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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。
0 x$ h) ~' P/ Onetlogo自带的social science--traffic grid这一例子当中,! @9 ~$ I7 e+ v. ^
globals8 ]1 r3 Q$ A6 y, N5 h% d
[$ _% Q0 \; M$ T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 }' R5 P1 m  S) v, i4 z( z) \8 v* ~8 }  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 A* N7 W1 K& w" n  g: ^  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 D. `3 j9 L4 y9 ?                           ;; it is to accelerate or decelerate
/ t1 w$ T. h. f: q; G" n  phase                    ;; keeps track of the phase
3 ?- W: K( ?3 Z9 H/ u7 B, ]  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' _9 g' @6 x( f/ X0 N1 @/ }) Y) q
  current-light            ;; the currently selected light, M2 b. @1 L: ^! ^+ f! O% E* f( {' M

" C. s1 _% k  n' }3 V( u: A  ;; patch agentsets
2 f- N' q& J9 x" _  intersections ;; agentset containing the patches that are intersections
( p/ v, R& M# C" r% c: P1 q  roads         ;; agentset containing the patches that are roads
4 t- @4 U/ P7 d, ^, m( J]7 q4 a+ o' B6 ~. Z+ a$ \  C& x
& T! R( D; B  Z- V$ V6 y  u
turtles-own
. Z4 t( {* v2 c1 Z[
- F7 S5 l3 c1 I5 A; v  speed     ;; the speed of the turtle* h( I  [- d( w4 Q  k8 C% M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- |/ Q; @3 M: s  wait-time ;; the amount of time since the last time a turtle has moved
# O  F/ g8 l/ [, a; p3 S3 U]) C* r/ K- O- K1 z

7 m7 i8 D3 _/ Y$ s0 x6 H  y5 Cpatches-own
3 q2 K. a" w) _[6 t% m* H1 m7 h9 B
  intersection?   ;; true if the patch is at the intersection of two roads
$ Z$ Q% p% ?0 ?+ C) I( \3 K  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) y6 j# g* }, N: v) D3 x) ~7 I, y                  ;; false for a non-intersection patches.( t% x+ O  w# V! I* [
  my-row          ;; the row of the intersection counting from the upper left corner of the& }' @( }: v/ j: ^' Z/ V4 k. T
                  ;; world.  -1 for non-intersection patches.4 c# N( W! K3 {. ?8 E: c
  my-column       ;; the column of the intersection counting from the upper left corner of the; w0 C8 |7 r% ~6 {3 U, A+ }
                  ;; world.  -1 for non-intersection patches.! V3 W+ K  a: d& l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& r% Z% ?4 J+ P, n* g7 \  auto?           ;; whether or not this intersection will switch automatically.
/ G! Q* A$ n4 v3 O$ r: X  N2 D- n                  ;; false for non-intersection patches.' I. m3 Z# E( ?% Q5 c) Y, M1 S
]
8 z6 p& X7 n0 V% k: T" X' g/ F4 p
/ m/ \; i% E' N& [, M; ~2 N6 A) v& [+ X9 E
+ `4 a/ X5 L. @;;;;;;;;;;;;;;;;;;;;;;
$ ~, Q* Q( A  `7 P- |/ ];; Setup Procedures ;;# v  B. A9 Z" a4 c; k, [
;;;;;;;;;;;;;;;;;;;;;;  j1 d) K4 U: L8 L  n( \

: E" j5 r: D  s+ q; t) T' J;; Initialize the display by giving the global and patch variables initial values.% [* ^% I* B9 r: H; g7 I' {
;; Create num-cars of turtles if there are enough road patches for one turtle to/ s7 j- q. r% H# k
;; be created per road patch. Set up the plots.) R- `6 I! R: }( g" P! u% S
to setup
) D% C; j* I+ r  ca( L5 m) F) K1 E% ^3 b4 U: _; A
  setup-globals9 h, e& I; U7 t' ^, ]5 b
6 m8 S) Z$ X8 w& d3 M. o3 Y6 t
  ;; First we ask the patches to draw themselves and set up a few variables
' K& f' O% C" L) L% S7 c& T3 K  setup-patches
# `% k9 g8 b2 d$ z  make-current one-of intersections6 @; s4 u$ w; L" o3 z- r6 W( I: I! o
  label-current
3 @: h* O! ]" _/ @1 P* Y  x1 ?' ^. `3 Y" G( c; d' m% w
  set-default-shape turtles "car"7 q, h9 n5 m' z; ~1 w- J4 t

: |% q4 D5 }% z' m. O; G  if (num-cars > count roads)
" X$ u, i  K) ~$ `# @+ K  [
/ v6 A" I$ R1 S5 A# Y. g. j: {    user-message (word "There are too many cars for the amount of "; K3 D: B) z' v8 U0 ]/ C, Z
                       "road.  Either increase the amount of roads "$ }9 Z" \4 d( A
                       "by increasing the GRID-SIZE-X or "3 N- r9 ]6 B8 ~9 T6 O
                       "GRID-SIZE-Y sliders, or decrease the "  z/ I) ^# y7 @8 ^
                       "number of cars by lowering the NUMBER slider.\n"' S2 E- D$ \- `# I0 D! B/ F3 J
                       "The setup has stopped.")
+ ?3 c. Y3 h) t! J4 Z6 k. q9 P    stop
/ s* X; l$ u# M8 j  ]) d) m% H6 ^5 E' [

) J5 ~1 p7 w+ [# c. N* @* b  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. g5 G! C6 ^( }
  crt num-cars, j6 O; p) x* J
  [
# |5 c$ H6 |0 c* p    setup-cars
4 ~1 X1 ~+ D' s9 ]    set-car-color( |  {5 l) c: U
    record-data. R3 ]% a/ B1 p# J7 W9 V
  ]$ S0 T% @# {% E: e! d) V+ F
2 `- Z2 i9 K9 ~
  ;; give the turtles an initial speed
/ H7 a0 }; @9 ?) g; l  ask turtles [ set-car-speed ]
+ O! N3 v. G$ h+ D( Z" K) U
' Z1 v  i/ T& g# z* k  reset-ticks
% Y4 R/ G/ ]) x- i6 nend5 V+ s- ^) e: W
: x6 U: E' X& W
;; Initialize the global variables to appropriate values
3 T) B  U6 j% |( Xto setup-globals
! Y! l2 Y' @( ^3 V$ S% S5 t  set current-light nobody ;; just for now, since there are no lights yet5 i! T% u9 D9 K# W4 p2 n" B: |0 |
  set phase 08 M2 y* I! f2 j5 X/ y9 j8 D
  set num-cars-stopped 03 d! w& }# m/ q
  set grid-x-inc world-width / grid-size-x
% I! v) {, F* U. I7 j  set grid-y-inc world-height / grid-size-y
; t/ |" y8 K. V
2 t! G' ~, l6 {, K* c" K* M9 D  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ b1 A+ J# G" q8 C/ @1 t# c. x+ D" N
  set acceleration 0.099
/ |* r9 ?7 P2 e7 O7 j2 @& }end
! d4 s1 p0 y" @8 w
2 x( v* n8 |! _6 m# i, v;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: T8 Y- f5 i, J' y;; and initialize the traffic lights to one setting, C0 [& Y! p; k9 N* e
to setup-patches
8 E) b4 n9 I: v6 Q2 g# g  ;; initialize the patch-owned variables and color the patches to a base-color
: r$ T( \/ X! I  ask patches
. p& z  j- E- {; J0 Z/ t' y  [
- I- J- f* j. }4 Y    set intersection? false6 W3 P7 O4 a  ~5 u2 }" K% o1 a8 h
    set auto? false
  k" v% U+ X; o3 V$ L) f  z    set green-light-up? true) p$ ]9 m1 c2 ]$ t! G( C: V1 m
    set my-row -1
% ~! N1 L) F' t0 R  F- e    set my-column -1/ ]1 f* }' }8 M: _5 g3 u8 ^
    set my-phase -1
  P1 l# Y2 z! ]) Y( J' |# {2 Q" w    set pcolor brown + 3
) W/ z# A8 _. `! m) O  ]
! x' p" x6 s/ K  l8 t( U: `. |# C$ T3 `+ F$ A
  ;; initialize the global variables that hold patch agentsets
  ~# j+ T3 C, r  R7 u  set roads patches with
- X4 K9 f5 h( K, P# U! ~" a# _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, K# X1 U! Z* C% V0 N3 p& w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! G  C, u8 R% `
  set intersections roads with
# s$ l" P8 i, s/ s! D/ Y7 @# g- F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 N" x8 i! x: u4 C( ~5 B9 Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* h% A1 G3 P5 g9 a

$ ?  B2 l0 [0 c9 Q4 V, |  ask roads [ set pcolor white ]& A7 }: q. ]. R
    setup-intersections7 e/ c, j" m; i0 k  j4 d1 s
end
* [3 I1 }4 i1 d# y, [" y% o2 V其中定义道路的句子,如下所示,是什么意思啊?+ z% U$ x  [8 g7 ^
set roads patches with5 ?' A$ Z  d& S. {7 `  e7 L/ j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# [' k3 u- @5 u) k- H, e8 q5 v) W$ `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" U6 s: J3 ^6 t
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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