9 E! O* O0 f
1 P  T" y6 {1 ^: X" v6 o
;; Initialize the global variables to appropriate values
8 ?7 r( B1 U" G2 R! A4 o( C; Lto setup-globals
! M! h( a# a& U* l- c  set current-light nobody ;; just for now, since there are no lights yet
- \* B& M$ p9 x( ?  set phase 0
' d8 N- S/ R) w( g* B  set num-cars-stopped 04 d: X! ^9 P3 b. I+ R; D0 _
  set grid-x-inc world-width / grid-size-x
' U" w! S# W( Y# |  set grid-y-inc world-height / grid-size-y; B8 Y: [# j8 w; x
5 L* g' ~% e: w  y, [1 `, }
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary4 ^/ ]( X) b, V$ M" E: I! t
  set acceleration 0.099
# V7 C! i. a5 e, ~end
! L+ [6 e6 ~3 _" ^
& M7 u6 A  r& W/ c  W6 H" o- A0 i;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 f# Q+ L+ Z2 b; Z3 u;; and initialize the traffic lights to one setting5 }* b: E+ U- F# }/ e9 X
to setup-patches
6 j1 d! i( j/ G0 [: P0 O/ F  ;; initialize the patch-owned variables and color the patches to a base-color
# `8 f1 ^5 A6 l" b+ e, X) v8 |  ask patches; `/ U+ J1 R, X$ W8 D4 t( S
  [
% A+ a% L+ l! a5 K1 C9 m. A    set intersection? false
) \$ H* M$ t+ c  p+ N    set auto? false
1 A: o& q: h$ I/ U4 {1 @    set green-light-up? true8 p: P; m$ |' @, x2 p) n& ~1 ?" Q
    set my-row -1
4 V# r# W4 D) y4 |- K# c    set my-column -1
7 ~$ G6 L$ U( e6 j" t3 }    set my-phase -1! V% T& f' J) }( F/ _8 _% ^6 K
    set pcolor brown + 3- @: f$ L7 b3 b. N2 H/ X  A
  ]$ U! T  x& [, k: y' y$ f) ]  l

/ f( V9 L  P2 b* F  ;; initialize the global variables that hold patch agentsets
6 X3 M; T$ @! p  set roads patches with
" j' E  g3 |" V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" l# N( @( V* Q( ^% q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* _8 G- A# @) {, a
  set intersections roads with
9 C$ c" f1 |" @% V: C/ Y' X! _6 @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! X. \0 F+ O7 F( X' g5 ~" M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, V9 x, B$ s2 X( a
; ?6 j5 y8 D+ n  ask roads [ set pcolor white ]
6 |* t8 d$ q8 D) ~    setup-intersections
2 j3 X, _2 t; I; r+ Uend, B2 U4 h- a! J" K3 z* H
其中定义道路的句子,如下所示,是什么意思啊?
: ]: n2 @7 B! Z  {% r5 d7 Z9 d# R set roads patches with; ?3 A+ A: a7 k" Z9 X; x) O
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ d3 K! ^1 V' }( J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; D- k4 D5 O4 V( R3 c9 \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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