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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。4 ~0 l- f% j; k5 w! z
netlogo自带的social science--traffic grid这一例子当中,4 u. N5 S7 ]" E8 r) I& b$ X, V* U
globals! b8 w+ D* ?! F* ^
[
2 ~( {6 ^  B! B; H& D  o  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 p. A2 \* ]+ g1 E" s0 {
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 d( N3 R' y  A. }6 }
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 k3 I4 L9 X9 _, o+ b* J4 G7 N                           ;; it is to accelerate or decelerate
2 ]; ^0 g" N  |  |% z- Y9 T9 J  phase                    ;; keeps track of the phase8 ~3 b& ~' s' t- k( t
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 S* q$ e6 c$ e6 `, B" [- G$ }
  current-light            ;; the currently selected light0 U3 A. a) X6 J0 `0 S! X/ ?

0 A6 g! a( _* E( C' a  ;; patch agentsets, D3 J2 ~- U! T4 a
  intersections ;; agentset containing the patches that are intersections( A+ J3 e6 Z* }5 K0 F0 a2 S+ j! e9 O4 y
  roads         ;; agentset containing the patches that are roads) z8 T3 `# ^8 @9 c9 d
]
, K3 e+ D, m* I: V+ T, i9 e* s+ S0 u2 W; p+ A4 s# {$ N
turtles-own7 w) z& ]$ X9 u( D5 L" h8 s: W" Y
[8 h2 `5 N& l- k
  speed     ;; the speed of the turtle
2 O& X, m% X/ x/ G! X7 w: j! C" f- T, o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& i! b# V3 i, S! P* G: o  ]& Z
  wait-time ;; the amount of time since the last time a turtle has moved
( @3 f$ u) a7 D$ d& l]
' |7 K, d5 ~, r3 u* m5 h' T4 r7 a# J9 p& l
patches-own& C* j( o; e: N& [$ o5 z0 a
[/ F, A, A/ y+ D9 ]
  intersection?   ;; true if the patch is at the intersection of two roads
& @3 V% H  c7 R2 R9 I: E  W6 H; \. R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  A: J1 x  b; I( e! b  D                  ;; false for a non-intersection patches.% H: l! C  N* Z2 n: a
  my-row          ;; the row of the intersection counting from the upper left corner of the) l% v9 D: b6 n0 ]8 ^5 R4 _
                  ;; world.  -1 for non-intersection patches.
/ R8 ]* p# I# A, K4 ?9 ~% {  my-column       ;; the column of the intersection counting from the upper left corner of the
3 v1 R' ~- A9 I8 d                  ;; world.  -1 for non-intersection patches.
" y- B, Y+ K; i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
1 v9 v# w+ z/ l. Y$ E/ e& f  auto?           ;; whether or not this intersection will switch automatically.
( N7 |, a* g) j. o                  ;; false for non-intersection patches.9 D; n/ x7 z# Z3 u; s8 f% U5 A
]" t, Z  Q" {: T& g

2 u& `( T/ a& I6 k
0 r, Z: H. }1 ^7 M" t( k: g;;;;;;;;;;;;;;;;;;;;;;
# ^7 y+ e9 S% ?5 \;; Setup Procedures ;;& ~2 }: t# j* c  }2 z' }
;;;;;;;;;;;;;;;;;;;;;;) a& O2 I  L% Z

1 D8 s0 Z( F) ]- h8 G;; Initialize the display by giving the global and patch variables initial values.$ c- e% g& d. m4 p
;; Create num-cars of turtles if there are enough road patches for one turtle to+ l4 \' p( b( }7 _$ [. K
;; be created per road patch. Set up the plots.
9 J* K4 y+ ~' z5 J( o# Q2 k- c& @to setup! v& o) R7 b. i1 d# ^8 n! p
  ca
" V" u* J# M. v/ D; R  K; @  setup-globals
; M. p7 A; O$ K! v! D; ]2 M- j( Y- _9 G' W3 E! k% A( j: e
  ;; First we ask the patches to draw themselves and set up a few variables
' `+ A2 }6 p3 i/ [) _' }  setup-patches
8 P0 U3 h" |9 ^" O  make-current one-of intersections: v! o2 k% O$ `
  label-current
, r: I- U( k! X: {- r6 _) ]. t- T! z+ M/ B% B* ?' ^
  set-default-shape turtles "car"
1 L- _! Z/ h: g" o* @' I; v2 x$ v3 v! b+ z4 L. y5 q1 M: A+ b+ \4 r
  if (num-cars > count roads)+ K$ L2 @' h. c* f$ \) H+ p
  [1 L$ M" |" D. P! @
    user-message (word "There are too many cars for the amount of "4 I4 n% x% U2 [1 D, W
                       "road.  Either increase the amount of roads "' \' l& O& O* I* o' ?7 K" [
                       "by increasing the GRID-SIZE-X or ". G. r* u: M1 i# R+ D
                       "GRID-SIZE-Y sliders, or decrease the ". L0 h4 E4 x# ]
                       "number of cars by lowering the NUMBER slider.\n"
% ?# e9 Z6 g8 s; J2 b. [                       "The setup has stopped.")
6 O  N$ Q) L8 ^5 G: Q# K    stop
5 O, Z. F  J' |8 N' j  ]
% w# k/ d, o# t- B' Y# E3 [* e8 ~' P: z& o  |. y2 r. P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" \% y/ ]0 g# t0 u; E$ \3 f# i9 k# H- S  crt num-cars  D* C0 V/ a* Z& `
  [4 W( \( T: E; k- Y6 K
    setup-cars5 l: ~6 ^0 L3 }  Z
    set-car-color
- J. u9 {% R1 B& s; w+ d    record-data
% k- x0 ~3 r# e  ]' ?/ x0 A  F+ @$ v+ O

# V4 v, ?$ F; U5 g, `( v  ;; give the turtles an initial speed
- q! z  l" t6 c* \% k6 c- n) o+ e  ask turtles [ set-car-speed ]! ~  Z* H4 b- ]) I2 Z" I6 h
' a8 K8 w5 x6 y$ V/ ~. ^: W
  reset-ticks
$ f, Y7 K7 w% u# L" i7 tend: w; `0 A2 {. }, k8 q& [0 {7 c6 N

8 Q! Y3 `) ]8 h* k# O' e1 P  I;; Initialize the global variables to appropriate values7 w- t9 `4 E+ _. f6 q% @7 ^0 K
to setup-globals
% A7 c8 A$ ], K+ H2 [# m1 C( E  set current-light nobody ;; just for now, since there are no lights yet
9 o  x9 K" M4 O% R; c% |0 S  set phase 0' W" m; i# c4 l8 L- t
  set num-cars-stopped 0
5 ^' n* |, C: h0 T, r' {- p2 m! K  set grid-x-inc world-width / grid-size-x
. z7 ^% `, K2 E9 f  set grid-y-inc world-height / grid-size-y
& H4 i. ~8 E$ E
4 _! p& F" p% T9 d  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 }/ w1 W% b+ J0 b4 ~5 u7 @9 b  set acceleration 0.099
% ]6 T" ^$ q: W, E, B- ^3 zend
$ z/ d: d/ K4 f! G5 ?' D; ]
7 P7 w$ n  V) \* P( a( n! Q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' {) s8 _0 w  _, A* d, J' q
;; and initialize the traffic lights to one setting6 _5 ?/ n6 [' T
to setup-patches
! }5 Q& z) Y4 c0 \: H4 G  ;; initialize the patch-owned variables and color the patches to a base-color7 b, b. C( y7 ~7 M2 B
  ask patches9 }8 `8 k5 ?2 k# N* O
  [  H' i& ^& `7 `6 n  \
    set intersection? false0 d6 y# D, r6 P; o: f# X
    set auto? false
, K/ o1 d/ v& r4 |9 F" q    set green-light-up? true# `/ |$ F/ `# g, T' \2 }2 K
    set my-row -18 t3 t8 q/ w) R5 ?1 S: {
    set my-column -1
7 z0 m/ ]0 b- R6 L: V" Q    set my-phase -1, X' z2 _. L+ L& V
    set pcolor brown + 31 d/ b, c$ p5 C2 n/ g
  ]4 @  R* o# G1 o/ R( z2 z+ G
, e2 `6 h4 s4 B, T+ }  q" Y; s- t9 w& Q: B
  ;; initialize the global variables that hold patch agentsets
8 E! S- O7 U9 K  set roads patches with+ P% D' t( r% p; S6 `4 \  N( b3 L7 K; ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 L, L- ]0 @9 z% j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" Y1 a. U  T# M2 m/ r" W" i7 L
  set intersections roads with# X. ^) y- O. `6 t5 a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and$ c. U; j& D% A2 z0 v* V8 w7 r- Q! A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 r' J5 |/ y3 F4 L8 A
" z7 q) f/ X1 M6 o% y
  ask roads [ set pcolor white ]
- P' Y, g, K, e; u    setup-intersections
9 b( W" `: C* X  o4 R7 aend% ?% z0 D8 a, ~
其中定义道路的句子,如下所示,是什么意思啊?
2 M: _4 |4 b2 L# P. N. ^6 T set roads patches with& ~2 |; R  h3 j
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ [3 V9 Z1 t, A7 ^3 e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 [; D: l& |: j! S, Y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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