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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。; h1 o' i' C' R: _, D. q! f
netlogo自带的social science--traffic grid这一例子当中,! g6 y4 a% }8 C* ^/ R/ _+ K
globals5 K8 ^  K% n0 d- P$ n# n
[  u- Q" z, Z7 F7 z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 P9 |/ u# F* O- h" ]  grid-y-inc               ;; the amount of patches in between two roads in the y direction6 M( @, ?( J" F; C* m9 Z/ _
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; d- r; d* t; W* e9 w! u                           ;; it is to accelerate or decelerate
. K/ I6 P' o1 C6 p3 Q- c  phase                    ;; keeps track of the phase, `3 U1 `; M* X+ C3 V3 E4 S1 [* \
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 S" N) R5 X! q" V+ V. P8 u8 f. [  Q' P  current-light            ;; the currently selected light5 g* Z; Y$ G" f3 r: Q

+ [4 T4 z; V9 l0 T/ Z3 D. Z  ;; patch agentsets
" L/ E2 J, c/ u% l  intersections ;; agentset containing the patches that are intersections- Y- S$ ^9 o8 s+ d9 L
  roads         ;; agentset containing the patches that are roads
1 Q# v5 H" k# C, {& q: \]- _7 O2 @$ Y3 W/ K# c% B; j! w4 G6 w
) n% A% A( h+ c$ D" T
turtles-own9 `" {9 S+ d2 q: P
[
" n% _# A; _/ p2 F6 b  speed     ;; the speed of the turtle
" E& m/ u+ |" E& e" ^1 N8 O  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 n# n1 {* Z' Z1 t2 Z: N! p
  wait-time ;; the amount of time since the last time a turtle has moved' I- i2 H( J( k! s; N6 y3 X
]9 j# \  O4 {1 I& P

2 g' W8 U# S: Spatches-own
" Q4 X$ Q5 A! R4 P- a; M[3 W: @+ k% s8 U* o  C
  intersection?   ;; true if the patch is at the intersection of two roads9 e) H8 h- v3 n0 ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# c7 n. d2 G  p( g5 W; M+ V9 _                  ;; false for a non-intersection patches.  Y: g4 n$ E: }- @! ^
  my-row          ;; the row of the intersection counting from the upper left corner of the) O1 l# V* T  p- q# J& F' ~$ o6 Q! w
                  ;; world.  -1 for non-intersection patches.4 C, X- D9 A. A
  my-column       ;; the column of the intersection counting from the upper left corner of the- R5 W/ S+ @. Z1 {% u
                  ;; world.  -1 for non-intersection patches.6 r% P2 K( A$ G, c( @& f
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 `  n/ Y' y) p+ _1 l# `+ X
  auto?           ;; whether or not this intersection will switch automatically.+ z5 e  J- x6 X2 I8 P: K' e
                  ;; false for non-intersection patches.) U  ?9 E3 l- Y' U- U4 K$ S
]
( p9 a9 [6 F/ {) ~  O' [5 ^1 l  u, ~& B, \

' S* G8 l4 }' M  E( b" o; [;;;;;;;;;;;;;;;;;;;;;;; O$ J0 I* {0 c
;; Setup Procedures ;;  b$ m7 O* L% H$ Z0 U+ L
;;;;;;;;;;;;;;;;;;;;;;
9 b* {$ ?6 e+ q# D$ k6 I, A! ^2 w
' U4 b$ w) ]; `( F& \;; Initialize the display by giving the global and patch variables initial values.
: g0 J) Y# K& ?;; Create num-cars of turtles if there are enough road patches for one turtle to
  m" V/ {4 U1 I% k2 a;; be created per road patch. Set up the plots.& _4 @9 W0 e! `6 e7 W' Z
to setup
' _8 f7 g+ |" c) X+ E  ca5 B/ \( `5 ^/ o. z& [
  setup-globals
$ l; i) l9 E' f( ?
* }" c1 `2 J8 e0 M5 H1 k8 L  ;; First we ask the patches to draw themselves and set up a few variables2 J" t! V  e7 m/ O& |
  setup-patches
  a6 t1 e! R7 ~  make-current one-of intersections
  u( e# |' j# b  label-current
( T% [! q. v. o& }) `) s# L
- ^5 m  U& @) T( b  set-default-shape turtles "car"
4 P' P8 d, f/ w+ ?$ q9 n. K
( `& \/ ^/ g) T; R$ I6 }3 i  if (num-cars > count roads). b) {% _6 \/ a% [* R
  [
- B8 d0 h( a& z2 M9 \    user-message (word "There are too many cars for the amount of "1 {" Y' {, U5 s! F* {3 n
                       "road.  Either increase the amount of roads "
) I+ y1 k" k1 g/ {: x0 c/ H7 u* J/ W                       "by increasing the GRID-SIZE-X or "
0 I) f' ]* Y6 i                       "GRID-SIZE-Y sliders, or decrease the "
7 V. U3 K# j. T& O                       "number of cars by lowering the NUMBER slider.\n"2 |: o( l: q8 S  r/ U
                       "The setup has stopped."). k1 {* g/ x$ e
    stop
( |" G- @0 x2 C7 s+ W  C9 j  ]4 }9 E# N1 V0 v: n) r# r
0 ^; `# l1 c2 {% A0 q
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( E. {& O" M# Y! `( S! H; N8 X
  crt num-cars6 v: M" {6 [3 [: u! M2 S7 B! b
  [
& D+ G/ M0 j3 Q4 K    setup-cars; K5 Z% m" ]* S
    set-car-color
, l8 @6 c3 v' t" R    record-data+ l$ b, ]8 c2 X  Y
  ]% _: v* q1 L; ~' T6 V6 w- O' ?
1 m$ ~: y/ M: A0 f( B% |: ^  V
  ;; give the turtles an initial speed5 K; T. c( c9 e2 |* t: }! i
  ask turtles [ set-car-speed ]
% f. J; O; b, ]: t7 Q# z& t$ p
/ e) |- q4 w: S2 [  reset-ticks
9 o1 H( }9 N$ h% s3 Z) bend
- \: M0 h9 m  x2 |0 P% E. ?. a( ]. I& s
;; Initialize the global variables to appropriate values% c- m, G, k+ U( `" O
to setup-globals
: [+ p# X) o* w/ B/ b  set current-light nobody ;; just for now, since there are no lights yet
/ c0 }) k  O: u" S: M. |: l7 W& z, N  set phase 0# ?* V- K; t$ m
  set num-cars-stopped 02 K: @# p7 a+ R4 c5 q% U( J, g
  set grid-x-inc world-width / grid-size-x$ K4 h/ |2 @" k8 \7 z
  set grid-y-inc world-height / grid-size-y0 [5 y, S/ f, L; W

: L5 A1 x3 r& b  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% Y7 D/ R; R; ?$ C; R  set acceleration 0.0999 S% J: B6 S( H1 k/ z0 j2 L- |7 @
end2 z4 F* n& r# I: k( E- a8 B" N6 k  A  O

! M) r) i- _  m; O. k2 d+ };; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: ]* @/ S5 F' _1 a7 p" \7 M- A;; and initialize the traffic lights to one setting
- ~: X5 K5 d. e( `. h! tto setup-patches* y7 W0 c, s2 e! J5 O# L& d
  ;; initialize the patch-owned variables and color the patches to a base-color0 n9 F$ A) ]. K& J; C
  ask patches" n3 p# M3 m; ?8 U6 _( x: \# S$ x
  [
# {$ V  @9 {+ s  Q2 m/ N. P    set intersection? false" g: U, \( {4 B. l( x
    set auto? false0 h* @! j9 _( N9 I5 Z- X
    set green-light-up? true
  M5 m" ~# W" x) A& n1 X3 ^3 [    set my-row -1/ g# _; N: I& d1 U* @& q7 X& U, W
    set my-column -1
- u0 Y3 P- y* F, @' T    set my-phase -1
' }" [$ B4 F; g8 k- {6 e    set pcolor brown + 3
. \2 R+ I: V# s7 o) E* ?8 M  ]
' F# K# Y7 ]4 S' L: Y0 U/ G
  H: W# x1 Q/ a; @" ~7 w% H  ;; initialize the global variables that hold patch agentsets# T0 d' c2 `4 z, ~
  set roads patches with
! v/ W, I8 z2 `/ ?, C6 A/ e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 K) b8 L, W- }' j    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; f3 ~  g3 N% P3 X
  set intersections roads with
' }6 Q$ ~8 T% H: k! p3 j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. i! E9 X. q( M! Y, z% G2 l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& A4 }9 Z9 ~( ?% C
. R) C9 T, D. g
  ask roads [ set pcolor white ]
1 ?$ A* D! r! B, ]    setup-intersections
2 j7 C- z' j4 w5 ?& l. H1 eend) ]: m, m- w& R3 O  I+ Q& S
其中定义道路的句子,如下所示,是什么意思啊?
3 J: m2 @) j9 _! m4 q) y set roads patches with; v  z4 D1 {; O: \& T- d. G7 z! B& v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, e3 z9 z! k- M7 ?    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- [7 ~' U' k" ^( d5 O
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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