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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。6 c- L7 n3 C9 u
netlogo自带的social science--traffic grid这一例子当中,
) @/ p& l$ y+ l) Gglobals9 {0 Q9 w! C* N0 p& o+ U9 \/ y0 L
[! u+ h, D' @/ O) H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 H- n+ R' J: }) F) [  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  B- m0 S4 Z* q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) E  g/ G/ l$ t4 W% |( p
                           ;; it is to accelerate or decelerate
6 i5 g$ S( K: Q6 g  phase                    ;; keeps track of the phase
6 {- g0 D3 _/ z0 k: F' W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure# k% h$ t) U% Z$ U, G
  current-light            ;; the currently selected light& x" j3 F( I$ X

. ]. j% c# l) h$ M  ;; patch agentsets" x; K. q& F! W3 E
  intersections ;; agentset containing the patches that are intersections
1 S& ~, E! \# X- t( h/ I0 _& n  roads         ;; agentset containing the patches that are roads
3 d. D7 [5 @6 F' q]. T7 b8 A' o4 r+ {& }9 ]4 s

: L; v( u/ |' Nturtles-own1 B9 x/ f' G  P# w+ {
[
8 B: n/ Q  a' U. ]4 h4 V  speed     ;; the speed of the turtle% G/ ^0 _2 i0 T. r$ j3 Y
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 Z. v/ k/ F) F" f  wait-time ;; the amount of time since the last time a turtle has moved
: @, Z, t* W! S3 w7 p]. I- A- V/ [- T0 X6 z2 K, G
2 h, R- y1 p$ Y; A
patches-own/ e, I) R! k) ?7 t( m
[/ T( @* O: t1 l: c( b8 _# p: O
  intersection?   ;; true if the patch is at the intersection of two roads3 _$ C& G. T5 Z) |* C/ H5 _9 T
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 t* C6 r. v7 T9 C3 k- W' R
                  ;; false for a non-intersection patches.
7 f' n, a0 t3 T: Z# N- w/ t  my-row          ;; the row of the intersection counting from the upper left corner of the' |9 ~2 ~! W& U3 [' w. \$ S7 g. R
                  ;; world.  -1 for non-intersection patches.# n4 F) i# W; |# `1 ?- P' f
  my-column       ;; the column of the intersection counting from the upper left corner of the
: j$ V- ?- \( W                  ;; world.  -1 for non-intersection patches.
; j# J, R* g9 V5 k: }/ r/ u2 o+ {  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: I- s( r& o, }& l" [: `" y% w0 M1 M  auto?           ;; whether or not this intersection will switch automatically.& M. W* E0 F% s( W( e
                  ;; false for non-intersection patches." L) c2 Q1 `0 r# F' H. s* f
]
2 g4 W& A3 h7 d0 }1 O& L9 v/ p+ j+ e# w" }) ?' q% w4 j" r

3 N1 A/ c4 ~+ S) A/ c- W;;;;;;;;;;;;;;;;;;;;;;
- Y9 }# C& Z. s5 S5 c: N;; Setup Procedures ;;% \& H3 i  ]! z9 v0 w. T) N, c
;;;;;;;;;;;;;;;;;;;;;;* f& \& j' _0 h( b2 [( f
3 T- C! `% j6 q/ W, Q
;; Initialize the display by giving the global and patch variables initial values.
$ X6 p8 z( S- i& U;; Create num-cars of turtles if there are enough road patches for one turtle to5 ]' }  b- T8 V1 q$ A: K" w
;; be created per road patch. Set up the plots.$ F! V4 V% Y% Z
to setup
$ b( E# J% B" R7 Z$ `! X( T  ca. y# L; {- G3 Q
  setup-globals
, v$ }1 a8 f& J/ w+ n- H  P2 f* I5 D. P3 l7 o
  ;; First we ask the patches to draw themselves and set up a few variables
' D/ s. s+ m) W4 _3 i2 y2 R  setup-patches4 q2 E8 }  }' u0 r; k
  make-current one-of intersections7 `4 W) Q; R3 Y8 g+ G
  label-current/ Z# V3 y  U2 W! W" h& u3 P

* t) [/ d6 E# M& O  set-default-shape turtles "car"8 k% j, ]0 n, j# H! S" \7 t( D& V
7 T, P0 a- d4 u5 L% I. P# S
  if (num-cars > count roads)1 n' s) R) }5 S5 `( D
  [
! z9 ?- s8 j2 J& Z: H    user-message (word "There are too many cars for the amount of "
! W  u( e3 c% G. D; w) R                       "road.  Either increase the amount of roads "
) @( B- K9 }2 g+ X9 F( e' ^3 N& u                       "by increasing the GRID-SIZE-X or "3 F  g1 v6 t: k$ i  z" e
                       "GRID-SIZE-Y sliders, or decrease the "6 C' @& M, K' j) }; Q* c
                       "number of cars by lowering the NUMBER slider.\n"/ l) C5 {) U6 W; z& {. f+ \. v6 f
                       "The setup has stopped.")
& ^# s. y9 T2 T. n  x/ F2 z    stop: `# G: S  d  s3 K, [# `
  ]* J" c! s( V( Q; p( V- u" Z

9 @" |( [& b; b  f! j  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
4 v+ O+ }! c3 p% S; Q1 |- m/ E* Z  crt num-cars
9 [( E- s9 y3 e' ~/ k' g% ~2 Z( k  [
. R  r- g6 G3 F8 ~' e    setup-cars
) M) ~6 D8 r) d: S! `6 t    set-car-color  ^  c: P( f2 w
    record-data+ p8 k& Q; q8 j, ]- H* }1 A
  ]
" E) z, a! @7 m, y# z1 R! z4 I3 K
( B$ P6 S5 Y3 D6 t! D! J( {5 c* R8 D  ;; give the turtles an initial speed( f: n( ?* k7 ^2 d$ x
  ask turtles [ set-car-speed ]
, ?9 H: j4 f/ m9 J* q! O
4 i6 |0 D' _6 {% F3 z  reset-ticks
& a0 q9 a2 p5 b# uend
' x6 j3 V, i. g0 \/ M/ S) j% H  h! I% e" s/ |: W9 q& s
;; Initialize the global variables to appropriate values
7 x# e. b* P& `) F8 nto setup-globals' K' f6 D# ~! `
  set current-light nobody ;; just for now, since there are no lights yet
0 s8 J' U. w4 w' _( _  set phase 0
) Z# A, n2 C1 J$ B+ H  set num-cars-stopped 0" L5 A/ {. I9 {* e% H
  set grid-x-inc world-width / grid-size-x
; P9 o5 E% V- B# G0 ^2 X5 r! ]  set grid-y-inc world-height / grid-size-y
; T" k' F4 ~/ k$ _3 W# n1 {2 M( }# @" S0 c/ s' r
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. y4 R- V9 T# @
  set acceleration 0.099
9 ~- q8 y* K- u! _/ M# u! `end6 w: d8 H3 d* J0 ]0 T

3 k0 _2 q2 _! Y" v. ?;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 m' n) _* {5 _;; and initialize the traffic lights to one setting& N# [- B& z5 C* Z7 J6 l8 L( @, w
to setup-patches
) O* K4 J. C# |1 H  ;; initialize the patch-owned variables and color the patches to a base-color# z: e+ H/ g! I8 K
  ask patches6 b+ `5 L$ W& V1 u! L' g
  [$ D4 ?, Y( {* i* u7 K/ U. A* t
    set intersection? false
+ o: ^( ~9 ^5 U  l    set auto? false+ P* ~& x1 d( V4 v3 o
    set green-light-up? true; c8 B' w! P6 m" I! c; ?
    set my-row -18 ^) ^( g! j$ Z$ T
    set my-column -1+ o% b  Y" e2 {+ U# V$ Q7 r) s
    set my-phase -1, y4 F  k, I8 c2 \* ~
    set pcolor brown + 34 x' k2 I5 N  D. U
  ]
8 l: g' h, f" ^7 d8 \# ]2 c8 E, |1 b7 j: i1 I) x$ N6 y+ m
  ;; initialize the global variables that hold patch agentsets
) |' T& K0 v8 I2 {  set roads patches with
; i2 S# _1 l( t8 x    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! ^: ]1 X6 Y# d( D2 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% t/ f$ }& g. v4 O- [$ l  set intersections roads with& S% \- \5 W, Q2 A3 Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ A: v& @9 o) G8 \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# Y3 ?2 C. f2 b. }5 @0 k
7 h! ^: S& F/ I
  ask roads [ set pcolor white ]
" Z4 W# ~0 U) r. ~0 A    setup-intersections% ]$ z, ?' |4 m
end/ q! ^9 q# U" v  D( u( J
其中定义道路的句子,如下所示,是什么意思啊?! @0 W& M7 p6 S3 [( w. H7 n9 O: f
set roads patches with, K& X$ ?5 L2 w# O. t+ N3 I$ p; V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' p7 r' S% Z0 }5 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* o# M) i# K* f5 G' W' B. d8 n; x' R$ M
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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