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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。3 B- G$ B/ d- ]: H8 n
netlogo自带的social science--traffic grid这一例子当中,3 \7 Y8 ^& ~0 P
globals) `' n4 T( E; D2 R$ v
[
" `7 o* m$ y" N, [  grid-x-inc               ;; the amount of patches in between two roads in the x direction! Q# a/ R4 n% M/ P
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 x$ j- z. p/ z. j5 o5 S+ p  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 a7 R9 w; E0 @0 N
                           ;; it is to accelerate or decelerate
, @" w; b' Q' Y5 C# J6 n  phase                    ;; keeps track of the phase
8 F" S& P: x/ v+ s: J" U  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% X5 Z' m: M. G. w  current-light            ;; the currently selected light; v/ Z3 L) g; c  |" K5 l

; _' y# s( d9 M1 D6 @  ;; patch agentsets
0 {+ Q& F6 {. `8 t, A+ M2 G! e  intersections ;; agentset containing the patches that are intersections
+ t5 G1 [' Q( I* S6 G% Q  roads         ;; agentset containing the patches that are roads
$ j( b  b( \0 o/ f& `3 {# p7 [8 L]$ C8 N; A3 L3 f( c1 t7 _3 R

4 u2 c& |0 b$ w! H; r! G9 @% p/ Oturtles-own, {0 u; t/ a5 z3 m+ h- P: ]2 C& S0 u- x
[
# e! u% E6 |6 x$ f# Z  speed     ;; the speed of the turtle% a; \2 [+ w: K* q5 j, g. r
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" B2 f' U! f5 y% D
  wait-time ;; the amount of time since the last time a turtle has moved) S9 N8 j/ S# [. K1 M7 x/ `" b5 W
]
4 p8 L+ `* I, h" t
% q& z) R7 A: ?: K  ?7 y. v7 Y3 v9 [patches-own3 X( i3 _: m" }" P" V& ]2 V
[( ]3 I5 e4 Z4 I9 h, ]( e
  intersection?   ;; true if the patch is at the intersection of two roads
9 ]' c! t4 Y( T$ D% d  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: Q2 J! C& L# B                  ;; false for a non-intersection patches.
, R" J# q7 {  r. o5 E  my-row          ;; the row of the intersection counting from the upper left corner of the! R) e+ A8 O0 r6 t0 R3 _9 g
                  ;; world.  -1 for non-intersection patches.
+ V9 R+ m' K: O: _) E; E, [  my-column       ;; the column of the intersection counting from the upper left corner of the/ L7 Q7 s8 R2 \& n- o
                  ;; world.  -1 for non-intersection patches.
8 X% i# ?( g/ x( O0 @* g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." E: v1 g: O! z0 h
  auto?           ;; whether or not this intersection will switch automatically.; u) o7 V7 S3 R$ R, D9 @  Y! h
                  ;; false for non-intersection patches.
; ~* Y9 f+ R  \]
2 k: \- R9 @" @6 b; M7 w0 m
4 H3 g+ r7 h5 h( t$ S' w
1 L' [3 O/ u4 K+ n  P;;;;;;;;;;;;;;;;;;;;;;
8 Z5 p7 U! `  I6 {8 x;; Setup Procedures ;;) i# w9 Y: E3 `; ^
;;;;;;;;;;;;;;;;;;;;;;2 C/ q% ]* I" B) i5 M
3 m& o8 N6 o& T5 J% I$ x1 b8 ?
;; Initialize the display by giving the global and patch variables initial values.( x( A% d$ G( h" n4 X7 h2 w
;; Create num-cars of turtles if there are enough road patches for one turtle to
" W/ r, Y# u: V2 k* h* q- j: M* ];; be created per road patch. Set up the plots.
" C9 ?8 G9 E& D+ vto setup
; V; Y8 c/ f  G$ C5 z7 V1 ?  ca; g0 I  G0 ]1 d. ~
  setup-globals
5 E: H  `6 h5 d& j9 ]8 B. p8 [% ~* c; A! Y; g
  ;; First we ask the patches to draw themselves and set up a few variables
# Y4 h& y6 W9 A  t  setup-patches
8 J  t( u! V" d! d! X5 E6 f  make-current one-of intersections
/ D  P& D* g4 i+ x# B4 Z, a7 p  label-current8 R$ I1 }' s3 b2 G/ H$ K! c

$ J5 {8 ]6 J8 \2 [$ J  set-default-shape turtles "car"
5 J1 `. g. x# _& S, j: j0 Y* ]9 x/ o, X& H
  if (num-cars > count roads)( q$ h; L9 A, H9 t' j9 O$ M- {
  [9 K, N+ d: y4 u' o/ Q: s" ^
    user-message (word "There are too many cars for the amount of "9 y& W# a8 e, w, q, J7 l8 Q- S
                       "road.  Either increase the amount of roads "
, T" ]: |) z6 k$ ]: E* w                       "by increasing the GRID-SIZE-X or "
+ |8 ?# Q3 [1 E; I* G' b                       "GRID-SIZE-Y sliders, or decrease the "! u- D& c  f9 [( q
                       "number of cars by lowering the NUMBER slider.\n"
% J+ |4 Y5 `2 E, d- z% k                       "The setup has stopped.")
( B1 X) b  p! B6 a4 ]0 x    stop8 k- o" u, T' \- @" `. u
  ]9 U1 J- U& Y. W0 U8 A% r* Z% r

+ g  y' s9 q2 l! j4 ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 F" o; A, \+ F3 A* w7 e/ {- R$ q
  crt num-cars" g' X" O' n, S3 r6 s
  [
' {0 P2 \; ]9 Z* k- L* z% Y    setup-cars6 }, n! d6 h' a, R8 l2 n
    set-car-color0 V6 f% i/ ^9 y6 R/ e, v6 t' x
    record-data- M$ Z0 k$ E* l. o, ~
  ]
( K% A+ E! V% k; }6 Y2 L
* v' }4 L8 v4 c6 {9 ~  ;; give the turtles an initial speed
7 R! K: d0 z. u/ u  ask turtles [ set-car-speed ]
2 w# C0 T0 p5 W- c  y
9 Q( H+ ^! k1 v: a0 K. E  reset-ticks6 d# C; j3 X! ~# M5 E
end
0 a% J, W9 ~- E1 c% w5 t( I- p0 G6 z% b$ y8 A
;; Initialize the global variables to appropriate values' R. h2 f* l8 @6 Q" n
to setup-globals
$ x# c; j: V( `  set current-light nobody ;; just for now, since there are no lights yet
$ T% z' G  Y8 h  set phase 0% ~3 u  o  W' L1 K( k
  set num-cars-stopped 0
0 X$ Q% l5 V  U8 \( _1 y  set grid-x-inc world-width / grid-size-x
( J7 f: t% F( |, l  set grid-y-inc world-height / grid-size-y
& X$ K6 J1 B" b, P0 i! `. ?2 c
/ s4 W) m$ V6 ~" W3 f" |) W  m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( a& k' y) T8 i! S; C0 f4 K0 U6 b' L
  set acceleration 0.099# a8 L* D& o, J6 i4 @  j3 O
end0 o) ?+ x" ~1 n
/ e; I, s  g' z
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' }$ A1 h1 h  e" n: [3 N" y7 h1 e;; and initialize the traffic lights to one setting
* ~7 ]& z; w6 e. Tto setup-patches$ a; L6 z- r: |. h7 Z2 Q
  ;; initialize the patch-owned variables and color the patches to a base-color+ f# t  L3 j5 d4 {* G" g8 k& B& @
  ask patches
$ T8 A9 Y$ d1 E% W  [
2 H) H& \0 Z" `6 B% \    set intersection? false
+ S" R# ?( \5 b( J' D    set auto? false( L4 D$ e! I4 l
    set green-light-up? true% O. Q$ A# {' g" e: g* M+ J
    set my-row -1. I9 ?0 C2 p( N" r1 w1 h
    set my-column -1
4 z+ Q# a- H4 |; }% Q- B" E1 K    set my-phase -1
& k7 `5 f# p! w) y' ~# Q    set pcolor brown + 3
+ m; A5 g8 p4 l. v  ]$ |+ c" M: {; _& u8 W# `0 y9 }
( @! Y  R8 C6 U% y- b
  ;; initialize the global variables that hold patch agentsets2 V9 ^, n# @$ |& W' t2 [) g8 _2 I! j
  set roads patches with
  s, H8 l( `& d; q$ x' m/ q2 P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* z5 L+ S: l0 D3 [# k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" J0 Y$ S8 r8 L
  set intersections roads with
% d! X+ \  c( q% M! N  v% z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 [% s, Q  f5 E6 ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# S' y+ T$ X2 `! E; }- ~4 x9 h5 @: {' d7 O
  ask roads [ set pcolor white ]" y3 @/ p# K7 G4 x) S+ ^* s
    setup-intersections
, T  U, L, s7 S$ C( S& jend7 y" n; M' V2 y
其中定义道路的句子,如下所示,是什么意思啊?8 ~- M% n& t! [8 |, X6 Y2 `6 ?
set roads patches with1 A3 M7 J" q! y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 A5 M0 {- o( i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 X, U$ r" K0 O/ f; v& L  [+ m0 u* L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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