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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。
: e6 I# |7 `2 ?! A' n- Y7 Inetlogo自带的social science--traffic grid这一例子当中,0 `% G* @8 p6 p& S  b1 _
globals
  B8 e1 ]5 G( P9 P! Y& B[, U3 N( l: m* D7 @! H9 e6 B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) j# M, q# z" v2 C% D3 d0 I. {/ X  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 |' p" }  ^6 L  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ a. q# U' }# K9 a% S0 X8 N! |                           ;; it is to accelerate or decelerate* _! H9 M9 \* G8 {! x$ [
  phase                    ;; keeps track of the phase0 Y; s; `" V, V3 b% |# P! i* d/ D
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: F  H" c8 V/ ~  H
  current-light            ;; the currently selected light+ F2 H' c( N5 K# }+ [" }7 _; p, i
0 Y0 ]* J% J0 q- N
  ;; patch agentsets3 [6 y% Q$ e/ t! r7 b
  intersections ;; agentset containing the patches that are intersections
" j3 ?+ q% ~, k/ p* j  roads         ;; agentset containing the patches that are roads
3 Y  {. p! A8 q0 C( w]' \+ N( P, p5 b' F% U# h! A
/ E% y* e# M$ T
turtles-own
7 h  p4 i$ K7 n* w& q$ u! p[) o. e' J% h# M  z6 E1 c) {
  speed     ;; the speed of the turtle# i- H' \0 r: o2 r
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 `  w2 v+ {' s4 ]$ o) [  wait-time ;; the amount of time since the last time a turtle has moved
. e1 E  }  }. \8 `' i! f$ B]- _6 G: q7 H& A' v
3 O) w6 z  l5 H7 h" {( u* `
patches-own
+ [7 O. ^$ T+ t% F. C7 h4 w9 f[( o% [2 K( I  E9 C6 X  ^
  intersection?   ;; true if the patch is at the intersection of two roads8 h2 ?/ Q% O% K$ [3 r0 G9 s; e
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' l+ u/ j; o" l; x9 [! X) p# z
                  ;; false for a non-intersection patches.
) {# p' o$ r9 B7 @9 F  my-row          ;; the row of the intersection counting from the upper left corner of the
5 b" `3 k2 h3 E5 G, Z                  ;; world.  -1 for non-intersection patches.1 I7 B4 h8 q/ X; t& W( Q/ Z/ ^+ }
  my-column       ;; the column of the intersection counting from the upper left corner of the
3 L$ |. j  @+ P! g7 i* ~1 N                  ;; world.  -1 for non-intersection patches.$ h( S. ^+ o2 j0 b9 P- i
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; ]8 v. E- Y3 z4 ^2 w/ ~9 T  auto?           ;; whether or not this intersection will switch automatically.
) z0 _" d" z, L- h' C2 s/ n                  ;; false for non-intersection patches.
$ ^9 v; q6 y0 o* E. K]7 R" M7 M2 f4 P6 h# u0 N3 x2 j
2 f% ]  E+ y& _! |
( @+ M8 d/ q7 C/ Z( a4 U5 _" V( K# @+ G
;;;;;;;;;;;;;;;;;;;;;;
! S4 V) ], `/ n: S0 z) s, P1 N;; Setup Procedures ;;
. ?' @. Y6 j+ n, A7 q+ H;;;;;;;;;;;;;;;;;;;;;;9 f1 F1 U9 ~# [9 q

! M1 F/ E- n% y7 J' };; Initialize the display by giving the global and patch variables initial values.
- O% ^+ }; b  Y$ z- l/ w;; Create num-cars of turtles if there are enough road patches for one turtle to$ b, M5 p- }2 V) R1 y. k  X
;; be created per road patch. Set up the plots.
) j6 a1 x3 J( U7 A3 Q3 r2 o: xto setup
3 _  _1 j" k1 ^9 y4 I, t  ca
3 U0 E1 x$ `* M& x8 ]& {5 }  setup-globals
" W; K* S. ]: L% n( L$ H% `: h" k7 e, [% _9 f
  ;; First we ask the patches to draw themselves and set up a few variables: D( d( {6 j' x, m% G
  setup-patches2 K7 ^% _# p) C, q5 C$ ~" ?
  make-current one-of intersections% v! c( u! f: I8 r2 O- F
  label-current
% n1 Q4 T9 ^3 k+ N/ i. t" o
* Y) W1 Z- _2 q) b9 S0 @9 O8 O  set-default-shape turtles "car"& I% U; C0 {7 B; x) @
) ~) l; f7 Z9 w+ r6 B, O  ^
  if (num-cars > count roads)+ R$ C# y! F+ z% R5 w% {9 M* F
  [, n: j: @# T, f0 ^9 i$ E1 {
    user-message (word "There are too many cars for the amount of "! Q3 t4 |& e6 @/ f
                       "road.  Either increase the amount of roads "* R. Z, R2 O5 n& R8 j& f0 T# d' M& H8 q
                       "by increasing the GRID-SIZE-X or "
$ T: Z, N4 p0 M0 A! _* F                       "GRID-SIZE-Y sliders, or decrease the "
) j/ _7 ^; L" v: ~" Y7 B1 n% q                       "number of cars by lowering the NUMBER slider.\n"3 A5 r7 C) s1 ]! Q- t, f" \
                       "The setup has stopped.")9 T3 H/ |, @$ ?* S4 c; O+ h8 D
    stop* X! J. n4 E' }  A$ p  f
  ]2 z: q; h9 d2 [5 |/ z* g
6 D* C! m6 q4 f# _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
3 S+ @- s# [. s  crt num-cars
; o2 ?6 m5 b0 v, k2 l2 {4 Z  [
0 D7 w! q+ t6 ^+ K8 c! v$ p, R    setup-cars
; ?2 Z5 J+ w0 J: s& w$ }8 E  U6 F9 z    set-car-color
8 Q1 o* R( g  n# w/ y    record-data
! u" s" |1 f8 i( \& M+ K9 ]; F  ]
' m* B2 t) N/ f% `* a) ^2 ^# Q: M; N5 `/ D5 C
  ;; give the turtles an initial speed' o# y3 u' A/ M# {* p$ U
  ask turtles [ set-car-speed ]5 }0 C- Q4 n, T5 c5 U0 W# ~
+ a" a1 }* t9 I
  reset-ticks
9 d' @: @/ w1 L. T5 Zend
; O3 M" f( Y$ E# L5 g, \$ a5 @; h5 R( H! W: O7 X+ |
;; Initialize the global variables to appropriate values
, |4 ~+ w0 o% D" kto setup-globals
" s( P% ?9 U3 F2 o0 ]  Y8 J  set current-light nobody ;; just for now, since there are no lights yet8 Z# P# Z6 C+ Y3 R5 U
  set phase 01 C( V3 Q$ T7 G+ |$ }
  set num-cars-stopped 0: J% ]  j3 D2 U# U, D! ^' P6 ^
  set grid-x-inc world-width / grid-size-x
" E5 ^% R; r: N: M  set grid-y-inc world-height / grid-size-y! \" H% I) v, R  ~4 m, {
# r$ ~" j1 U) N0 m' o6 }& S
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% z. x4 x$ ~0 E' j( E. X
  set acceleration 0.099
6 n: B" S# V, J8 oend& n6 v9 S6 q; J6 q+ _( ?& s( Y

: h/ x+ S& a( A7 n;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ H. s8 _5 H1 `;; and initialize the traffic lights to one setting
: _+ H! ?' v) Wto setup-patches
" v7 I- l$ v4 o  Y  ;; initialize the patch-owned variables and color the patches to a base-color
# Q9 ^7 x% V+ ?4 x, B* }  ask patches5 {! W' x/ {# G2 ]0 }/ B% X4 h+ A
  [0 t4 a* P6 I; k; `$ U3 A! i
    set intersection? false
4 x& [- l5 j) f5 W    set auto? false0 ]$ n' `% X, _+ d  ?
    set green-light-up? true9 l2 ?: p' t5 Y3 j  w
    set my-row -1
5 B/ U  a4 [: C4 ^' a: @    set my-column -1( R& y6 Z% n( W/ C: j' M) P  A# O
    set my-phase -1
( P* n% m2 x" P5 U% n    set pcolor brown + 3
! Y# j3 @; M6 K  B  ]
- ]( ~8 X. ?4 U' s7 G, t  `$ V8 _2 x  P
" @, P* y/ H$ y" c3 S  ;; initialize the global variables that hold patch agentsets) _( r7 f  \5 I
  set roads patches with8 o+ C1 b7 p( c+ t1 b" W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 P$ Z0 {  ^1 O" M1 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 }* ^2 x1 H: `$ v  set intersections roads with  A- z2 F2 x5 c, X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% z3 m0 }0 [$ B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) x7 W0 ?. \( l, B. E! i
1 ~/ X8 y1 L/ ~1 k' n
  ask roads [ set pcolor white ]
, p) {1 J1 z/ e6 a' [    setup-intersections# m( w6 c! n# z" Z. g/ e
end* R  g: S' j7 Q9 [6 z( W
其中定义道路的句子,如下所示,是什么意思啊?
3 b2 B7 b) k7 ]5 g. c7 d set roads patches with
5 D0 d/ }5 ^8 j6 ]4 a! d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: e, _6 p* M% \3 C! f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 j0 |# b& |: f! A0 _1 D
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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