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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。. q2 ]2 z1 H7 ]: W$ J5 ]2 q
netlogo自带的social science--traffic grid这一例子当中,& _' ]7 a- x# A1 p  }# ]
globals
; s$ j9 D# [% G/ M" w+ k& _0 S5 D[
* n! N0 D& b. o  grid-x-inc               ;; the amount of patches in between two roads in the x direction* V# K; N6 E/ h$ _5 Z4 H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 O# t# P/ ]9 |
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 h, E( y3 @! }; \4 v. @! c
                           ;; it is to accelerate or decelerate
+ s) G* S$ {, Q' ^0 g; A  phase                    ;; keeps track of the phase
+ q0 c2 C9 m9 U: v: I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, k7 u1 Y  y/ }' V  current-light            ;; the currently selected light6 X# m/ S$ X& `1 Y( @
" X0 ^* M- i8 T4 l
  ;; patch agentsets0 x' X, T" P1 @9 E  l
  intersections ;; agentset containing the patches that are intersections
7 V) _  Z, V; @  roads         ;; agentset containing the patches that are roads9 `5 i+ \1 ]' Z! @
]
! K6 n' h0 M9 I( h& [) ]& V- [* e  L9 g
turtles-own
% D# p% U( E) U$ w[
3 g; V4 o; R6 d7 `7 ~- t8 F  speed     ;; the speed of the turtle( g' a5 H" C' c" r+ E
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" N9 `6 A! H9 i3 z- C1 x: B8 j  wait-time ;; the amount of time since the last time a turtle has moved
4 V% ~2 D  M1 T/ b% Q]
! [; F1 Y2 A9 q. w4 ?; A9 @: R$ n! k; T, c- p
patches-own
/ ~* A+ T. _1 s; b. t[
2 i7 H2 u( r5 J% I" |  intersection?   ;; true if the patch is at the intersection of two roads
7 D2 N2 _( P' O9 p2 \" A  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; A( M* t; I+ p! D5 x; s                  ;; false for a non-intersection patches.
& E' W( S' Y3 k2 o" U' p0 S  my-row          ;; the row of the intersection counting from the upper left corner of the, g4 I0 x3 ~& I2 g
                  ;; world.  -1 for non-intersection patches.$ r* [9 D, l. v+ w; [8 ?$ L* |  U
  my-column       ;; the column of the intersection counting from the upper left corner of the
, @) U% ?4 r, |3 G, S. v                  ;; world.  -1 for non-intersection patches.9 Z8 P5 Q! N3 U( ]* ~9 S' o: s7 ~
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% z/ G# N: l3 h6 x2 E8 J# f" S
  auto?           ;; whether or not this intersection will switch automatically.# n1 a  q" T6 {# \
                  ;; false for non-intersection patches.
- K! c2 O0 T' T) F8 R8 u  j]. J6 c2 o  ^8 V  R

9 R4 w1 t% U! l; v' }  N6 O  |
' Y: j. W2 o" j( v' v;;;;;;;;;;;;;;;;;;;;;;5 j, f- g. N3 o$ W& G" Z' P
;; Setup Procedures ;;/ W% L- v# {2 `: [! O% A* n
;;;;;;;;;;;;;;;;;;;;;;
' m9 c/ x, U; `
( J$ d( b# T& z% i& R$ e;; Initialize the display by giving the global and patch variables initial values.
' `; q* u$ k1 D8 p;; Create num-cars of turtles if there are enough road patches for one turtle to
  ]- x0 q6 T% ?( y+ d;; be created per road patch. Set up the plots.$ ]9 _6 y( U+ e$ N8 e. ?
to setup$ B  b' I  [, S1 C
  ca
( ]& F& q/ f7 t4 ?" j  setup-globals/ z7 E3 Y  I$ H3 [4 m

) M9 t$ g$ c! L  ;; First we ask the patches to draw themselves and set up a few variables7 v* w. u$ b) c8 _/ B
  setup-patches0 J3 u' Q) d2 A
  make-current one-of intersections
! G/ M. M9 S3 Q6 J' |6 B" `  label-current
* K; ~9 k1 t% _, [8 a) B6 I7 O% l
6 h3 e; }! o& w' i( O. n  set-default-shape turtles "car"
5 N) g# W; p7 t- }4 u& t  {! m* l8 i# {6 s
  if (num-cars > count roads)
7 F( ~/ t. `+ d  [
: I. j6 a0 j, s8 }/ ?9 r0 F+ V4 \    user-message (word "There are too many cars for the amount of "
; F7 O8 J" V8 c$ J8 H2 Q- e4 T                       "road.  Either increase the amount of roads "
8 F2 z0 V8 l: A: d                       "by increasing the GRID-SIZE-X or "
* L) e6 K5 ~+ s+ z+ D                       "GRID-SIZE-Y sliders, or decrease the "# U  F# m# Q3 }: j. [- B$ V& |  w
                       "number of cars by lowering the NUMBER slider.\n"
$ H+ N# {; G! I* N                       "The setup has stopped.")8 l) }) v% c0 ~( y. q
    stop
& o1 D0 x7 u% C+ R7 F' `2 Y  ], t) S0 ^, G2 f( x' r
( d' j8 q, G& @0 l) O* }( I. E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' w$ W# w. r2 v/ K: R  crt num-cars7 l, w  r" j) b6 S2 V
  [1 K' M/ o6 i( G( i4 e6 Q4 Y
    setup-cars4 l, F1 F( [. b2 [4 q: Y
    set-car-color" }& V( R8 z7 d% x  S
    record-data
, L1 u, l; P9 }  ]. {2 U' ~) {; O- ~6 E; C; O
$ [) ^: f" O! u7 o6 E; K' X
  ;; give the turtles an initial speed
! N2 {' `  O4 m, r/ M/ l  ask turtles [ set-car-speed ]
, l/ S/ A; V8 p, g  s) U, D$ S8 U# ]7 C7 ]* o0 l8 O
  reset-ticks
" w8 f, L2 i" h2 w' K+ }end
0 r3 B6 N1 d7 Z0 ?' {4 M, \. t- i3 u/ B! O; g
;; Initialize the global variables to appropriate values  R0 Z( d; B% [' n6 L2 l  F
to setup-globals
0 P# }) m6 ?3 l; E6 r0 C! x9 @  set current-light nobody ;; just for now, since there are no lights yet9 r; O% f. M9 G$ w# i4 R& l
  set phase 0
2 I$ T3 i$ p) _8 t  Z8 ]  set num-cars-stopped 0
2 y7 d4 E$ u/ H- H5 I  set grid-x-inc world-width / grid-size-x; z# j! l+ j3 a& D' p8 g
  set grid-y-inc world-height / grid-size-y
1 `9 W/ v3 R' o$ S$ R
+ a$ C4 r& z" ^7 q( P& l. q% y2 }  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 v5 x. ^/ M: H4 x+ p  set acceleration 0.099
+ m8 h9 G3 q) r# C4 Yend: a2 }4 \9 q+ Y& q2 m

& E3 g0 T  G7 `8 X* {' k" d: y* N;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! R+ Z% ]' S% a; q2 v- ]) L2 k;; and initialize the traffic lights to one setting' x! O- z% E1 N$ j
to setup-patches
' G$ B5 }: c! `4 H" Z8 U# d, c  ;; initialize the patch-owned variables and color the patches to a base-color( h# H$ W6 t, q3 C, a8 a
  ask patches7 c+ n) n, ]! B  I0 H
  [0 o( A# `, I: |
    set intersection? false# W5 r# J- n/ o+ }! h
    set auto? false/ S; y: l5 O' @& O9 {
    set green-light-up? true
  D% i4 i/ C) z0 c. `' j    set my-row -1
: `2 S* b$ V) m2 [    set my-column -1
! t, f6 i% Q6 S" K! g. I3 M- {    set my-phase -1
& f6 i- H# K2 c# z" y" a    set pcolor brown + 33 A# L4 R4 Q+ Q, b
  ]" {# G, \/ c. R% T# h7 V4 }: D

; V3 N0 q9 ~2 J" l  ;; initialize the global variables that hold patch agentsets
% |6 c4 F( r1 ?* a* R2 O9 C  set roads patches with1 A8 @- Y7 J5 w0 q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 w5 g5 z- T* B& B; [3 E* Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 {! ~$ Q& H1 D! M6 p+ J
  set intersections roads with
0 `0 z  T( r+ h$ w& o/ l# q: N4 c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# g1 B5 N) d$ n9 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- M0 F) u: J4 G: a' a8 f" p
; E; w- w4 ^+ P5 \5 g
  ask roads [ set pcolor white ]1 e; q# ~1 E" Y+ P- a/ p" b$ W: {
    setup-intersections
5 \- ]1 G! i5 L  b$ W; Oend
! V' P, s/ ]4 W$ {其中定义道路的句子,如下所示,是什么意思啊?
) L$ {# ]* d: t! c0 ^+ @  O  I set roads patches with
4 J3 F- `, e! l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ E/ k. Q' L6 `5 P% O! n$ \7 R8 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- X5 x5 z- m. R9 a6 D" r
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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