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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。' s7 v% ~" E3 q4 q% O
netlogo自带的social science--traffic grid这一例子当中,. I$ `) C2 g5 b" L& `+ X
globals
: l3 R/ E( s1 x* J5 U[
6 B$ d, k% [  v# C# j+ n7 O  grid-x-inc               ;; the amount of patches in between two roads in the x direction* ]* k+ T5 o, }
  grid-y-inc               ;; the amount of patches in between two roads in the y direction" X5 p6 d8 ?+ V0 r5 j
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: y1 I0 |7 Q5 \% V3 O& n                           ;; it is to accelerate or decelerate
$ @( N2 u+ u& `- h3 T  phase                    ;; keeps track of the phase
! p! r; d3 o! ^* i; E/ c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 R9 y5 Z# M) J1 _  @! g  current-light            ;; the currently selected light
3 o. C. Z% z: L  @) B* |: U. ^1 d" Q# S. o5 |
  ;; patch agentsets: I4 I; _4 T  L  `5 M, j0 |
  intersections ;; agentset containing the patches that are intersections
5 ?) [% N+ V2 t! e* j) n  roads         ;; agentset containing the patches that are roads
. H( e5 A$ f; M9 R2 L/ j]
/ H* M4 k' t! r* X- u# H
' w" y" }6 P* G" v/ N" Bturtles-own4 E( _; y: h; Y' m5 K# P+ P
[8 d7 N" h* I& ~# O2 t
  speed     ;; the speed of the turtle
3 C. Y' ^: G% y9 p1 O: U  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# z" V# g6 n: r3 v/ v' i  wait-time ;; the amount of time since the last time a turtle has moved
% O4 H3 u7 L$ ?7 P. H; v! v]
! k* Z' I2 q8 m$ c
" D' p0 O1 i# M0 f) @7 L; _patches-own2 W6 L0 _  |- d( J( t/ g* K
[
2 N8 g& o/ ?: N/ r& d" c" b  intersection?   ;; true if the patch is at the intersection of two roads
( C. Q! z' A) b8 y5 {8 B+ \0 f  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  I+ _8 l4 T& e6 d                  ;; false for a non-intersection patches.
+ `' f  ^- e$ j# e& K7 @2 K  my-row          ;; the row of the intersection counting from the upper left corner of the3 o! q1 T# P& w6 q9 W8 W; k  ~
                  ;; world.  -1 for non-intersection patches.8 ]" h& A) ~; K) l8 O# l  W; X, S
  my-column       ;; the column of the intersection counting from the upper left corner of the# @8 t: V/ h2 U6 z( \/ f9 x5 N, Q6 v
                  ;; world.  -1 for non-intersection patches.5 {/ f8 W: \4 H
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  s& N  t$ L. N4 S4 \  auto?           ;; whether or not this intersection will switch automatically., l3 N1 J3 A' k- q* h
                  ;; false for non-intersection patches.' R3 I) [. b6 B
]
9 Z: x9 |) ~: V5 M+ `! v( K% I$ f; H- t% n" Z
) q4 U7 M1 N$ d9 s2 K) R
;;;;;;;;;;;;;;;;;;;;;;
2 C% L% O4 k7 i7 s;; Setup Procedures ;;
5 J9 G- u9 [' L) d4 I4 |5 n;;;;;;;;;;;;;;;;;;;;;;
: c" P$ O+ h6 ~% @/ g9 O% }
9 g$ U2 [3 N  V8 f# W;; Initialize the display by giving the global and patch variables initial values.* f0 z, w! m; B# F
;; Create num-cars of turtles if there are enough road patches for one turtle to. T2 Y) I; y* e; Q+ M. u
;; be created per road patch. Set up the plots.
, t9 U; J9 j! \/ b1 d$ S+ Y# Ito setup4 E6 \: _# {5 d) O- g# d
  ca
9 v' U5 q! \- o  setup-globals1 e4 `2 V. J3 n( N7 j7 M

9 h; r5 I! L7 z  ;; First we ask the patches to draw themselves and set up a few variables* ^* D0 b! l, o% H; M, j6 Y! z
  setup-patches2 U5 A+ L/ t: Y: K# k/ g# B
  make-current one-of intersections
  }8 M% p6 o% [) j) Q# g. N  label-current) ~7 m. D8 ]  q7 ]9 y7 F7 U

" F5 e4 s9 T0 o6 _! q, A7 e# `  set-default-shape turtles "car"! C" S$ C* d. _2 d7 j

: j/ v9 h1 S, a  if (num-cars > count roads)9 Z) Y( Q4 N/ l% P1 s1 d8 E
  [
% s7 y' I; U' l* j4 s4 v    user-message (word "There are too many cars for the amount of "
7 b6 @9 a& J8 W# i6 k" }* E                       "road.  Either increase the amount of roads "
  V0 u5 J6 z' G) ~0 z2 X                       "by increasing the GRID-SIZE-X or "
) p9 s8 @( v  i* H) d                       "GRID-SIZE-Y sliders, or decrease the "0 w0 L2 D5 }; i4 g9 f/ m1 z
                       "number of cars by lowering the NUMBER slider.\n"
7 b  O* D8 }: H+ I                       "The setup has stopped.")* h6 Z2 J+ V: x* S
    stop
. H' X0 b0 }( }  ]
+ ]4 Y/ @7 M% ^  t' P3 J( e0 B; w. ]3 ^. v9 z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# A8 ?. [. p, D) b* ^# M3 ~
  crt num-cars
6 y9 ~& Z2 A, o9 O  [
0 h) }0 M  q( J    setup-cars( X( D$ e/ G% L7 |$ f  O
    set-car-color
/ ?" n, j$ h3 D+ H! p5 T8 t    record-data( g, J* j0 {$ C; A* r: z- _! N
  ]/ P  r6 g' b. f: n7 b

6 f" ^6 }$ F6 F8 C' ]7 P  ;; give the turtles an initial speed7 s) P- j- O) b) N9 |4 I( @3 k
  ask turtles [ set-car-speed ]( R  S) A( \* s8 ~' D: Q
9 R2 m3 D  X) V7 G
  reset-ticks
' H0 y7 p. s/ n/ ]! [6 Pend
+ m' t2 n! F  E; N; o9 y" Q, l0 R
;; Initialize the global variables to appropriate values' l. C& M3 r8 S4 \* v3 K& T# t; o. Q
to setup-globals7 m! c$ f4 ]) Z: k+ a  M
  set current-light nobody ;; just for now, since there are no lights yet
- Q3 i& j5 j2 y# s2 n$ \  set phase 0
6 w3 K( j, B9 \! d5 x  set num-cars-stopped 0  P: L  w. [  x5 z2 F
  set grid-x-inc world-width / grid-size-x  f* o: H$ n2 x
  set grid-y-inc world-height / grid-size-y
. P& h, r) |4 s/ |! s6 M$ J! z; F2 r: G4 F. l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ q& K# a- u% D3 Q$ k, K' o  set acceleration 0.099
: `1 C5 R3 `4 h5 G+ }7 c( ^end
0 e' U) }8 D" g' n7 K
8 v( ?# K9 L/ K;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
2 U$ _7 S6 e5 P3 @/ I" C& y4 M9 E;; and initialize the traffic lights to one setting$ B7 q+ {3 Q- E) S5 f0 p, N' ]4 U
to setup-patches9 Z- B$ Q) Z! J- x% N% d
  ;; initialize the patch-owned variables and color the patches to a base-color
$ @% r( L! |" B! k7 _0 Z0 _  ask patches1 k: s" C( s3 ^; l7 x3 s! K! F
  [/ Q& S, e" _# X& k
    set intersection? false' d) y8 d7 R& Z( r8 H# O) i) W( @0 h
    set auto? false! O9 ~7 k0 w/ z* v9 V
    set green-light-up? true, v. q9 `! {7 q# L: k
    set my-row -1
7 P0 C+ L, W" C! ]+ H. ^% D2 p' ]    set my-column -1' l& b' }- O" ?8 w5 u
    set my-phase -1
" a* o( M- t/ O    set pcolor brown + 30 J# V  T( @# l/ j
  ]
: p1 h9 J: T; }8 o; M
8 _2 i5 j  L/ v  ;; initialize the global variables that hold patch agentsets
. J" o) k$ d- e4 R. _/ v  set roads patches with7 V% l* b& r6 J5 _# t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. j! |& C  k) d" ?6 M2 f7 X0 i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 A; W; g8 A2 Q' p4 q  set intersections roads with: k) Z- h' ^1 H3 O/ O1 v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 l" G* G. I# }$ N( [- Q& N: o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% M$ B7 U0 y. N1 w9 f% Z0 A# v
  p8 n; Y7 R1 [  ask roads [ set pcolor white ]: }8 @. `$ v- w' v$ q2 ~/ X1 _
    setup-intersections% y* S0 J# _. q; \. S9 v
end( F7 q  Z* P" ~; S) K+ [& L' h
其中定义道路的句子,如下所示,是什么意思啊?
. R) _4 T3 w+ {( F1 T% R set roads patches with/ n2 H" C. W0 P+ ~- x- Y/ F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* H$ u! p" E: D+ j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 `, l* V8 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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