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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。$ V: K) g0 T# u7 g; S
netlogo自带的social science--traffic grid这一例子当中,
7 T/ C$ b6 [! [6 d* g, b' h' F+ {globals$ x5 |$ A( @5 L$ \( `) [) S& S6 H
[
7 D$ G% Z+ w7 M% G  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ }( x  z% @/ [- \1 |6 z+ E
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! f6 {1 Q; _6 B3 o9 T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; X* j2 C: O( w- H' H
                           ;; it is to accelerate or decelerate3 }6 l2 ~8 R* E  q- j
  phase                    ;; keeps track of the phase" U" t, c, ?5 K
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% l( m6 Z8 y+ p) c
  current-light            ;; the currently selected light% s6 o5 v8 J% b$ g

. P2 p2 O  ~" L/ a8 x1 p1 `) W9 p) U  ;; patch agentsets, F  k# z4 |! \1 `1 u" u
  intersections ;; agentset containing the patches that are intersections
( x" \4 T9 M# H$ N2 k  roads         ;; agentset containing the patches that are roads
& ~7 L! r1 ?/ H% n7 |  |* d# _/ F]
/ [8 C( w/ ~1 e4 D2 I; ?' z
; I/ ?2 k% |# [- i* H4 Pturtles-own9 V7 b, g# E* o1 ?
[
/ M8 t* k) R* A' h8 o. j  speed     ;; the speed of the turtle
; g/ t& T! h$ t; S, W3 n1 {  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 Z1 A% P' F& I; \& [+ f
  wait-time ;; the amount of time since the last time a turtle has moved1 V! ~* k/ P6 h0 F- ^
]8 L3 w7 z' n7 A

8 {  g# I3 }" }- |% s: opatches-own  W' U0 B* W: S2 @3 {' p* |8 |  W
[' k6 O- S' ]) o  u! V
  intersection?   ;; true if the patch is at the intersection of two roads- t  M5 G( w: W; ^1 B/ \
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# d! c" o! h7 a: R                  ;; false for a non-intersection patches.
+ `; S8 M9 X5 H: \+ W  my-row          ;; the row of the intersection counting from the upper left corner of the- W9 j3 B4 h5 t# I, p$ V# p+ H
                  ;; world.  -1 for non-intersection patches.
2 H8 j1 Q" S0 G5 U, k6 l. V& p* K  my-column       ;; the column of the intersection counting from the upper left corner of the
: i1 U- u4 Y0 k) r( n; k  D4 }# |                  ;; world.  -1 for non-intersection patches./ F: \0 w; e! B# g8 A' q: W0 K
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
5 e) j6 w$ b  P0 x  i. L4 |  auto?           ;; whether or not this intersection will switch automatically.; o( @4 }+ c1 Z( u7 e7 Y& k
                  ;; false for non-intersection patches.9 U3 f+ i1 w  I) `% I! A4 t$ W
]5 i: d1 k7 x5 s( a  d
5 X8 y! |" e- g
2 o( b: j4 s/ P; H3 c+ M- B: s% K
;;;;;;;;;;;;;;;;;;;;;;
( A$ H' I: k. O# d: g7 h3 a;; Setup Procedures ;;
4 p6 C+ C2 C2 W! B6 ]- Z;;;;;;;;;;;;;;;;;;;;;;
5 Q* \& z% E: u% [. D/ H$ s5 |! y9 I: }6 c; G& \
;; Initialize the display by giving the global and patch variables initial values.1 r6 p, k& ~2 ~  w
;; Create num-cars of turtles if there are enough road patches for one turtle to
( u1 Q% e1 u5 W! v;; be created per road patch. Set up the plots.
0 `( N% F; D% ]) L5 c2 {/ Xto setup
; I4 E" ?8 W! I# @  ca% N& J* H" e  h; ?
  setup-globals
& H1 g1 _$ D- `: g! q! K1 x+ L* F! \  W9 {1 }
  ;; First we ask the patches to draw themselves and set up a few variables
# X- M' ?2 O! J2 j& E  u) O  setup-patches
/ r- X, a& F4 E: Z' e" i  make-current one-of intersections
, g2 g. i7 W( w9 k  T# {& h$ ?  label-current' r4 b9 h" \) c. ?" H8 M

6 R; N# ]8 J6 T3 {' c0 |  set-default-shape turtles "car", o6 l/ g  R7 u3 L  T& n, A5 w# I; k
% y  S! @# p* m1 u- `
  if (num-cars > count roads)
/ M- C' b" Z( H- ^% p  [
& U/ [, H4 q' q$ {3 v( ^    user-message (word "There are too many cars for the amount of "
+ _6 r; x- \0 x5 t% B                       "road.  Either increase the amount of roads "9 ?" m- T* W4 |  D8 L; f# t" A  h
                       "by increasing the GRID-SIZE-X or "/ E# o1 S3 ^  \) _. G  r" ^2 h9 h8 u
                       "GRID-SIZE-Y sliders, or decrease the "
: B* a- W. Z# p; c* x                       "number of cars by lowering the NUMBER slider.\n"
$ Y* G7 `' |  y: G8 I9 B) ?' u                       "The setup has stopped.")
6 v: i+ q) X8 a4 u1 A) q& z    stop
& t# E4 x4 D1 D# k: O, C  ]0 @% C6 P6 f8 @

8 u" e) O! ]' e# b* O6 v9 D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 I9 f; M2 w6 X: d4 L5 q  crt num-cars
2 e( [& c$ M, [  [
  g& D0 [( O% h9 e5 J. {& Z' u    setup-cars
6 b5 j) t7 S% w9 W$ W# M: q    set-car-color
7 j9 Y! j2 z2 y    record-data
! U- p" _3 T/ R  ]- r: f6 K% i* A- l$ G
* O3 d# S1 {5 _" ]3 v( u' `6 e
  ;; give the turtles an initial speed  G4 H; V4 |  P+ Q* F* v0 L5 z5 ]
  ask turtles [ set-car-speed ]6 F4 `8 B0 G0 \, T$ S0 p  G- W% t
! @5 K' ~- ~3 @1 z
  reset-ticks& E  ?+ c) j  R  ^$ [. B: n
end
$ ]* m5 w: A# e, W. g& b5 {6 S
- a9 `. s, y  v1 [) x+ Z; u" z6 z;; Initialize the global variables to appropriate values  m, O% p: u  w0 q) }
to setup-globals9 M, e. I/ {8 e. N
  set current-light nobody ;; just for now, since there are no lights yet
2 P* j2 E; N" s8 J; ~5 [  set phase 0: S7 k& g4 ~4 s; k5 U
  set num-cars-stopped 0
/ V' L, }: m& S# }# G# }8 \: \- a  L' L  set grid-x-inc world-width / grid-size-x
& M: R, d1 }& }3 ~  set grid-y-inc world-height / grid-size-y
3 A* x6 A6 p4 B
$ e: I* W- k+ i1 b6 g6 {" l  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary' \8 ~, ]+ H# ]( }
  set acceleration 0.099& S0 F5 h2 X7 C/ B' p4 C8 q' y- \0 I+ d
end4 }. @5 G  }, e! D

5 I" M& d) h* ^;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. \, ^$ o( E# G2 };; and initialize the traffic lights to one setting9 l/ @* Z# T% b& }9 I4 A; K
to setup-patches
. F2 ]  ?# m. H  ;; initialize the patch-owned variables and color the patches to a base-color8 E, `! O" R: ], t% q* S
  ask patches/ Y2 y- A7 \% T; U" d9 T2 \, P
  [8 c" M$ x+ F; ]7 b5 V0 K
    set intersection? false* c% L/ `. E4 q; p
    set auto? false
9 D5 [4 l6 o' t. u7 u    set green-light-up? true
# w) |2 A" R; m8 T; H$ b1 ?    set my-row -1
  q) {# ^6 W, I9 Y& _9 u% v    set my-column -1. {4 I4 \  |9 r/ c, X( l
    set my-phase -1
7 L& J7 m' f2 L% y4 _    set pcolor brown + 3
' R5 P7 D  R# i6 ~  L* U: p  ]6 D5 F" r2 \! @" `5 N$ U9 W+ }
/ J% R% Q4 p6 \; J4 h) n: G3 R# @5 I
  ;; initialize the global variables that hold patch agentsets
3 A/ B. ]0 \) ~1 r  set roads patches with6 H/ o! `# v! ]7 S' f7 J& x  k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# M. q0 |2 D; B' s4 z$ w$ z9 m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* n, O9 Y" g  t& D. i# C  set intersections roads with
$ U% L" j9 O8 o2 |    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- o) k4 V& I7 o) W- t) F+ j) k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# G, j9 f' {, A1 C% \2 U
9 z0 Y) K$ s0 S$ v  ask roads [ set pcolor white ]( p! |5 o  o+ G. B9 }% v' o
    setup-intersections
  q, o4 O  H- gend
5 r, T8 G( Y9 y' E9 k9 _1 \) c! f/ \- _其中定义道路的句子,如下所示,是什么意思啊?
7 U) M/ k9 V5 ~+ Q( l" h set roads patches with
0 j; }, \+ `6 q) }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 U! T+ X. }* B5 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# [1 B0 B5 Y9 P! L! X) C+ 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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