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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。5 s# c4 ]+ E: ~- L) w" z% c
netlogo自带的social science--traffic grid这一例子当中,# r, V! ~2 J* m% U9 ~
globals0 O  O' }& @2 _, U
[2 d* T: i9 x3 ^' @- O/ p
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 |6 x4 l5 M) f; w; ~* d  grid-y-inc               ;; the amount of patches in between two roads in the y direction# U1 x) K& x' D/ L! ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 j  o6 m, [: D1 o" W) U8 I6 \                           ;; it is to accelerate or decelerate
  n6 j. o& g7 c  phase                    ;; keeps track of the phase
$ d7 |% e- q8 L' {  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% g- r& T: w5 x) Y& n
  current-light            ;; the currently selected light7 |9 Q7 Y# A. G

/ e# U5 Z8 o" C; Y) ^, }0 m  ;; patch agentsets( j  Q3 p: \' z- V' _/ S& l" `# L
  intersections ;; agentset containing the patches that are intersections- x9 x+ N6 B0 ^
  roads         ;; agentset containing the patches that are roads# o/ J' _4 `+ E2 c( @. [+ k% }+ Z6 O
]8 z6 z( J2 i) e# l' b
! _8 z; Y4 M6 n: K$ ~/ S
turtles-own0 h" h" k$ \; b& q
[
" p: f/ O, b: [+ D9 g  speed     ;; the speed of the turtle
8 C5 _# z1 c" O* }" n6 r. N  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 M/ b5 O5 P5 w: Z. Z: S
  wait-time ;; the amount of time since the last time a turtle has moved5 q. F8 p+ M; m2 v, K9 i
]& B5 Y! v, l% ~
( z% p- {! x5 b4 y# @" W
patches-own4 N) k7 j" g* ?
[
: i! V, ^3 W, u- w$ b  intersection?   ;; true if the patch is at the intersection of two roads( ?2 O2 y1 U5 z$ J; w4 g; l0 R
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( X  ?1 h# g8 x0 ?
                  ;; false for a non-intersection patches.) k" \4 |  {# P2 {
  my-row          ;; the row of the intersection counting from the upper left corner of the+ r5 f) T9 y/ @# W1 r2 o
                  ;; world.  -1 for non-intersection patches.  Q9 @# G8 k& F
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 f+ X# s; Y/ d$ h                  ;; world.  -1 for non-intersection patches.
8 T2 k4 F6 S3 H1 u4 q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ b0 s* H8 w, g5 r9 ~" w
  auto?           ;; whether or not this intersection will switch automatically.
5 F0 z3 @" ]1 j9 ~! }, [                  ;; false for non-intersection patches.
, l4 |8 {0 Y5 c( b+ p. K* t]
/ p$ K# I* Y5 h6 e9 T0 B
' |. q3 l0 ?1 q( I6 ]0 J
* m% X8 H' C% R; y/ l& q6 w5 X;;;;;;;;;;;;;;;;;;;;;;
7 z  {7 v2 a/ q, a* [;; Setup Procedures ;;+ u8 ?. U! T9 M; g: `- o3 a+ F( L
;;;;;;;;;;;;;;;;;;;;;;. b2 o  y8 ]0 N4 G, L5 C5 U  g
( l) S9 p* g! P- R6 B
;; Initialize the display by giving the global and patch variables initial values.0 {1 F3 F4 [: {2 J" }+ u
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 L8 y- c6 `+ |5 I- D;; be created per road patch. Set up the plots.
  u" S# }. ^2 q& A# M; R/ c3 l0 Y9 m8 Fto setup
% m/ p+ H( X" {# K( i( q# H* b  ca
. f) `+ V' g# e  setup-globals
. H4 m. M7 C6 \" F6 T- o' I/ ^5 w8 ]3 z$ }1 b8 e( Y
  ;; First we ask the patches to draw themselves and set up a few variables, {  g4 W* a$ q: R) y+ n: q
  setup-patches3 L* z8 V2 |( I2 E& S
  make-current one-of intersections
6 s6 z6 {! C3 ~2 F0 [  label-current% x/ D( q; q6 J0 y6 |1 W& C# m

: Z" i$ j* H, y& z  b: w6 Z" S  set-default-shape turtles "car"( _+ h' E2 N3 p1 [: f6 d2 ?
. m6 Q' D  p0 G8 e: [7 Z3 t& O4 |% F
  if (num-cars > count roads)
% H2 r) }( g# J2 a4 e8 c  [
. p% c1 d( t4 w* q( Z: ]  c. c    user-message (word "There are too many cars for the amount of "& v& S3 Q; u! V+ |
                       "road.  Either increase the amount of roads "+ U" o+ a1 ]1 `0 T; J
                       "by increasing the GRID-SIZE-X or "( s3 I# Z# _2 z* ~
                       "GRID-SIZE-Y sliders, or decrease the "
, G) r# P2 y# G4 t) `5 K, \                       "number of cars by lowering the NUMBER slider.\n"
( Y0 y4 e" _( y# H- J                       "The setup has stopped."): R# {' n3 H' n) l
    stop, R: ^2 K/ O! F+ p% g, T
  ]4 S! r, m+ r5 r
9 M! C  b3 e4 W$ e6 x) S$ J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 @. x/ H0 t: e" T5 J4 L  crt num-cars2 f; f$ r' d* B
  [
3 ^% a; z% \( K    setup-cars4 P, b, w# m. d7 u1 G
    set-car-color, |& B$ |* M8 P  w0 T2 G; s
    record-data
" d  [2 v4 X' u, [& P  ]2 X# _5 b$ Z& v4 ?

( [1 i8 k8 m" e  ;; give the turtles an initial speed" A0 V: L& k0 @+ i! F& x
  ask turtles [ set-car-speed ]! Q' ?5 y( |# R# F' m! Z4 R2 j

( C# v! ]; A" k3 c2 q' R6 b0 m  reset-ticks
9 Z  c3 E5 h# D: Nend
4 G9 f  |( m4 s: a: r) P2 C7 y/ ~- u9 R4 C; L$ a* ?
;; Initialize the global variables to appropriate values
( i8 E, R  ^- I9 l6 S$ t  vto setup-globals
8 f: B* U( @" ^) p- j  set current-light nobody ;; just for now, since there are no lights yet
% z5 _! Q5 N) a: j2 {  set phase 0
! u8 W& L  }2 R% ]& a; l1 O( A1 j  set num-cars-stopped 0& p" ?# q5 e. g/ a6 f3 c4 K
  set grid-x-inc world-width / grid-size-x0 b- H8 ]/ D* B8 w2 a; d7 J! {
  set grid-y-inc world-height / grid-size-y( `2 ?' |4 X' ^# N5 n

0 w/ Q5 v8 |+ J% C- i7 e  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary/ U1 \+ f( d" F6 Z& Y
  set acceleration 0.099
- `0 W% q) k3 J" g' y0 T- Jend
4 _+ }6 s; E& n- p5 i* ~: c) Y) m2 R% }5 A/ g0 g+ Y0 U
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ [' h$ m  K" c; D' n) ]: @: c;; and initialize the traffic lights to one setting
/ R' S& @- w; k. U$ eto setup-patches: G3 G! A3 k' F+ w6 p5 F; T
  ;; initialize the patch-owned variables and color the patches to a base-color6 D6 s- F$ ~0 \3 X! R
  ask patches
$ d" ^" Z! P) M2 b  [( R' Z0 E3 N2 L$ U+ O" d5 ?
    set intersection? false- \( [7 ?3 s! |$ Y) d: G) y, `) K6 L8 M+ F
    set auto? false2 j) I: X' B& [9 m7 w4 ^6 @
    set green-light-up? true, ^: B- j9 L' N# H, A& d! O
    set my-row -1
& {: z  ?8 n# a- X    set my-column -1
" u- ?5 x4 k) `9 C    set my-phase -13 v- u: g  `0 h: o
    set pcolor brown + 3- l- R. K" d. Z" D; h- ^9 Y
  ]0 `/ o' k5 q' e. d5 Q$ h$ ~# R+ o
; w: O2 ^$ ]( c6 Y' k, `
  ;; initialize the global variables that hold patch agentsets
! s: E+ Z( ?% \; ~3 r  set roads patches with% I0 I, C: f- N. x3 s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  `. V1 e  x& X7 G    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 ]# `* |! u/ z% D/ m
  set intersections roads with9 O# R$ g0 ?. u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 b* k$ u" r& q4 A& A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& G1 G+ b- X$ d* J! A* U
% o5 Z) ~  s, b- Q' w5 i( o& P: @3 h  ask roads [ set pcolor white ]
; F; P; ?8 |% [9 E8 m+ y. Z    setup-intersections
0 p- {5 p! `- Lend- U  C: j# M' f
其中定义道路的句子,如下所示,是什么意思啊?
* T2 i2 f4 |7 t  n set roads patches with
' @* w* i7 J# S# C, r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 c" D9 E3 \$ j7 C" v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% W0 x3 t- N& h; B/ C. h$ c
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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