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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。& f0 P+ R4 |9 o0 K2 c4 {6 J( N
netlogo自带的social science--traffic grid这一例子当中,
2 ~5 r$ X# r& \' w/ J$ Tglobals6 }% h6 Q! e# V3 N: C& Q# q% \
[
8 I9 t" R$ _* C  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ L. q; J& D' M  @+ _6 X( O
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 {8 j- I; M) p% Z1 B# H
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, v- U9 @7 U6 a
                           ;; it is to accelerate or decelerate3 b5 K" X  T0 m5 h) F4 y- }- E, @
  phase                    ;; keeps track of the phase7 C  @5 p5 f" l& G' b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ Z2 H; T- I7 \& J. {  current-light            ;; the currently selected light
! r8 ~  A/ z  G+ ?- t* E
4 N7 o; c) x6 c1 Q% B6 R  ;; patch agentsets
, J! s6 I2 w3 K$ g  intersections ;; agentset containing the patches that are intersections
( @( a" E4 L- D  roads         ;; agentset containing the patches that are roads
; s+ i, a6 e$ a" L]8 j1 Z# E/ ?3 z
8 Z) S" t, n6 n3 ?
turtles-own, a, f) ]4 f1 p6 i
[* l, q$ V# ?* n3 _4 K; b2 k( r5 W* U
  speed     ;; the speed of the turtle' B! Q" E3 B( w/ K3 `. W( n
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 r1 g! Z8 m! P9 z  wait-time ;; the amount of time since the last time a turtle has moved3 @2 s6 d3 l1 `) K$ h1 w% e4 @4 N% ^
]6 x0 s+ u' V* k# r0 r
! o" b. z! e, [# S/ k' o% B) ^& N: Y) c
patches-own
/ {. m# g6 v$ F. M* ?% m; t1 I1 ?[% ~# F3 O3 D) f6 f5 i9 X* a
  intersection?   ;; true if the patch is at the intersection of two roads0 a2 Q. y# L! z- Q7 F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' R' ?7 i5 ^, `5 u* o( ~$ h9 P* d
                  ;; false for a non-intersection patches.& X. G- e/ }. O$ }/ ~
  my-row          ;; the row of the intersection counting from the upper left corner of the
  L1 t1 Y; H$ _4 R, q! W                  ;; world.  -1 for non-intersection patches.& P, S1 S# d1 ~! Z
  my-column       ;; the column of the intersection counting from the upper left corner of the) B* J; X7 t, p% j$ Z/ V2 Y* Q
                  ;; world.  -1 for non-intersection patches.( y' V$ Q. g; m: l( J1 C" E" f
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" T( g( d2 m# M9 B# U  auto?           ;; whether or not this intersection will switch automatically.
# [; {1 u; S1 q5 A, C5 l                  ;; false for non-intersection patches.
0 b3 N: F& l- P! q  _9 F]
& M3 H. l" }/ C
! X4 v2 ]# ?! K6 l6 {
% @- C. K" f9 L) p% f;;;;;;;;;;;;;;;;;;;;;;) _2 E+ n7 [; [7 f- f: O
;; Setup Procedures ;;
1 Z7 n+ K; n9 G% L3 U" @* V;;;;;;;;;;;;;;;;;;;;;;
- Q6 K2 s7 j  ?* s/ C; b+ @/ E
* X4 J" |! B8 g: X9 K; |1 j;; Initialize the display by giving the global and patch variables initial values.4 I- M4 t2 N- n  G
;; Create num-cars of turtles if there are enough road patches for one turtle to+ E5 k, T' z+ Q/ i! }/ Z" l$ \
;; be created per road patch. Set up the plots.
3 a: F% ]2 _) n, `- N" V" n6 @to setup) k. s' ~. h! Z9 k, i
  ca- }' }6 L. }9 A/ {) c% v* m0 [2 D1 Y
  setup-globals
5 j' I& ^4 d1 K0 S) L
6 o8 c; Y: p! o  ;; First we ask the patches to draw themselves and set up a few variables( Q$ V2 A5 b( ~* m- |) L
  setup-patches
; m8 @' m+ W+ R# z3 D  make-current one-of intersections/ ]& |: Z0 ]& r8 z
  label-current1 j3 d! A5 d4 S, P' R

3 d- j& D) d( X% v  set-default-shape turtles "car"& I5 ^7 X3 d7 e+ @/ T
' k+ n* x, A' a+ O$ G" c6 ^
  if (num-cars > count roads). n3 i  u6 N  Q/ g, O
  [
. S/ n9 J0 W9 l2 f# r  S, i# ~    user-message (word "There are too many cars for the amount of "5 h! q; s+ M* K) a4 Q
                       "road.  Either increase the amount of roads ": q* t4 V' w! ]- v+ J$ k2 B1 T
                       "by increasing the GRID-SIZE-X or "9 z9 S* a' B+ z0 p7 B1 a( A
                       "GRID-SIZE-Y sliders, or decrease the "8 X+ c6 i: o7 Y" N8 r% h0 I$ V
                       "number of cars by lowering the NUMBER slider.\n"
: G- B9 U7 r- S9 j5 Y4 d5 P" _                       "The setup has stopped.")
, N2 I8 \8 ?0 a    stop( E4 F0 k+ k' I4 V; V! z8 p
  ]2 ?/ l  c! L* O$ F, p: G. G' d0 \
; t9 [; g: ~; z  h2 d( E; T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% x* }! G7 n" \$ {; r) f* c1 C
  crt num-cars7 H$ R! S1 e4 j9 Q8 L
  [# ^8 x% G# n: E3 Q8 \  O; O
    setup-cars0 W1 b3 t% _' {1 B/ G
    set-car-color
' X. l  m  @$ S% J4 a: h" u% T    record-data2 F# X; F2 X3 U$ a3 B- t( W
  ]' Y; c( ~4 |8 |$ V) Y; A9 R

: z; w% x" o1 a( ]8 K9 \, l  ;; give the turtles an initial speed
* P0 J7 P& Y" i0 }  ~9 b  ask turtles [ set-car-speed ]$ ^9 S5 V# C& Y6 I9 |/ ~

7 v/ q8 A& U0 y$ W9 l! W1 I  reset-ticks9 _/ m1 U% g8 K7 ]# `3 y$ \
end5 \  x7 P6 n% c* s. Z

- @% s- A3 i' u  U$ c5 G0 x" T;; Initialize the global variables to appropriate values5 i& W* D: x, U4 @' g
to setup-globals
2 i% w) M4 _$ `( P% i  set current-light nobody ;; just for now, since there are no lights yet: a8 L5 y, b9 X2 n- G0 J, p6 e
  set phase 0* p+ A; \  l: b/ K' B4 O$ {
  set num-cars-stopped 0
# K8 |- a- x  m: s* v! l+ A, s; e  set grid-x-inc world-width / grid-size-x
0 ^0 ~  Z$ a% \& M0 {" J+ ~  set grid-y-inc world-height / grid-size-y5 j8 A1 {  R- J3 m- U! j: `9 e( x
, Y; v" g& o! o. P2 a2 {4 p5 u/ l
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 I+ r6 g# _5 w9 g. x  set acceleration 0.099# q* v" ]8 k+ C' ~( ^
end8 {  f' B8 ^5 y6 K( c9 ~6 q3 G
1 p4 ^& w: Y" E; |
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  c6 Q" {" F6 ]# i+ T  h0 r;; and initialize the traffic lights to one setting
+ ?7 N5 i, N. A2 {; Dto setup-patches
: L1 U2 l4 @7 d* @8 X. `, t  ;; initialize the patch-owned variables and color the patches to a base-color
- H: v9 j% D' g  ask patches
1 c: P# S2 M' a8 s- F- O2 t; T1 F) T! W  [- K+ |0 Y/ N, K) `. [- m
    set intersection? false
& X$ A" s/ s" C. k" ^! Q# \    set auto? false
0 l/ H$ \8 A; c2 [' m9 j7 _; p7 h, K    set green-light-up? true
) z& ]4 E; z9 p" X$ @1 C    set my-row -1
/ q9 x0 w/ X: c6 A    set my-column -16 A- E* }" ]9 T. V6 q( I9 v1 x8 {
    set my-phase -15 M  H8 c4 C& k$ ~5 s. j
    set pcolor brown + 3
# y6 z6 \$ p3 y! Q9 ?: p, Q  ]
1 S: N. _) f3 V# ?1 O& y7 T! a& Z2 l+ X2 D
  ;; initialize the global variables that hold patch agentsets3 u' L- e/ {/ K) G1 B
  set roads patches with: U0 l8 e) X- z* W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 W' L9 j# g4 J# z; X* l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 p+ K) g( W2 C- f, q7 r  |  set intersections roads with
# w( ^( F0 V* `7 l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 Y" j8 T. ?/ R4 c; J4 I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& i: F( ^7 B8 a% g* p  I; s4 A2 Z2 z+ F( `: |# ]0 G4 F
  ask roads [ set pcolor white ]
/ D/ f8 B0 w! N$ z6 |    setup-intersections
& V) @0 r- Y# c* ^7 }4 B5 r2 wend! T( z' |$ f8 p
其中定义道路的句子,如下所示,是什么意思啊?
# ?* e$ Z# c& t5 @  v: ~. C set roads patches with
- H: l' t. C$ L% f. m2 g( ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# {& N" @' w9 ~7 y: |9 L1 F3 f; w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 F! K& V: X4 e8 K+ f) M' b- G8 E
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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