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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。
1 i6 b5 f/ T/ m- Wnetlogo自带的social science--traffic grid这一例子当中," ?' P& S! W" a& M; |
globals
5 ?8 U4 \* H- `  H% u2 X[5 g: |+ }. s2 m! L& n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  w& V0 s* @0 {  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" K8 X9 o+ B. Q+ v1 `- `" w  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 F( }* X7 {' \. G9 S- s" ?( p8 k                           ;; it is to accelerate or decelerate
3 p! a3 R: z- g# {. R; H- H& F3 @  phase                    ;; keeps track of the phase
' Q& P! h, {2 a" [. Z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. }/ x" l3 K" E5 c- X
  current-light            ;; the currently selected light
5 }: m2 s; p0 c4 T! F4 E* M  N
( x. x& d& f2 S+ D' g  ;; patch agentsets
& r' E3 p& M, l5 F& V  intersections ;; agentset containing the patches that are intersections
* \2 z% Z% b. h& s. q0 G8 h  roads         ;; agentset containing the patches that are roads
4 h' P, b. d) b5 d& b]! F$ [5 w" @& V/ w* C& _3 k, @
) H0 P/ {' C  u; Y
turtles-own9 O) P* X8 R+ L9 |
[0 u' O- c9 u4 D6 s
  speed     ;; the speed of the turtle
; k, h- T+ G+ Y- |3 E; m, H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% i  L& C  I* B  wait-time ;; the amount of time since the last time a turtle has moved0 \7 n# W. a  A& v% w% J$ z+ Y! z
]; \: a0 u  w5 {! Y$ N- ~1 q5 X

* m: k+ A9 U1 @9 {8 s5 _+ y2 @patches-own
" u6 ^! C- H4 R; N[
4 j, \6 q) u2 P+ \  intersection?   ;; true if the patch is at the intersection of two roads
* k+ p( N+ m6 o# Z( Q  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 W# b' M( e3 T  M+ Z' V8 w  h4 A                  ;; false for a non-intersection patches.1 P4 S# q( N, p7 v; F, W9 O
  my-row          ;; the row of the intersection counting from the upper left corner of the
4 C! z! i7 i7 d) |. W  T                  ;; world.  -1 for non-intersection patches." [8 d! i) K+ S# e
  my-column       ;; the column of the intersection counting from the upper left corner of the
! s4 y! P: m9 T, E, Q6 V0 @                  ;; world.  -1 for non-intersection patches.! [* H. X4 ]! [9 B" r
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 J# j; |) @. H  auto?           ;; whether or not this intersection will switch automatically.: x9 b$ C6 B- v4 K$ e
                  ;; false for non-intersection patches.- G$ V/ T; |: P' x$ G$ t& c
]
% [. x6 Z6 b# J7 {) w
/ a. G. p# d& V( B! Z" b# _
4 v( O( \2 m. X" z) j5 X;;;;;;;;;;;;;;;;;;;;;;
/ [3 V) f( f6 P0 X* d& i;; Setup Procedures ;;
: x: b' @- T. N' W1 M;;;;;;;;;;;;;;;;;;;;;;
+ T7 b# C; Q& v+ V+ _1 v# s3 F/ Q
;; Initialize the display by giving the global and patch variables initial values.! o: q: E9 }% Y- m# X2 v) ]
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 A$ ~  d2 t( ~  T  u9 n; D; q;; be created per road patch. Set up the plots.7 o# e/ k2 w* H0 c# x/ |
to setup
2 p, ~- {: p9 {; j3 U6 I; f  ca
  a9 l4 F* {' D( u+ y0 E) Z  setup-globals% a9 t5 Q; R& {$ h# m
8 m3 F. M: @  t: A6 }
  ;; First we ask the patches to draw themselves and set up a few variables
  \1 S/ ]' y* R  setup-patches
3 _9 j( X3 a( m  make-current one-of intersections1 L6 m' Q3 a, N, `: n" U$ ^3 a
  label-current
1 Q# ?3 Q1 n8 z5 k' j! N) p+ j$ T. z& B2 h3 `/ {+ E( t8 u
  set-default-shape turtles "car"
4 \% T' O9 a# N
7 {& x5 C% c% o5 u3 A/ C9 `  if (num-cars > count roads)% z7 R/ T. t% {
  [9 s$ E' ~) B: q* e, p9 M
    user-message (word "There are too many cars for the amount of "9 ]: e# D, M+ i# O# B
                       "road.  Either increase the amount of roads "
0 c0 m' u/ k; Y  c+ t" l8 p                       "by increasing the GRID-SIZE-X or ". @3 g% k0 f  K1 h
                       "GRID-SIZE-Y sliders, or decrease the "
' o/ a9 H; w8 f$ b. G! ]3 t                       "number of cars by lowering the NUMBER slider.\n"8 N8 F0 f8 e9 z6 z
                       "The setup has stopped.")& c9 |$ y+ f9 c& b" `- J+ R
    stop
2 x- g; a. C$ i( h# {  ]
7 e$ ~+ P: Y  a2 q( m9 }
9 E/ d) t+ t/ P# I  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 D. f3 h  u# {
  crt num-cars
1 N7 z" u0 t3 h) E, v: d8 f  [  V& X3 |( _0 R+ n
    setup-cars
; \$ ^& H' d- o+ P1 E; K1 c4 _    set-car-color* o1 o+ a. ^4 i" p
    record-data
* I1 p- d# F& H% D" U  ]
9 o& `$ t9 i* u1 Y0 ]$ v! C2 P3 Y& t& u6 K* Q
  ;; give the turtles an initial speed
- O$ \3 T! e% N4 ]# R9 W% h' n  ask turtles [ set-car-speed ]
+ s4 h+ ?' l* F" {
% a# U2 P  D: C8 B; V" x  reset-ticks) x1 H: ^9 Z/ @- B7 E1 O. ~# k8 T
end1 g' k5 k5 e+ a; p: N: p

7 K8 y& R: U) B) }; ]2 j# [;; Initialize the global variables to appropriate values. T$ j4 v7 W$ i% x+ w5 t+ T0 o
to setup-globals
- l* ]+ X9 k, F5 F9 g5 o" X  set current-light nobody ;; just for now, since there are no lights yet3 |5 b) W' S- j: K% i
  set phase 0
# z* J, J+ f3 {, N1 l  set num-cars-stopped 0
/ K- U4 H0 @% B8 P7 R* \" {  set grid-x-inc world-width / grid-size-x
6 s& T5 `" K1 R  set grid-y-inc world-height / grid-size-y
" ?  R8 `+ ^1 D3 Q
& u9 x4 }3 u  i  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 s1 U/ K0 ^9 ~; A3 G0 b  set acceleration 0.099* d6 {7 ?2 X% u2 ?
end
& ^  [" \  p; @/ q& ]! v. P2 ]" |* Q% K2 F2 T* }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- T  N! ]; m+ Q6 I;; and initialize the traffic lights to one setting
' }! L; h" r9 Z$ F. t/ M; A2 Sto setup-patches
" k! U! l/ }$ T3 `; Y  ;; initialize the patch-owned variables and color the patches to a base-color9 B4 S, ]; |% l" E4 q
  ask patches# T( u2 S2 o( f& J9 M: R
  [
% Z( k# T4 K* p8 G$ C    set intersection? false
4 L: k6 ?) {2 u    set auto? false
  l$ S4 S9 C" _  Q) V- E    set green-light-up? true% @; i8 j3 B' n  }% s
    set my-row -1
1 R& M3 J% u8 o    set my-column -1/ k6 F8 k3 Z! \
    set my-phase -1
/ Y4 N4 _6 z" ?3 m* ^    set pcolor brown + 3
' c6 g) v4 X: n0 m/ T6 c" U  ]
' t7 O" i$ i' O, s1 v
" L4 J) U3 W9 y/ [  ;; initialize the global variables that hold patch agentsets3 f$ _; v' ?. Z5 ~; E' o
  set roads patches with
2 i7 R5 d- o# D7 n% j, L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 [$ Q1 K/ v( `& P* g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 i$ F( A' u/ p# O  k; l3 H  set intersections roads with- W: [6 E5 a3 ?6 |1 x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 G* w* H6 U" z( H) m7 c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 f1 n$ C+ d5 u5 |' [
/ f) f( d% w6 Y  ask roads [ set pcolor white ]. b3 q5 Y  |/ E% x( `
    setup-intersections0 f0 }9 L; A" \$ g
end' Y( I0 C6 C# E. A! V2 ~6 S
其中定义道路的句子,如下所示,是什么意思啊?
" o" _- R% ?- a4 Q4 I- k set roads patches with) A6 f/ |( k4 [+ @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) t7 D; P) p& B! t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 ~; ]4 N& C& D7 Q$ p. 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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