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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。
* \- S4 K) g+ \- B2 c7 vnetlogo自带的social science--traffic grid这一例子当中,
  ^- u' f) b  g5 I. c* @, A! b8 pglobals
+ g  p3 b& |! }% v, J[
$ @- D8 ^# _7 o  grid-x-inc               ;; the amount of patches in between two roads in the x direction. ?9 j! y$ v" W5 H# I  |
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! N. ]$ u# D" i7 m0 A4 }  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 e6 C  `3 Q% Q6 a+ E" W                           ;; it is to accelerate or decelerate
7 }; a8 Y. V/ @2 h; A8 @6 @- b  phase                    ;; keeps track of the phase# E0 }# [+ t4 ?( {* [
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
/ F6 D6 N' {3 V) V" g+ V  current-light            ;; the currently selected light
% V$ ^5 w' p& p3 U+ `7 T/ C( l' @! O! U" W
  ;; patch agentsets  h2 o# a, ^* T% T2 W
  intersections ;; agentset containing the patches that are intersections
: S# D* X9 k7 u# K8 Z  roads         ;; agentset containing the patches that are roads
. g. \( `: F: L1 D4 m]1 _( n  s  L1 V2 v
% u( w! E, ~+ i4 X4 g! s: z7 }
turtles-own1 D; q1 A: y, o- z0 k4 u! H
[
* C; C& v* k1 u6 Q  q  ]  speed     ;; the speed of the turtle
) N" t; v6 `. Q) D+ `9 W  up-car?   ;; true if the turtle moves downwards and false if it moves to the right% V% u% L/ l& x- Y- ^4 i3 D
  wait-time ;; the amount of time since the last time a turtle has moved; w. L' A. E% J' L* [
]" K. i2 B# ^& H+ ~# |8 x2 E
) \2 O: f) ]( e1 H* T) M
patches-own1 x) }. |% |+ Y) z' `
[
! i8 q. M9 t1 W  K" a  intersection?   ;; true if the patch is at the intersection of two roads9 Q0 ~' d" d& J0 F9 [9 j5 F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& B8 g* y: m! h2 `1 `% S                  ;; false for a non-intersection patches.& _% M, i4 w+ K1 M( a% S
  my-row          ;; the row of the intersection counting from the upper left corner of the
7 |  a8 w* n. f# R4 I1 e$ q                  ;; world.  -1 for non-intersection patches.
3 l; P' I! ~" d& f& ?: @  U  my-column       ;; the column of the intersection counting from the upper left corner of the0 Q% [0 I, P% C& x8 J. N8 `
                  ;; world.  -1 for non-intersection patches.
7 Y  y8 {; \, {8 K$ J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. C) {  K- I& h, s1 I  auto?           ;; whether or not this intersection will switch automatically.
' w8 n/ Z+ i9 P5 T+ u                  ;; false for non-intersection patches.1 b/ i/ {/ y4 d( o* ?. \9 }5 G/ z
]
+ Y/ h, i0 K5 C2 c7 v  `8 y; B1 B- C! X% S& k
3 l/ l4 n- x' r) E# u
;;;;;;;;;;;;;;;;;;;;;;+ C2 P3 L1 z3 j1 E: r: _; \
;; Setup Procedures ;;8 P; M( K; Q) Z
;;;;;;;;;;;;;;;;;;;;;;' e9 W3 J( j5 A+ @

& o4 j; Y9 y6 q- Z2 I;; Initialize the display by giving the global and patch variables initial values.
( g5 M" m) _- C/ w( ~4 h;; Create num-cars of turtles if there are enough road patches for one turtle to
9 p' r8 }( T! ]6 p  C;; be created per road patch. Set up the plots.
2 H0 T" m# b4 cto setup
1 ^% N, k2 o! }8 w  c  P  ca0 d" q9 Y3 h7 O8 v& q
  setup-globals
8 g1 m" u' Q; e) v: ^$ A
0 i- A+ s: |; ]/ C. l$ z3 D$ R& j  ;; First we ask the patches to draw themselves and set up a few variables' C2 Y( u8 Y" u. q7 s. w
  setup-patches+ H3 D8 M, R+ X  D* [4 X/ C
  make-current one-of intersections
) D1 P  [1 F7 H: h% c' m2 _8 n  label-current& e' [* L5 X, j( _3 e* Z
4 C& y# W$ S$ I/ L& x" O/ z& O4 t- `
  set-default-shape turtles "car"2 Z. J4 |3 G; f# O" u5 }7 ^6 L
: W# F( `% g! [9 |
  if (num-cars > count roads)( l$ b! m( K+ F, R# [( G% `
  [" j- @; `- t- c) I' g: W
    user-message (word "There are too many cars for the amount of "6 f  M. b. G5 ]0 J2 F8 ]
                       "road.  Either increase the amount of roads ", x! o& X0 `# P) D# P* Z
                       "by increasing the GRID-SIZE-X or "
' \- G0 w, G+ D1 y                       "GRID-SIZE-Y sliders, or decrease the "
& L" b+ c& [6 _                       "number of cars by lowering the NUMBER slider.\n"0 o2 B2 c, Y5 u' I; e
                       "The setup has stopped.")
5 s8 R1 a- c/ A6 a% d3 U! Q    stop" l$ h2 _3 j1 B# b7 w7 j/ `: E4 U) i
  ]  L5 I8 z( {2 Y1 L
+ A8 q7 N7 n( Y; D. p/ K5 U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 @- r5 Q2 J9 f5 m# ]: Y  crt num-cars1 @" }$ b  O" {3 w; D
  [
: y, V9 s' P3 U/ V    setup-cars
& r4 I2 D3 i1 E! l    set-car-color
! J3 B, b% p1 F* W% X0 J    record-data
% F7 a9 C- A. [2 r% J  ]  X* m$ V7 X" i1 s; L
' P, X1 V( b. s' {) ~) r
  ;; give the turtles an initial speed
- {% s  v% d+ `4 G  ask turtles [ set-car-speed ]% x2 f) q) H, r, D

8 R; a0 J  I% _& Q+ b3 L  reset-ticks, A. b6 \- e  f% u3 I: \
end
" L9 O6 `* r% z1 _0 H1 e2 W! A! c8 T* U
;; Initialize the global variables to appropriate values
: g; @( t6 a3 D8 S! ]to setup-globals% @4 b- ~: y) R& }( y& K
  set current-light nobody ;; just for now, since there are no lights yet
+ E7 C( n0 w% H$ u2 N  set phase 0
4 a+ W5 @0 ^, k- J  set num-cars-stopped 01 v0 J: k' b$ N
  set grid-x-inc world-width / grid-size-x$ i5 _. G" d- v) q% A( r* ~% v
  set grid-y-inc world-height / grid-size-y
  {) R  ~8 k9 h. ]( d3 ~
1 y4 O9 Q, u! @* g5 s+ w  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; a2 o4 G3 Y8 Q4 _3 H2 n
  set acceleration 0.099, k! r3 V; `; W) J" Z- A
end+ ?& j4 O% R# D( ~- X! U& a3 T& `) f
; n! C4 H9 e, h1 Z& O
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
& f% `: q* m9 o$ G0 D/ F;; and initialize the traffic lights to one setting4 t1 ?2 W& x1 ^( Q" _
to setup-patches
  H" M9 n, M( f8 m5 ?) I% c7 T  ;; initialize the patch-owned variables and color the patches to a base-color' M8 n* N2 A# i3 X
  ask patches) x9 u7 B, ^0 i% o) h. W8 u
  [
0 V/ X  {( v# |  Q    set intersection? false
% s4 f& r7 H# ~5 q& m3 r    set auto? false% ^; j5 `& t3 B5 J2 b( X& @
    set green-light-up? true
! _3 b. Z$ [" s, ^5 R3 y    set my-row -1" `% D) W) L$ G* w7 r* [
    set my-column -1/ `  a% f) Z% n0 z% O, [
    set my-phase -1
6 U$ ]' b& g, T' w4 h! j    set pcolor brown + 3
/ `( G5 f& c7 z4 S8 }, Z$ t  ]
! l& m6 B6 c' U) z4 v5 X+ X/ u% N. e: M( K7 e8 C
  ;; initialize the global variables that hold patch agentsets7 G+ g: v& k  ^+ b# I
  set roads patches with+ ]$ ?$ G4 h6 S' i1 h, C0 H% b: A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* g6 v. _5 ]2 N7 K- {2 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 X# d# k8 p3 F% q; J  set intersections roads with  I) m; h# d- n; c  j$ T" H+ |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 c" b. l# I% P8 `. ?5 Z8 A! U' @1 n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! ?; `% ]" o9 {- @" H9 l; t, K8 x! w
7 O% E  N& d; K- e5 r  ask roads [ set pcolor white ]
2 a' B  b9 t; j# Y: j1 ]' U    setup-intersections# O7 I9 ~3 I. A# j; U2 _
end4 b* t) b5 Q, b5 m' d% d+ z* E
其中定义道路的句子,如下所示,是什么意思啊?
' `2 A9 L5 ]6 j) ]  ? set roads patches with! |8 z: @. t! d% E# L/ N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ p% m. {6 D1 e1 F    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ J' h1 V, z3 P7 I# {) i1 `7 H' F
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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