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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。& a- N- E2 ~2 u, @9 u- G
netlogo自带的social science--traffic grid这一例子当中,4 O* j- L$ M! E5 u" C
globals
4 \  X: A' _$ U  s" e# ][
; L6 @# _& Y3 l8 ~2 R3 U  grid-x-inc               ;; the amount of patches in between two roads in the x direction& l- H% R# B" k
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ f- @% v) T8 q9 x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 [6 I% r- u9 Q                           ;; it is to accelerate or decelerate
$ q8 I, ~3 r5 t' s5 ?  B4 H8 f  phase                    ;; keeps track of the phase1 E. K$ Y% l3 I9 }
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
) J1 `! ]8 J# O* B+ W  current-light            ;; the currently selected light
7 s5 ^! K6 E. `8 _
7 `; U; d- ?& D3 Y& M: L  ;; patch agentsets; h( Q8 E& s1 T, L
  intersections ;; agentset containing the patches that are intersections
  m4 T9 T* ?1 S1 ~# B- I: ]  roads         ;; agentset containing the patches that are roads
% n' O7 S5 Q' t7 `; w. V" G]
2 o( M9 C$ I. |4 s. }2 Y& `6 M! n- }- Y! p
turtles-own
6 u$ A- M* ]; h- C/ t, Q( |[
1 m' }/ o& {4 n  speed     ;; the speed of the turtle
9 S: o& i) g) O9 n, o8 M  up-car?   ;; true if the turtle moves downwards and false if it moves to the right1 h8 u+ w3 d4 k6 |2 p
  wait-time ;; the amount of time since the last time a turtle has moved
7 |- @# C0 U1 y& x6 g7 c, _$ A]/ m4 Y3 A* T' P' S* D4 n5 D9 j

( l* u- a4 l) Z3 u3 Wpatches-own
3 f+ G* ~+ {1 }' R[0 |1 A) y3 I3 s4 {( ~1 p1 h1 k
  intersection?   ;; true if the patch is at the intersection of two roads
* \& e1 p, A) i1 ~4 m5 J  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
$ J9 r/ z( @0 [5 P                  ;; false for a non-intersection patches.
  Z7 m$ `2 f' D* H  my-row          ;; the row of the intersection counting from the upper left corner of the; f! _% l+ R+ Z" K
                  ;; world.  -1 for non-intersection patches.
2 D) b% D  g. B; I  my-column       ;; the column of the intersection counting from the upper left corner of the
& a5 A+ v: R1 }1 k; B                  ;; world.  -1 for non-intersection patches.
4 M* p; w. [$ n6 Y% O  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- J5 X# R6 J8 P3 B7 ~" a
  auto?           ;; whether or not this intersection will switch automatically.
$ m- p6 F  Y# r' U& D  F( A) p+ U                  ;; false for non-intersection patches.
& t& v4 g# d8 ], F5 ^  d8 U]5 g* B9 U8 S6 I# Z

& d2 E6 ?2 r# O" i& n/ ]) u
+ ^% w2 P, T" c) R' ^0 E: H- K;;;;;;;;;;;;;;;;;;;;;;
+ n. Q8 c, r) [# Z3 _8 o;; Setup Procedures ;;; i  u7 q( \2 e9 h: X$ M' ~
;;;;;;;;;;;;;;;;;;;;;;
- e  s* h& P. V- o
" Q# i" y! [* g- J# _/ J& {;; Initialize the display by giving the global and patch variables initial values.8 p- [1 _6 a; w* X9 C
;; Create num-cars of turtles if there are enough road patches for one turtle to! @: z2 t6 K4 s  k- R. [' y
;; be created per road patch. Set up the plots.
$ ~" J4 j2 u& q8 _% @' N# vto setup
) n4 K6 ~/ ~& G5 T  [  ca: E9 M1 p: N/ Z+ k8 K% I6 j7 I
  setup-globals  k0 L) m$ }. x
9 S/ K" `7 g. f7 ~7 A
  ;; First we ask the patches to draw themselves and set up a few variables9 ^" L% M* ^. _
  setup-patches: }$ b7 @: h6 x2 J9 j6 `* A
  make-current one-of intersections
0 A1 j+ N: e/ H) `  label-current
  x2 C) p7 V* y4 H6 J8 Z
# y! z7 p  O6 \/ w  \# t$ @  set-default-shape turtles "car"1 s% s. e1 C- i& g! k
4 z1 S# X! _9 _6 G" M$ F/ j
  if (num-cars > count roads)
$ r* S7 ?( H' I; _  z  [
4 U. h$ U: k6 a, c) |* U    user-message (word "There are too many cars for the amount of "
  C& ^$ a( \2 R0 Z. r7 F                       "road.  Either increase the amount of roads "/ v* J2 e# D1 ?7 i8 D7 [
                       "by increasing the GRID-SIZE-X or "
6 D8 w& @# ~& f2 B# u9 B* s                       "GRID-SIZE-Y sliders, or decrease the "
2 L, p1 |9 p* w1 G/ B# j7 P' M7 f                       "number of cars by lowering the NUMBER slider.\n"+ K6 p8 V+ h# r5 q# e  h
                       "The setup has stopped.")
( d6 [9 ]% o1 m8 v  i    stop
, b7 ~6 c9 G  T1 A& U* w  ]1 F" G& C- _3 a% q
0 G. ^4 V  ?* `+ T2 g. ]& U
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 ?) P- [( t: T/ i2 ~  crt num-cars
9 C6 |# ~% }, A; j9 @  [
8 U6 y+ s: k! Q5 A    setup-cars2 x8 e% z" H6 p3 R. ^+ T
    set-car-color
1 W" K8 T* s; ]6 e* K: ~. j    record-data5 P# I9 _. U7 b/ z. X
  ]
, i0 p# P' A* }/ R$ `8 f* Q& d
" x/ Q# n4 i- [$ H1 k1 C2 X  ;; give the turtles an initial speed8 }' Q. e4 p( F( Q. Z4 [  e
  ask turtles [ set-car-speed ]
- v3 ~5 E& H* {2 ?+ E  c+ z+ }& ?# d2 Q6 b. v
  reset-ticks/ H5 E2 r3 S2 v0 \: T! A1 Q" y
end
+ x7 U2 P2 i- v# y7 d5 w/ x2 g( H# i  R- g8 ?; Z& d0 F: W% _
;; Initialize the global variables to appropriate values8 k' n2 K2 f) f1 W3 H, d4 t4 m! G
to setup-globals0 l# C8 n3 l9 u. B) N7 T- j- j
  set current-light nobody ;; just for now, since there are no lights yet
  k0 @8 T2 e' k. I5 j  set phase 0& ~3 ]* @. N; A4 y8 [
  set num-cars-stopped 0$ k  Y( E9 i& A
  set grid-x-inc world-width / grid-size-x& t! ]! S. L! v
  set grid-y-inc world-height / grid-size-y6 u( I) g5 @4 S. s
9 @( ~$ y" H, d3 }& I, x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary5 }. a: _  W/ J" `
  set acceleration 0.099" w( ]0 G& B1 |
end& m" R, B( p, e

) k7 I$ L$ e7 a1 B7 T8 N6 r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 H- u; Q& h  d, I
;; and initialize the traffic lights to one setting
1 H& F# F7 Q2 B9 [! p; \8 vto setup-patches
4 l" r' u6 R. Y  ;; initialize the patch-owned variables and color the patches to a base-color
. o! Z/ e, [  q4 ^1 v! [- k: W  ask patches, P! M6 Z3 ~9 B' R" D! v- R- c
  [
& Z# i7 }8 C( r* W    set intersection? false
0 Q5 y0 i" _3 j8 i8 K    set auto? false6 P" W6 k; |; q/ E% {
    set green-light-up? true" O+ m  m6 B4 k! T
    set my-row -16 l. j  p- I+ C
    set my-column -1
" i/ _! Y0 I5 o# u  x1 P8 N8 A! L    set my-phase -1
) a8 @" d; U  ~7 b    set pcolor brown + 3/ y' U4 G' @: F+ _3 o, i
  ]
! b! c# u6 W! A
% B, Q9 ^3 {  g1 s  ;; initialize the global variables that hold patch agentsets
+ X! P9 e0 t: M0 ?# i  set roads patches with+ _! j3 m4 }+ H7 L& ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 Q+ f0 q: f) N0 n7 f5 I* o4 ?8 q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& k$ q, E. Y% l4 v! z
  set intersections roads with  v" s8 i4 e; x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, U; m* J* V# @# y3 z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 {+ G6 H. i5 n% q. o/ g
2 m0 \, M: e; ^4 y4 N3 M  ask roads [ set pcolor white ]
  u0 [% E, N' |    setup-intersections/ \  w; L* X& ^" T
end! ]/ C9 j3 o$ J: r1 w$ @
其中定义道路的句子,如下所示,是什么意思啊?
% c$ v9 X- I& p  O) C set roads patches with
& p; _3 L( m! T* a$ p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 B# \% G9 W; }' `& z. S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ K% k0 j5 B- S
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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