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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。
" n7 y& E: m& Gnetlogo自带的social science--traffic grid这一例子当中,' U$ }2 J) O1 C+ X
globals. Y6 V: P  |$ _) E; _6 Z# v( y
[  q1 ~1 v. i) z. {
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. O0 a( g% j0 [; V7 N2 O  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 N2 ]4 G2 q2 v: `
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 {- a5 @; h5 I$ X% }1 b( {$ w
                           ;; it is to accelerate or decelerate8 m- _7 s/ a* z
  phase                    ;; keeps track of the phase$ a! [: o( b) o0 V/ r+ I
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  m( F7 q, X8 m5 ]0 c: G, ^
  current-light            ;; the currently selected light
6 N! K8 e% B: }' N9 `, \
( @+ P9 O* @' l- B  ;; patch agentsets  K- q7 I4 |1 {
  intersections ;; agentset containing the patches that are intersections
2 ]7 F1 `' N* d6 B8 {  roads         ;; agentset containing the patches that are roads) ^5 q8 t1 \% m9 [) ]% I
]
1 H% {" f" I/ J' p& ^- f  U% d5 @! Y7 O) k; l
turtles-own
. l- Q; f5 s5 C% c% A9 U/ l- n[6 f+ o/ U7 M. D8 [
  speed     ;; the speed of the turtle" X! {( F  E. O' }4 X6 t5 v$ ^( L% R
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 o7 g/ h- b3 o( m1 b- \0 ]  wait-time ;; the amount of time since the last time a turtle has moved
0 k& Z2 N3 h! u]* r# n1 G& ?& D4 O0 T6 G

; H# m# Q4 d/ b1 N0 Cpatches-own' i/ C) S( d. [5 O& e
[+ E/ X( S$ o" S- }; H- p
  intersection?   ;; true if the patch is at the intersection of two roads
, m4 z3 `( p$ X  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 I2 i5 j+ T, ^5 s% R: f- t                  ;; false for a non-intersection patches.% D* D/ ]1 d4 Y/ C8 l
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 |. `, U+ Z' v+ B                  ;; world.  -1 for non-intersection patches., U8 }4 D1 A2 P
  my-column       ;; the column of the intersection counting from the upper left corner of the6 K8 k8 E% {! u# z- _3 Y$ Z
                  ;; world.  -1 for non-intersection patches.0 O" C- W2 }' s: }8 x0 \
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& q& a. s3 p  H6 L2 I2 W
  auto?           ;; whether or not this intersection will switch automatically.
" d3 D% d2 x3 p3 f! f: k" N4 s! y                  ;; false for non-intersection patches.
1 r0 v9 d1 @) V1 _4 Q( e; A8 o1 e. ~]
! j) R1 t" h  i% n" p& K3 i+ K6 n8 T( @0 p
. f- n7 B* Y" n2 i, p( V& q
;;;;;;;;;;;;;;;;;;;;;;( c  F# y1 o  a% e9 Q% Z+ q
;; Setup Procedures ;;: S0 g2 [% V  b, X
;;;;;;;;;;;;;;;;;;;;;;
/ f) I% C+ ?( a
' r# j; O  }8 A: U9 y' b;; Initialize the display by giving the global and patch variables initial values.
9 L# x$ F* B) q' h. Q& ~;; Create num-cars of turtles if there are enough road patches for one turtle to2 A! k& ]- P4 t# c7 k& n
;; be created per road patch. Set up the plots.( Q, l1 t8 w, Y$ ^8 R
to setup
. U' Q( P6 y  V( R, w  ca5 {* I. g4 O3 \+ x$ j
  setup-globals
$ G- j0 G6 K4 R1 y+ C3 g. M/ S! ?7 |+ v. z5 Q, ~# b8 @5 Y2 N8 ?
  ;; First we ask the patches to draw themselves and set up a few variables
' \1 J& [- M% ^: y  setup-patches
" w- O7 l9 R0 H  make-current one-of intersections
9 r2 ~/ e$ q9 w6 v  label-current
6 s# p3 ?$ a# s1 v7 w0 |1 b+ M1 V* J: u( U+ n. F0 n) n% h1 B) g! s
  set-default-shape turtles "car"
4 w4 J' b+ U3 ?/ ?( U
. l- P( w' }: x, ~7 _. P  if (num-cars > count roads)/ U5 P/ \* g( U0 l
  [
: S8 H5 M" O# `; A1 N! \6 r! H: K    user-message (word "There are too many cars for the amount of "% G, ~4 J' g/ d8 e# R
                       "road.  Either increase the amount of roads "
% x4 m9 n; b; `7 v4 F" {' C, `' M8 Q                       "by increasing the GRID-SIZE-X or "3 |. c! o/ d2 ]4 D
                       "GRID-SIZE-Y sliders, or decrease the "
2 ?4 y! V. m0 j6 ?                       "number of cars by lowering the NUMBER slider.\n"
. @3 \1 @/ e0 s                       "The setup has stopped.")
; K% ]% `! v* t8 W. ?+ s    stop" T. |" i( r) j2 n, i, \" U0 M% {
  ]
3 h( X. \3 Y5 S
" a4 X' O. u' F0 v3 c  S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; Z+ t1 p5 ^: c9 \8 n) t
  crt num-cars
1 ]5 q% V0 F' @  [
& j* s+ h1 g& d+ H; I2 r: h5 v" `    setup-cars" |9 n, X1 l1 L) B9 i
    set-car-color
! T2 I+ J/ E( n; l- R    record-data) K4 L7 D4 q6 L) b2 c- q) G
  ]
, P* X+ j" ]2 i# ^) l# F' k. e" m* `. u( F9 d
  ;; give the turtles an initial speed
/ |; X. a2 i( r8 z4 v; U$ B. ?  ask turtles [ set-car-speed ]& g. ~; O( i( ]4 l( s
+ c! J: j! U, I; t; K0 s
  reset-ticks
3 Y: Y) A- k5 L6 C& O4 gend
# d7 `6 h! Z3 I' J1 `' Q% i1 Z9 R9 T  A
;; Initialize the global variables to appropriate values4 r! l. O. v- D7 t/ f, o
to setup-globals
4 F0 M/ y3 g+ i9 A9 D  set current-light nobody ;; just for now, since there are no lights yet1 S  |/ L; P& J+ g" N+ W
  set phase 0( z: a3 b% X3 |  J9 }% P
  set num-cars-stopped 0
" F# g) w1 I2 y* \( Z/ A  set grid-x-inc world-width / grid-size-x& z4 G! f& X( ~& z6 |
  set grid-y-inc world-height / grid-size-y
$ G  O( H/ F5 O* q, a7 S! Z4 m2 d' h
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary; M9 O6 N$ d1 f  ]6 W  {9 x3 {5 n, a
  set acceleration 0.099
/ U7 Q( v+ O) Mend
- D/ A$ n8 E, w4 @+ `4 F0 F7 @3 Q6 [3 N: N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# Y5 Z! h6 C' F2 X;; and initialize the traffic lights to one setting
; I, J1 l( t' M) H; qto setup-patches
8 c4 ?$ Z- k( W  ;; initialize the patch-owned variables and color the patches to a base-color
4 B( R/ m4 V  v7 z  ask patches* o0 W' e% m9 x, }
  [
+ r8 f- b; O2 r# H& e3 c    set intersection? false
7 b' s7 ~' S2 O" _    set auto? false
( R# c% ~! L2 h# K# r; z2 n    set green-light-up? true7 T: U. d) G. ~: P
    set my-row -1' b+ j; n( P2 z3 p* T
    set my-column -1# n- o% Z7 \$ Z6 i- _
    set my-phase -1
/ @0 B- b7 z0 S+ Y    set pcolor brown + 3
% c' V! q$ e5 }3 T  ]& w% y! s7 R1 [, X" Q

: S$ R; N  V5 U7 s& V9 W- _: n  ;; initialize the global variables that hold patch agentsets
! h$ e& r6 w" l7 l  set roads patches with
) R. o' w; d0 G  I+ b" \' j: R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) g! p: l& [* x1 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 N: t; u  s, `
  set intersections roads with
0 Q9 \$ @  H' a1 d% ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 _: e' R1 W4 m, U& d* ]7 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, w! Y' N% |3 b7 d" p
1 e4 H( I% m+ v8 ]" M5 h1 h% R# I  ask roads [ set pcolor white ]
! E- v9 u: V$ O. j  E    setup-intersections
7 K! s: O, w+ ]: L, c9 o9 S, dend
/ y7 n2 _$ m2 l7 u其中定义道路的句子,如下所示,是什么意思啊?5 D8 @0 @+ Y8 q
set roads patches with5 k. P( u+ d0 h. [* h( `) S& m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  a9 q. P, o& k) W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( B9 _! L2 j9 v, q" g6 y) j7 u8 [: 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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