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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。
. H7 S8 F  \- H) i! @, pnetlogo自带的social science--traffic grid这一例子当中,& r5 I3 g% |" T7 g' j9 m
globals) B- D& T& |, i/ q9 R
[
3 `& l% @! A1 g' a' i& z  grid-x-inc               ;; the amount of patches in between two roads in the x direction- q7 R$ w7 c; o* \" ?
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# G8 l" ^, o$ B5 \) Q9 j
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ m; F. E" X2 g' A( n
                           ;; it is to accelerate or decelerate
! U' ?5 v( ~8 o  phase                    ;; keeps track of the phase
& T2 A6 y6 H3 ]3 A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 y1 h- N% Z9 k( O4 G4 O% Q  current-light            ;; the currently selected light+ H$ b$ |# Q  f
3 _# r3 B; M0 c: a  V: K) p
  ;; patch agentsets0 [' i( T/ Z5 o7 h( R: g1 p4 J
  intersections ;; agentset containing the patches that are intersections
  s; I# j$ i, p; [5 k) y  roads         ;; agentset containing the patches that are roads3 `1 H% H. o1 A! J
]
7 Q* `# \6 H, d3 a0 Z1 K5 r, F6 y2 j. D; n' p6 `% W" w6 n
turtles-own
; U0 f% i$ j# m" G8 l" D* Z* ]' ^9 W[
1 p# Q" ^5 J  S  s: L) F  speed     ;; the speed of the turtle" c+ e' R" [7 q: X/ T, K7 U( W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* j8 q7 T& {$ V, Z% ^0 B/ h5 y* A  wait-time ;; the amount of time since the last time a turtle has moved
, L0 q3 U1 m' k7 L* i]
, p) g& F( ]7 }: h- s) n+ A% `2 `, p  L1 o7 |# S
patches-own
& V- x; V& k  [5 |; y8 K[" [3 o8 e) H6 H9 z( |
  intersection?   ;; true if the patch is at the intersection of two roads" @3 y# @3 P8 U7 B. R: F
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& Y' u: {5 K+ L! u, ]                  ;; false for a non-intersection patches." J1 ]0 l" s) w7 m) i! e# `
  my-row          ;; the row of the intersection counting from the upper left corner of the
- s3 m% \* E! l; s/ G                  ;; world.  -1 for non-intersection patches.
1 g4 ~( B( B+ S7 K  my-column       ;; the column of the intersection counting from the upper left corner of the9 e& A' c! m: W) z: Y/ e& F- p2 g3 m) c
                  ;; world.  -1 for non-intersection patches.6 Y9 E+ k% H3 ?3 Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
7 Q; e% U$ v% A4 X" `% I  auto?           ;; whether or not this intersection will switch automatically.- V4 |$ t/ T* O) n) @
                  ;; false for non-intersection patches.
% L! k+ h; }, k9 V# ~]& S& @2 Q6 C) E9 \: \3 T

$ W& L( ?* _( X
2 t4 s# }/ Z+ x. V;;;;;;;;;;;;;;;;;;;;;;9 q7 h9 g$ w5 w4 M- D
;; Setup Procedures ;;* p2 u$ [$ |& e% D
;;;;;;;;;;;;;;;;;;;;;;- @- B( n* V  [: I. A5 k
6 o' U! K" @+ }
;; Initialize the display by giving the global and patch variables initial values.: X! O3 b+ s' q4 N  e+ M
;; Create num-cars of turtles if there are enough road patches for one turtle to# o7 ?+ r2 p+ e
;; be created per road patch. Set up the plots.( z! r* T: q' _" i
to setup; y4 k) B2 M2 }' Q
  ca
' h3 E8 [6 ~$ g; S5 R  setup-globals9 B5 Q+ a2 b8 j( |2 B7 m
; g; ^% s! ^6 w8 u! K# E
  ;; First we ask the patches to draw themselves and set up a few variables
+ ?" g# ?* P4 |  W* {6 N* t: ~* J  setup-patches( Y/ [, m9 D" I
  make-current one-of intersections
$ d% m: i: i8 }" z+ L9 a0 c: A  label-current
* I/ N: F, e9 b$ T  M) r/ \+ Z8 R; w) }
  set-default-shape turtles "car") w% L8 U4 A. n8 m9 D
& @( [  E& j. d5 X+ J8 N1 N
  if (num-cars > count roads)
3 u$ ~' L* d  y8 m+ v# J2 D7 V  [
: e8 S3 k. O1 u8 c% [3 B    user-message (word "There are too many cars for the amount of "" \- ~5 U1 v: k* H+ f: F. e
                       "road.  Either increase the amount of roads ": \6 u5 U0 m, Z0 f+ G: {
                       "by increasing the GRID-SIZE-X or "
# e3 g( {: H% `9 ]                       "GRID-SIZE-Y sliders, or decrease the "
; X; h9 q; j% S' c" I                       "number of cars by lowering the NUMBER slider.\n"! g; W. F# }: R3 G% d4 a4 w' ~
                       "The setup has stopped.")
2 I4 W# o9 D9 [, _    stop" P# Z  x# [& a0 a4 C+ n
  ]
' A6 L6 [) ~0 o$ A+ k% G; n: u3 U
! n* k" O) v  M' U  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: J- a- o' S: ~* F* G
  crt num-cars" K* p+ y( B6 E; [
  [  h) d. |8 w0 y5 u: W; f
    setup-cars; _3 d. X0 L% i3 ^; J+ ~/ o0 d
    set-car-color
- `/ B4 c4 O" S    record-data
+ {0 T- p3 X. \' c  ]
3 k9 C, z; ~0 ]' W5 [
9 ~* L8 }, w# s9 ?  ;; give the turtles an initial speed
. P) {0 h- ^9 G1 t  ask turtles [ set-car-speed ]2 L! W: Q4 B( M
/ f4 I* J" G+ ?% F: u$ E; j
  reset-ticks( z4 y0 [! e) I8 a; y) t, q7 k% J  E/ Q
end! b) {8 A: _7 l% A" Z; s( g" U

$ X2 i' G2 m7 d# x& F;; Initialize the global variables to appropriate values% w/ Q( c! e9 {6 _/ V
to setup-globals% i6 R/ D+ p# n/ C9 j4 O
  set current-light nobody ;; just for now, since there are no lights yet4 M6 @. v! S' O$ J
  set phase 0
" t6 s" i: M6 {: A% }: L0 C4 Q/ |) G! s  set num-cars-stopped 00 L6 J  ]" c2 g$ K. o" t
  set grid-x-inc world-width / grid-size-x' i: Z1 P4 K" \2 l/ p* U9 I4 U
  set grid-y-inc world-height / grid-size-y
2 v3 Q+ f3 C) y  [5 K
0 u/ s2 T' {, g  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 ?* C1 s. q" ^+ M  W- {2 `( q2 k2 h  set acceleration 0.099
; D1 ]; v0 C3 r( @# B% U. M2 xend
% ~% M5 q( c: `) G9 j4 r; I& t; H8 F
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* `" `3 a: i% x8 w. }! w;; and initialize the traffic lights to one setting
  z; E2 O( g6 x# P9 W% xto setup-patches- s3 I/ g1 A$ C) V7 D) V
  ;; initialize the patch-owned variables and color the patches to a base-color
% S0 y; @; Y3 v  ask patches' \% i" w$ ?5 C6 ?9 J) [8 q; h( ~% z& w
  [
/ A: m8 Z( P$ E, ~" r5 w    set intersection? false8 d% [! |4 D# ^" F
    set auto? false
6 l9 c( l) W: X6 q. Q9 T+ D! Y    set green-light-up? true
' I7 t$ p8 ?& C% x0 Q    set my-row -1$ u% }; {7 D3 {7 ]6 j4 v% Z
    set my-column -1
; T8 i. X. `1 s    set my-phase -1. R0 S2 |5 I% W0 d& ^
    set pcolor brown + 3, v; {$ R7 ~! o; G6 @) k
  ]- x6 q) n! T- l) Z* R( f9 Y

& N# m3 H- x, U+ q2 f  ;; initialize the global variables that hold patch agentsets
1 D4 ]- a5 x, ^1 c  set roads patches with
7 z" w( d7 ?% j) s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( q7 E8 a: e" a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* @4 I3 }  z' L+ ?
  set intersections roads with) H& j$ d* p) g, H8 H' b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 o" P' i& @3 X4 ?/ W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) B, x  J1 t4 g# x4 ^, Y8 U
7 U4 u& a0 k: s! Y# R+ U* b  ask roads [ set pcolor white ]
, K4 k( d# l, O1 k. `, C3 q    setup-intersections
( Z; Y% s6 ?0 F4 j% _end
: p& Q1 M/ T/ l0 X其中定义道路的句子,如下所示,是什么意思啊?6 ]5 @; @, a. Z) r$ ]
set roads patches with  z( H% i& Q7 q$ r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ b! i3 d+ x+ B- n4 x; O" z& i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" E1 r: S; v' e9 g& N" e3 W# N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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