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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。
# Q2 g# O1 Q( }& \netlogo自带的social science--traffic grid这一例子当中,
- S( A6 D! E, I9 Y6 Oglobals, k& t  f$ X4 \& y9 I
[0 s0 r+ A- L7 i, D+ w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 V- S- ?* p  v4 k: O  \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 A7 x* Y! X2 {& _6 m  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( Z3 M: [, T4 f$ ~
                           ;; it is to accelerate or decelerate
# _% I4 A  R! t2 l  phase                    ;; keeps track of the phase
0 a5 b* {1 |* u& U% E' n  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' p9 O% U' h- W( Q; B
  current-light            ;; the currently selected light- G, q2 A7 L: w" y5 V1 [
! @* J* n. l3 Y$ M8 H
  ;; patch agentsets
2 ~3 \4 E' L; R3 D/ O  intersections ;; agentset containing the patches that are intersections
( V" O$ t  w! h+ b; d' \  roads         ;; agentset containing the patches that are roads
: d* D8 I  T  l( D1 V$ l/ O* z]4 G0 w$ M4 ?2 `7 ]6 k
" T1 J* C1 E' W* y  b' t) x$ X+ |
turtles-own1 T6 Y% a2 t1 M6 [4 f
[2 L; k$ Y! e5 Z$ K8 e- D/ r
  speed     ;; the speed of the turtle
( [& j* z& a% m5 x* v  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. E4 d3 F  z, `/ R2 Q  wait-time ;; the amount of time since the last time a turtle has moved0 U; @  J% \* a( A# z" x8 r
]  f6 c( G5 B# ]
; H! B/ I3 V1 f$ k  _
patches-own% S5 K, i& J* l1 }
[: K2 S  A0 [) |
  intersection?   ;; true if the patch is at the intersection of two roads
# N" G( N, X$ ^+ |7 f* `  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ t! I9 y  \& B6 ~                  ;; false for a non-intersection patches.
- M) B8 b5 n/ y' W  my-row          ;; the row of the intersection counting from the upper left corner of the8 J0 ~( ?. V& j5 }
                  ;; world.  -1 for non-intersection patches., n+ v8 T1 x: H
  my-column       ;; the column of the intersection counting from the upper left corner of the* {+ t$ u( x9 }5 G3 O2 I0 e* B
                  ;; world.  -1 for non-intersection patches.( z  u/ z/ j- m+ T2 O' M! O
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 l7 g  t+ x1 ~. S
  auto?           ;; whether or not this intersection will switch automatically.1 _. X  s( v4 @/ v, e
                  ;; false for non-intersection patches.- `' F. }. m! b
]
- X' b/ M. C+ e* [0 l* @! s- P% J& e6 i/ p  k
5 a3 s6 e1 V% Y  W: {" C: _
;;;;;;;;;;;;;;;;;;;;;;8 ^/ B& m0 t! p0 S+ p: A
;; Setup Procedures ;;
1 k. U2 t! {" x3 W8 I6 @% y0 V! Y" p;;;;;;;;;;;;;;;;;;;;;;
1 \6 e5 ]$ n' k+ g  d6 H+ I7 W, K: g) U
;; Initialize the display by giving the global and patch variables initial values.$ V: P& E2 [& w
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 F: W# C3 T- S3 w0 L;; be created per road patch. Set up the plots.
  ^5 E' ^! c6 f. D0 K4 ?to setup
, `4 k$ o( F$ O  ca
6 C/ E) i9 h: s3 c  setup-globals* g! q" c. \/ f  m4 V& d$ H3 ~6 G

' i7 x9 R- K6 O: G  ;; First we ask the patches to draw themselves and set up a few variables
, `9 {" s. J7 a  setup-patches
" l" @" r3 i) O0 r) K5 o! b  z/ v  make-current one-of intersections3 Y* j7 H0 Y$ c! ^; n- l7 p$ r
  label-current% E  d6 k! R# j! g5 X8 H4 V5 j

6 O' q& E0 q2 I8 ?& x# {$ _  set-default-shape turtles "car"
9 }4 c9 ?* q- u, U! O" P/ T9 @8 K5 m( J; V! B7 E* Z
  if (num-cars > count roads)
- E5 A6 J: L2 ^  [
* x9 S( E1 `$ y. u& t, s    user-message (word "There are too many cars for the amount of "  i3 Y# ^0 L1 s- c$ j
                       "road.  Either increase the amount of roads "* M8 \  ^9 s* `; p8 L2 V
                       "by increasing the GRID-SIZE-X or "
3 r9 W) T; E2 e2 g                       "GRID-SIZE-Y sliders, or decrease the "
4 G1 [8 s7 @, m1 n7 v                       "number of cars by lowering the NUMBER slider.\n"
* f- _8 G# q& l5 i' l) C9 Q                       "The setup has stopped.")! N$ Z: O' s% h
    stop' p2 @0 Q0 Q+ K* A) L9 W5 W) G" Y
  ]
' N1 J7 R" e; }8 u9 ?* f& l# i* B) r8 B5 N1 \; V+ G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& m$ ^3 v. p. k
  crt num-cars
; P3 u8 b, t% M! O5 I- p  [
9 Q+ I3 z9 L5 j5 J' w& c$ M    setup-cars
+ d  n% p: E8 t( N    set-car-color
. ~. s  H! a& s5 n# c. y& D    record-data
; q. f! \* v9 G( Z  ]+ K& B4 V+ M2 d% l* N2 u7 |$ c

9 ^8 ~' y# C& ~8 l5 b  t# l6 I  ;; give the turtles an initial speed  `, V& j7 p7 y% o/ i" K1 H9 O- u
  ask turtles [ set-car-speed ]
% A  ^. Z) F9 u! _/ \5 [, `
& z. U2 ^: {9 D$ N  a# y, N0 W9 Z  \' C  reset-ticks
: i- E- O! _( qend
& C# U9 D. {* ]& s0 [
" S% H6 g8 b& n. M% m, w;; Initialize the global variables to appropriate values9 `3 R" p0 y1 s; k
to setup-globals
6 S& \$ n6 Y5 ?  set current-light nobody ;; just for now, since there are no lights yet
6 l1 _( p  P3 m$ x6 r  set phase 0) Z9 n, \, m, u% y% e: j. L8 u
  set num-cars-stopped 05 j( X5 k2 {) T& c9 d) ?
  set grid-x-inc world-width / grid-size-x
9 K( p# @* b! \% K, E) ?  set grid-y-inc world-height / grid-size-y
1 k3 s6 l7 ?" h7 H. n# D7 N0 b! M* E; J
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  T: r7 T- h( H1 ~- \4 M8 V  set acceleration 0.099- o0 m' `0 w( B' @
end
0 e9 q- M) a9 j: Q. _
# Y% N  E$ M  F; g;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  ]3 S7 ]- c( E/ P. C
;; and initialize the traffic lights to one setting
# Y& \8 \* P/ ]8 ?to setup-patches# `7 W7 }2 R! K
  ;; initialize the patch-owned variables and color the patches to a base-color
: L: C# M! W/ M  _0 g- p9 K$ y; X  ask patches. k" k. n( s1 o% F4 B1 z
  [
! @+ E, H' a- i/ ]    set intersection? false# L: G* ?+ b3 t
    set auto? false0 K2 \6 i: S  u5 g0 F$ G1 d8 c
    set green-light-up? true
9 {5 P2 |' v5 m+ s    set my-row -1
/ C- q' W. u) r$ y7 q    set my-column -1
& I; ]  N6 ]2 ~& R    set my-phase -1: d0 S+ L# B4 t
    set pcolor brown + 34 v8 n! z3 J4 F5 x9 c3 h$ o
  ]4 k' O, g; g% e  i+ o1 x; _
+ q2 \8 t5 ?3 y0 |
  ;; initialize the global variables that hold patch agentsets  I* n$ K) X# a
  set roads patches with
) h3 S. v+ P* s! F& C& i3 a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 D; X, {6 Q) u& M7 a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 |3 k3 ^4 \, c( u- p/ T0 j, J
  set intersections roads with
% q/ k" b' h* J" t( N5 j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 R% Y# ?4 I' {4 m" w7 Z' |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ j( v! e  p. d9 {8 n+ A) W9 ~& G9 R% o1 I  ]7 w: o
  ask roads [ set pcolor white ]; {7 s4 W% U8 K4 m9 i
    setup-intersections
  `% w3 z( j$ d9 @& G' Iend2 r, w$ D( ]- @8 |
其中定义道路的句子,如下所示,是什么意思啊?) \8 O) E8 W, Z1 W$ C- V' I
set roads patches with
# N! v+ \9 M5 H! f( d' k9 ?" {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 C. ?' n# p5 ]( @5 S/ W( S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], R0 y; X. L% i, j( y5 }( f% F5 p
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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