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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。
# v$ H5 N7 ~7 c& M/ ]% a6 O! Rnetlogo自带的social science--traffic grid这一例子当中,& L8 \! J8 r. M  M+ I# |
globals
, ^4 d% n) ^* ^  e. k, Q1 Q8 B[3 q/ c' g+ g. A, i* d, ^3 N, a# i
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 C" K( M9 V3 ^  }0 T
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! m! d; i/ Z! ]! [* a+ ]/ X/ v  acceleration             ;; the constant that controls how much a car speeds up or slows down by if5 _0 h1 K. t6 j+ G% F
                           ;; it is to accelerate or decelerate
3 `# q/ y& G8 k( s  phase                    ;; keeps track of the phase+ R9 P: C3 ?/ D$ W8 u( c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ ]  E1 z( v* l& H" a$ \& Q' [  current-light            ;; the currently selected light( Z; Q! t  }/ U7 k( Z2 q

. H( U  N- E: q7 e4 K/ }  ;; patch agentsets5 A: O- g& {5 L) g* M/ \0 Y7 N5 H
  intersections ;; agentset containing the patches that are intersections  C4 c* g! R( b) m* A8 B
  roads         ;; agentset containing the patches that are roads
- h; k  u! U0 X  G]
/ t. I2 f6 d# |7 O9 I; O4 ]- T1 M9 T: ]+ v
turtles-own+ i' ^: R- n2 x4 s6 d
[
; V) ^7 K! a' [, q8 X7 X. w  S  speed     ;; the speed of the turtle
; t8 y$ t5 `# H( H" [8 L  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 E# V( O2 \. d" o3 E$ |% C  wait-time ;; the amount of time since the last time a turtle has moved
' q( m8 s0 {2 A7 A0 K% {( M]( K# o( _( O0 K) W/ x; X7 y
2 n  s% y5 D4 N" o% B  D
patches-own8 W% r; v. o- [
[9 a6 Z6 v/ G& N3 j: k4 J9 d) O" ~1 b
  intersection?   ;; true if the patch is at the intersection of two roads
/ S% X1 _7 e. Y# `) H* ]! u5 P  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
, s# @$ A4 n( V; x+ ?                  ;; false for a non-intersection patches.
5 H9 f3 F" F3 E3 h6 Q: W& m6 L  my-row          ;; the row of the intersection counting from the upper left corner of the' h9 I. P' `$ U1 G- S$ Q! s
                  ;; world.  -1 for non-intersection patches.5 O( L9 d( R! A. O$ s; R4 K
  my-column       ;; the column of the intersection counting from the upper left corner of the' j" b" r* t; _" l0 B
                  ;; world.  -1 for non-intersection patches.9 \" ~  [) W" ?) y; w% n
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* k2 w8 u% C( \( X  auto?           ;; whether or not this intersection will switch automatically.
6 o  @: Q* \) _' @                  ;; false for non-intersection patches.
( H. |. @+ ?& B]% n- S0 r* i4 H) c
6 \* v$ e& d; a4 k% [& e0 e5 x0 C

0 b6 a5 G6 _( @$ q$ V;;;;;;;;;;;;;;;;;;;;;;
$ P. @' Y( Y! z6 g  q1 X, }2 a6 H;; Setup Procedures ;;; k& s8 Z. L* a; ?" u! [
;;;;;;;;;;;;;;;;;;;;;;
% J* X& w  T! s3 @- \4 t6 S- r2 K
;; Initialize the display by giving the global and patch variables initial values.$ K/ h% x& ~  R2 y
;; Create num-cars of turtles if there are enough road patches for one turtle to3 X+ b3 y6 e' \2 ?4 `
;; be created per road patch. Set up the plots.
8 H# X, _' T$ }to setup5 J4 }2 V2 L- l) s  q+ q
  ca
  D% n' m, D4 P9 q, `3 y, S2 i7 X' _  setup-globals
/ S) B, M. ^# ?, ^5 R; I7 ?# E  _0 K  [/ k% _0 P7 L5 w
  ;; First we ask the patches to draw themselves and set up a few variables
2 N+ k1 l8 J% G6 b  l7 k6 J# }; S. R  setup-patches2 B$ ]. s4 ]0 t
  make-current one-of intersections$ R3 R4 k' y* _3 l8 @& C: B) h
  label-current
: t" B+ ?8 H4 T
2 b# g& w  l. K! L# j  set-default-shape turtles "car"
& {; J, ^* m; N+ u& S) J
" ^0 F3 u+ D1 P3 o  i2 I! R  if (num-cars > count roads)
1 G6 O1 X% f0 e; j$ b, l# t  [
# D) t' `0 e% j" k) J- e    user-message (word "There are too many cars for the amount of "! h* L# z- T# W/ ]0 T3 N
                       "road.  Either increase the amount of roads "1 f9 N7 @0 Y  g. H& U. l/ f
                       "by increasing the GRID-SIZE-X or "
4 r/ v3 G- X$ b+ ]( D" [                       "GRID-SIZE-Y sliders, or decrease the "
$ P5 ]- v$ M- a, {; C7 D                       "number of cars by lowering the NUMBER slider.\n"
0 u% B9 h. }7 v, }* d% ^2 x) O2 `                       "The setup has stopped.")2 L; a$ ]  G5 q; i" a9 g2 B- j
    stop
7 S. l% _; X9 L" q! c2 B+ K! i. k  ]1 r& @) D' h4 u) X0 ^+ ~

- m0 F; S, b* g+ _2 ^  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% t7 B6 d5 z0 H' `0 O* d2 v3 S, S
  crt num-cars/ U" P7 P1 X: c& d. O) e8 }
  [6 Z" ^3 a8 b+ ]
    setup-cars
8 H6 Q. }, z& C, v7 Y- e$ K    set-car-color+ v. R% g; F! z: Q4 f
    record-data# A& w- m2 g- H. Q. T6 |
  ]
, y8 K& L% z, r: h! g: V* N
2 i' K# Z# m( |* L  ;; give the turtles an initial speed
8 |& g3 F* w; \5 r8 m$ ~* b* }; ~  ask turtles [ set-car-speed ]% q) `2 T; I9 P* n* H# }2 P3 g

. F% i* V9 J' ]% }  reset-ticks
( ?7 C; Y/ N$ k! Pend
0 G1 W5 `6 `1 R/ _3 Y) o
3 Y4 H) p0 f7 G2 j  _6 @;; Initialize the global variables to appropriate values: Y' ^* x5 N) d/ y9 w* @
to setup-globals0 R6 y3 g; }: g! W; k' h
  set current-light nobody ;; just for now, since there are no lights yet4 L7 B  R: q, Z1 R/ H! Q) f
  set phase 0
; D/ Q' ^3 W- P5 }# w  set num-cars-stopped 02 [8 y. E8 h% ~, [) T' y
  set grid-x-inc world-width / grid-size-x
* ^+ _5 m& V' j, B3 K  s  set grid-y-inc world-height / grid-size-y( z  R4 R  e/ Y  D& k

- e5 e& O5 O7 u  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- U6 z4 W) i# ?( ]# w8 ?
  set acceleration 0.099. c. k/ c0 d6 s' j" e& k
end
0 w( _4 U+ f/ w( G- F5 `
" M6 _8 ~2 r& P;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( x: M! F1 u1 P; n
;; and initialize the traffic lights to one setting
) V/ R3 b  v/ [2 Dto setup-patches: U" A$ I$ ?9 V0 s0 i
  ;; initialize the patch-owned variables and color the patches to a base-color
" l9 ^5 k6 m" ?( d9 @2 p& H  ask patches& d0 ~# b0 ]* P3 y) ?( e
  [
6 _9 p- x+ B7 I  f9 F1 h& }    set intersection? false
( ?9 J$ [1 q$ u6 M7 I    set auto? false
; a8 N9 t: ~" A9 }& e    set green-light-up? true
. |, K6 t3 Z0 a$ z& {/ ?1 k* r    set my-row -18 y3 X4 I# t4 N  m2 r8 Q
    set my-column -1
' t# f* \7 c) r/ f' I( [    set my-phase -1
0 H) Z" u0 b2 }8 K0 s    set pcolor brown + 3
# b, y! p" |# ]' S" _  ]1 o2 z1 G% q! f

! `" ]5 b3 t5 k, {  ;; initialize the global variables that hold patch agentsets
: d1 e7 I6 J& }5 n3 _# e5 l7 m  set roads patches with
2 o- I1 Z4 M6 @% @6 k5 E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% |7 ^& V2 z+ d9 v# A. _. o6 O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 V% X: U, }7 u8 T
  set intersections roads with  F: k' _6 Q" J2 H- i" Q$ h8 ?
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 r- n5 P! ^0 b; C4 W3 ~  F! _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. \7 z, Z, N! j) |7 ], I

. t0 ]$ R% Y8 \6 T4 k$ W( s  ask roads [ set pcolor white ]. Z; p8 e8 J# ]1 ~
    setup-intersections, |6 n5 }- [  J# A, P% ]
end
. Z( a* `! ]# V) O3 x! H' b其中定义道路的句子,如下所示,是什么意思啊?( Q2 h" _1 d1 y4 y+ x6 o
set roads patches with
. Y$ C- Z8 d/ y- Y3 a8 r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 j) h. B) u' _$ n7 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# B- {+ w$ Q8 C% L# W
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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