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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。/ \) |8 z! M/ x" @& f9 |% S/ e. D
netlogo自带的social science--traffic grid这一例子当中,, }" @- B; `3 _) w3 s$ \" W% s
globals0 {+ K3 X$ c7 P/ ^0 `+ P( \2 y4 s
[
8 A9 {# H6 _( N  grid-x-inc               ;; the amount of patches in between two roads in the x direction' Y1 N. K! @  u8 l
  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ F! z9 z# @  ^2 p" T7 z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( Q( q6 [6 L) z! P3 `                           ;; it is to accelerate or decelerate1 |1 [& c4 f# ], M6 p2 v6 ~5 L
  phase                    ;; keeps track of the phase7 l7 U) r- n3 \3 U( y% ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
4 p* m+ q3 Q: j' ?+ B/ d  current-light            ;; the currently selected light: T2 e$ w& _2 s- P  h

" }( J- w. B) i# x1 z  ;; patch agentsets0 g( H3 \6 J2 f, j
  intersections ;; agentset containing the patches that are intersections0 l6 J0 k4 B; k' K5 A
  roads         ;; agentset containing the patches that are roads) G- U! c( C, F* P
]
6 K8 `+ Z7 I, x) k9 z- b! r* r+ Z* c7 C( \5 s- S
turtles-own. m8 H: E9 {9 y2 \3 Q2 H
[" b( F) X. E  n2 @
  speed     ;; the speed of the turtle- O; B6 R. w$ I! V
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: H- a% U, M/ e1 d. p" f% y  E  wait-time ;; the amount of time since the last time a turtle has moved
! ?+ u: j' x! \5 \! S]; X( B5 u5 |& L# j

8 b- [4 Y7 N5 K# h8 y1 a' z$ epatches-own
/ M4 K0 S/ |6 S6 j& y[1 u1 L0 z9 Y" G( W( M2 c, y. Y5 _& [
  intersection?   ;; true if the patch is at the intersection of two roads; T% v5 k3 `- h" f9 K$ Y: J, Y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 _: A9 P2 X  R8 u. ~                  ;; false for a non-intersection patches.
" O# W( p8 ~9 G) }+ k0 `$ ]  my-row          ;; the row of the intersection counting from the upper left corner of the
) l# K* X6 \' a! \( u8 j, [6 n% d                  ;; world.  -1 for non-intersection patches.9 i; q1 R: ~7 `5 w' F  j, d% D
  my-column       ;; the column of the intersection counting from the upper left corner of the7 u  c, x: L: \  `
                  ;; world.  -1 for non-intersection patches.
' @0 W, Y9 j, K3 M  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* l: a: }0 N8 y- l  g: S8 j
  auto?           ;; whether or not this intersection will switch automatically.
+ l7 K  y' o$ c( g' J1 y0 N. G                  ;; false for non-intersection patches.
5 }: V2 s* g1 Y/ C' X" d]
6 D1 R) I, \* W" V+ ^' o1 y& R9 L
) ^5 K: V8 W; s8 N8 g* I
* j% S( I" B5 k9 ^5 I6 L  s! a;;;;;;;;;;;;;;;;;;;;;;, B. c1 D' K' j+ U& }9 a; B' I
;; Setup Procedures ;;
, Z( l% H. G( q( _4 l8 e;;;;;;;;;;;;;;;;;;;;;;# G) ~  A5 T$ u

/ h. c# M, y9 \" n3 E;; Initialize the display by giving the global and patch variables initial values.
2 Q! {# l* o0 d, ^  q4 Z9 d5 n3 x;; Create num-cars of turtles if there are enough road patches for one turtle to
) I8 n" q' j7 h" O1 {, J+ E* I  r;; be created per road patch. Set up the plots.
% n. U/ O7 `$ ]6 O% _/ qto setup) E+ {& P1 z# d3 d; x
  ca
& s- O- j+ r. ?2 C" t0 c9 O  setup-globals
5 T7 [$ A( o# a8 K) u2 b
0 E5 j$ q9 }# i1 V7 |4 |1 ?  ;; First we ask the patches to draw themselves and set up a few variables
: h- {/ Q# B5 Y; ~2 ], |, }* X  setup-patches
/ d- P9 f) T4 c4 K& [. a  make-current one-of intersections3 T* |. e- }" q) U' _
  label-current7 K- k% `$ s* q1 T

3 v3 A1 A# ]8 Q1 _  set-default-shape turtles "car", B3 e! s# J# x" X5 a
! v! o& v$ ?* m
  if (num-cars > count roads)0 z" k" |7 E8 m( ~( u
  [
# v# e4 _% N! e+ y* a/ _$ O6 W    user-message (word "There are too many cars for the amount of "& C; }3 Y7 B2 ?. v, U$ l
                       "road.  Either increase the amount of roads "
4 B0 a) p" J" @6 x                       "by increasing the GRID-SIZE-X or "
; t1 f' W# z3 i' k+ g                       "GRID-SIZE-Y sliders, or decrease the ", n2 m1 K# @$ {( q1 {
                       "number of cars by lowering the NUMBER slider.\n"
1 l$ R" k* {8 g! S8 d$ M                       "The setup has stopped.")
" D* H6 `2 H' s( B6 `" V) [: N    stop
7 i" ]  }4 G/ {+ q. U' R! J; l  ]$ b& S: m! x8 x* B; A) c

9 `8 y  {0 J" a0 x8 ~1 O7 N# C  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color, F; C+ X% F) y
  crt num-cars
2 M9 B; y0 h) \4 @* b% U  [
6 z, U% L( N% y& y2 \8 {% `    setup-cars, d9 U& L  Y& G4 Y1 @6 k
    set-car-color1 ~0 T, T$ [0 ]" h; q) x
    record-data
7 |" q3 ]) ?6 \+ j  ]
" q6 c+ j. S$ d7 m! C' j2 {  [# P6 X4 }. }3 G
  ;; give the turtles an initial speed* \% g# L+ p6 a" E0 t
  ask turtles [ set-car-speed ]
- G  W$ e8 V( U2 Y& \7 ^
/ o3 ?/ J6 {7 V: h+ i. _  reset-ticks# @- c& M8 D( F) h
end0 H: {; M4 Z" E% Q9 b8 {1 N
: c0 V/ i+ n# ?1 U" H  u3 D5 Z0 Z
;; Initialize the global variables to appropriate values5 M/ r( k0 I% a1 p. T
to setup-globals, l3 X% w& A' `( f* Q
  set current-light nobody ;; just for now, since there are no lights yet
+ w5 o! C# p  y# w. D$ E1 V0 w  set phase 08 I; \0 {  E4 j5 U
  set num-cars-stopped 0
# |! t% G4 r+ Z3 P: K  set grid-x-inc world-width / grid-size-x# `: \1 x. J! [7 b, F, V
  set grid-y-inc world-height / grid-size-y! u/ \, Q0 b% B9 E* g: E  j+ o
2 `7 G0 F; x( H/ R
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 A$ |- y9 Q6 s' A" ^* m5 i  set acceleration 0.099
2 I4 F/ N; t$ I$ Vend" ]  m( h$ m9 W4 i  Z7 J6 `( m9 u

0 R  R1 Y  K0 [6 e: L( {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' h3 V- V6 [. r4 I$ y5 N' e3 g;; and initialize the traffic lights to one setting. ?6 B1 [- Q7 k. [
to setup-patches& |, u$ G. V. W+ t: ~7 Q& p" W
  ;; initialize the patch-owned variables and color the patches to a base-color! T, @) r- P1 u9 E
  ask patches$ r* s' z3 f, S' L" H1 J
  [
8 |% A7 Q4 L- e    set intersection? false
4 p) v( o! ^# O# k+ ?    set auto? false
, C4 u4 r  {( P; m0 W: s    set green-light-up? true9 \, m7 K& x- F+ o: f$ K
    set my-row -1
0 l- W/ R! a0 z( ~    set my-column -1+ ^/ ^1 C# z) m
    set my-phase -1
3 M  m' X+ ^5 }7 a( |    set pcolor brown + 34 i# B. J% Z* K! k+ ^! o/ @$ x( m
  ]
0 [% K" E7 b. ^0 W! e- \$ g, P2 Y, o. i( }
  ;; initialize the global variables that hold patch agentsets
) t) G) `  P, s8 P2 j# }) ]  set roads patches with$ r" ?7 j. T/ v9 R1 ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 Z0 v" O9 O$ _0 j! L3 j
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: T# f, Q, R4 @# q# L
  set intersections roads with/ k  q; a, e1 j% E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 C1 E4 `, T7 z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ ^0 t$ L2 H6 r8 L5 k. d
0 X$ Y9 c( W! M/ D9 F
  ask roads [ set pcolor white ]8 j$ q- }+ D. H8 x4 V% l7 }
    setup-intersections
9 {& J/ ~/ c8 o5 Iend# r; Q. ]" T2 X9 N' l4 c1 a9 S( k
其中定义道路的句子,如下所示,是什么意思啊?/ T; J7 ^, ?! ]- L
set roads patches with
0 _: u9 k7 `1 q  z5 n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% P% ?$ i5 P0 c3 S, M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 u) ]" s5 _5 t( H: 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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