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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。1 I2 j+ y; S7 H; G, G. g" c
netlogo自带的social science--traffic grid这一例子当中,
2 `% U: c" h( @1 ^+ t' [4 hglobals
+ G; \( j# S0 ?- l* e/ q$ h[2 [. R; W6 ~8 m1 c! k
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  r. t! m+ B# n( y  grid-y-inc               ;; the amount of patches in between two roads in the y direction- H' T# ~/ ^* I
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
3 q1 h2 o7 D3 W% l- ^; [4 I                           ;; it is to accelerate or decelerate
- S6 V8 C# u" I2 r  phase                    ;; keeps track of the phase
) r# y" f7 E9 D* ]* a. ~1 r7 a# W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- e# f; T7 }/ ^4 U, [
  current-light            ;; the currently selected light! c3 L0 U. w( n" _0 o

- n$ @3 o. p1 q( z( N  ;; patch agentsets
" Y: A% W& l& _+ ~3 m  intersections ;; agentset containing the patches that are intersections
) O6 E" R- k) Q4 S9 N  roads         ;; agentset containing the patches that are roads9 }8 x3 `% z0 L+ L6 G  N$ J
]
& Y) P( X! b7 T
4 @) ^* Y" ~2 |0 f. F) I% }% Rturtles-own
! H* e& [" U8 E, y4 H  w8 b+ u, x* }[
$ j3 F/ `) Q4 L" u  speed     ;; the speed of the turtle
  j" t' ^' e! P( `  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 M, i: S9 F# O; F+ o1 V& X1 W7 b& T
  wait-time ;; the amount of time since the last time a turtle has moved
! L) D) V# j" |4 w* W/ Q7 B) s]
; n& ]8 I. }% x6 t. ]' B7 {) e# u
patches-own8 ?7 O3 g5 ^; ?) X' W
[
7 Q0 \  U# n& e7 z% ^4 |& \/ p0 U, N7 e  intersection?   ;; true if the patch is at the intersection of two roads
' @1 D3 g+ p4 x) y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! O" v. z% C! M% }
                  ;; false for a non-intersection patches." [: K2 t6 t9 \& A9 W$ u
  my-row          ;; the row of the intersection counting from the upper left corner of the$ i) L  w! r8 w% H  W( I5 P# D# j
                  ;; world.  -1 for non-intersection patches.
8 ]! R0 ^9 b# v6 ~; D* l  my-column       ;; the column of the intersection counting from the upper left corner of the' h. }3 [& q5 H4 r$ t3 Q+ o% p
                  ;; world.  -1 for non-intersection patches.$ u+ Z. Z* I$ H+ @' x* L
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 g) N9 Z) s  `/ N
  auto?           ;; whether or not this intersection will switch automatically.) [* Z! u. _+ N1 }! c9 `
                  ;; false for non-intersection patches.
. o8 T) J$ |) c]
0 N" O2 l* q; Y) ?0 Q  w# B
' d! R1 v3 I8 T# A1 f8 R/ L, f% q: u  r( M
;;;;;;;;;;;;;;;;;;;;;;
: w, a1 M, @* v+ Y% m;; Setup Procedures ;;2 {  a+ h% ^. S: m
;;;;;;;;;;;;;;;;;;;;;;
" w5 b! R! a3 a9 z
- V. R+ x; V9 ^0 O( C/ j' [;; Initialize the display by giving the global and patch variables initial values.% P1 H! _- H3 x# V
;; Create num-cars of turtles if there are enough road patches for one turtle to2 J. j: }- C5 o6 U3 G) f
;; be created per road patch. Set up the plots.
5 `% ^2 q  f6 A" c* I4 }to setup7 G: `# \% A( h5 P9 r
  ca& j/ t5 T: p" U5 e' V
  setup-globals
/ ^2 {9 K9 b" I% D8 v# k* E5 D: k. |5 V2 ]$ C- w6 y
  ;; First we ask the patches to draw themselves and set up a few variables
1 l) g6 P$ A0 a, @0 N5 U9 j2 Z4 P  setup-patches
: w2 d, w* O5 K  make-current one-of intersections; M# L- K8 ~: K5 |0 h
  label-current
3 p9 f. M6 y4 I8 J' g
- j" t. }4 q$ e  set-default-shape turtles "car"
6 i+ C- X, L- o6 I1 C; n( B8 N- p: i" o6 Y: N! V5 W. e; g
  if (num-cars > count roads)
1 ?: ~4 p. j. |6 ]. v! S% J  [6 ]7 b  u9 {; e
    user-message (word "There are too many cars for the amount of "
# \  V/ X0 r/ W) E( m$ X$ w  E                       "road.  Either increase the amount of roads "
5 ?0 k5 A2 j: C+ A7 i( Q# X& @% D; n                       "by increasing the GRID-SIZE-X or "
- M5 E/ Q/ r5 _$ m& D# S                       "GRID-SIZE-Y sliders, or decrease the "
) M8 o1 C# m$ f                       "number of cars by lowering the NUMBER slider.\n"
0 h1 u  o6 U/ q" B" B  m                       "The setup has stopped.")
& M( y# L' q- S    stop5 v; z( b# [8 I. J* z
  ]
* w& P: \7 \# r4 @  p; a7 }1 t0 S; U" x! Y9 X: N  g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ ?/ l4 d) ?! l6 Q. J7 f* E7 X0 o
  crt num-cars
. }- p4 u# d' ^  t# s/ u8 V  [
/ \: D1 H" J6 s% E5 ~    setup-cars
  \  V8 K( j6 L8 v    set-car-color3 l5 G1 z6 s+ Z6 Q% w
    record-data
, N7 b9 D8 P2 E" |  ]/ n5 T) T. k* q0 s% {; ^% U

' t$ a* D+ ]( R: M/ {9 l  ;; give the turtles an initial speed! w4 }. w4 ?. |2 A% y( ^/ h; {
  ask turtles [ set-car-speed ]8 V9 n" ?1 A; @6 h6 \
' [  {- i: h, J
  reset-ticks
# w8 q% n. E9 Y1 q0 Lend
& C6 p  ^; \8 q# n+ C/ u* x" @
;; Initialize the global variables to appropriate values
$ }0 E# Z) e( @/ `! gto setup-globals& [6 [0 |5 ^# e0 _1 R
  set current-light nobody ;; just for now, since there are no lights yet5 N$ C: X8 U1 x9 J" Z- i. S
  set phase 0. f. o. ], b* F# a& Y
  set num-cars-stopped 0
5 a4 D( [; a. F# c) b  set grid-x-inc world-width / grid-size-x# d6 V/ f) x: q# N2 Z
  set grid-y-inc world-height / grid-size-y
  K" d% f9 p# `* M& q
# Y7 A; k) H2 ?' M5 }+ ?$ ~+ x& V  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 I. O' w5 ^7 I' N1 f- K" h; G+ l5 i
  set acceleration 0.099
4 |* z) v9 P# Z- i1 tend
8 d! _, G: c$ Y% m" a* a1 X7 @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 z8 p4 _9 j9 l- W;; and initialize the traffic lights to one setting
- w" d, L. P( t- `1 A* tto setup-patches; u( x, q: g" a3 x# z) ]; ~6 U
  ;; initialize the patch-owned variables and color the patches to a base-color
  H( y% l) W% |+ N# k5 ]: F  ask patches; v* {; r  L( O
  [, t/ F& N5 @' n$ S% [
    set intersection? false
/ y4 K2 P$ [( Z; Z$ O( s4 R6 d    set auto? false! P) q8 g: |% G; G( D  N, j/ \
    set green-light-up? true
4 s2 q1 T8 O/ S' ~2 i    set my-row -1
/ s" W9 q2 d% A1 n    set my-column -1
  Y. h$ d: w- p# p, V    set my-phase -1. U) c) e6 }3 u& W7 e2 i& ^+ b
    set pcolor brown + 34 {4 `) T: B1 ^, c
  ]
& p' K' Z4 i8 I6 x& @5 n# t+ N9 ~' A! @& i2 Q
  ;; initialize the global variables that hold patch agentsets
) I, n2 V6 h( E  M  P  set roads patches with5 U, _) K! @& Q  M5 ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 b; s  j& u6 d7 e6 a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% Z0 A. r4 y! z
  set intersections roads with
- }  k$ j! f0 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 _9 d5 C2 ]; c! r  v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' o- O1 }3 c( f$ J; G7 G

& m( d; u6 R7 x* V+ o5 X0 Q. p$ d  ask roads [ set pcolor white ]( x, {0 z) L6 [- `5 ?, c
    setup-intersections
  n4 I1 R2 G0 Z, Eend4 `# o/ ^2 R2 l& m2 P
其中定义道路的句子,如下所示,是什么意思啊?
/ B# [& p! m* M7 h set roads patches with6 ~- \. X* n" H2 B7 R, A  N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, n) N* F. Y$ n3 h/ X$ W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% M, _0 j9 o6 i# g7 m1 d; 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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