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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。; z* y7 w4 l  t6 \
netlogo自带的social science--traffic grid这一例子当中,  G4 }* q3 @! r7 F
globals3 G: T# z* N' C5 N
[
' V. y" E, r9 S2 Y0 x$ p( \  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ V7 i8 J; Q4 U: E. E" V, f0 B  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 M! X, R8 F( j7 Z- J9 p7 E& p: C: f  acceleration             ;; the constant that controls how much a car speeds up or slows down by if) z+ a, C! v) j: \8 f; ]. L
                           ;; it is to accelerate or decelerate
0 @9 ~4 X) `3 R2 U  phase                    ;; keeps track of the phase
# S; V) y2 e3 c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! J1 r: D  \6 K) A! N
  current-light            ;; the currently selected light1 G6 H: S+ e- {% O- Y( t
$ l0 M9 Y/ b0 h: P( {$ t. S
  ;; patch agentsets
( s. i; f+ a0 z8 r2 ^  intersections ;; agentset containing the patches that are intersections
# W- D/ @# u$ u  ^' F1 p$ B  roads         ;; agentset containing the patches that are roads, L5 ]3 z. V3 [0 c
]
2 x( q: [/ Q1 t( h4 ?
# @0 P0 V' f! Xturtles-own
# M' v9 P* R+ O[2 n" U+ J0 n) Z+ P3 Y
  speed     ;; the speed of the turtle
# n9 U7 L& w( K: f% Z1 u6 b& G( F  up-car?   ;; true if the turtle moves downwards and false if it moves to the right) Q4 W6 i+ R4 h# N0 m3 \
  wait-time ;; the amount of time since the last time a turtle has moved5 s' t* a; [" c5 G& H
]
) _; R! C9 `% P# |- u
+ W+ o9 `0 }5 X7 f" Xpatches-own
& H; b  e: q5 k  q$ }* h[5 T0 `( P9 y5 Q
  intersection?   ;; true if the patch is at the intersection of two roads# {0 C( C+ E3 F9 \" w
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
% r! X- N, y5 E, J7 S# K1 _                  ;; false for a non-intersection patches.* b* B- c2 n! p9 {
  my-row          ;; the row of the intersection counting from the upper left corner of the( l. ]; P) ?5 O, q, p1 ~4 |. s+ C
                  ;; world.  -1 for non-intersection patches.
! I' D4 U, C; j8 J; W" C  my-column       ;; the column of the intersection counting from the upper left corner of the  m" s. O; |5 y2 y# A
                  ;; world.  -1 for non-intersection patches.
7 d. G9 j9 p+ [4 v  {  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
6 w. ^$ X; B/ `% M* l/ P  auto?           ;; whether or not this intersection will switch automatically.
: {7 \2 c2 o+ `8 t                  ;; false for non-intersection patches.
5 v) W4 V0 {. _1 M' w- ~]
, r5 W& v5 U$ G  Y- u( w  j
$ i, `  X( g# q5 Q, t" P
4 w& A" C6 _& ]: \1 G, ^& _; c;;;;;;;;;;;;;;;;;;;;;;
3 f, x/ s* g2 m7 P" T6 r;; Setup Procedures ;;8 P+ f3 U5 m- M5 w% B# ?- A7 ^( Y5 T
;;;;;;;;;;;;;;;;;;;;;;9 r. _1 C: D2 t0 @2 V
' _) p0 t. H/ h7 v+ f
;; Initialize the display by giving the global and patch variables initial values.; [$ o1 }' S  C7 f, c
;; Create num-cars of turtles if there are enough road patches for one turtle to
2 X+ J$ ]! `' z. w8 J;; be created per road patch. Set up the plots.# w: U% D: \& A7 T
to setup
# @9 P1 [9 T  L4 [5 a  ca! C3 U7 k3 d7 u" e" q
  setup-globals: i* {- D1 U; Q1 ~# t

! A  k( F) _% G, L7 J  ;; First we ask the patches to draw themselves and set up a few variables. k) w. C, y- O
  setup-patches
. X: @: |1 w5 s' ?  make-current one-of intersections" F3 H/ }9 o; H
  label-current
4 j& X/ A: T) b6 i3 {9 t+ I# _
% P  h: W  P( i- e  set-default-shape turtles "car"  v7 o6 S. p/ I0 s! u9 ^5 @- M
2 P2 e# E' E- }; I" ]7 N
  if (num-cars > count roads)
) y8 a% K2 J9 C1 z0 ?( e  [- j! E# v) `2 L; m, x8 G% S" u
    user-message (word "There are too many cars for the amount of "
& v6 e4 S& {- ~5 O4 u                       "road.  Either increase the amount of roads "
' [' W' z! S1 e& g1 n% Z                       "by increasing the GRID-SIZE-X or "! y0 N1 N/ c3 U
                       "GRID-SIZE-Y sliders, or decrease the "
- f$ J1 i; p5 K9 |1 Y+ s; U                       "number of cars by lowering the NUMBER slider.\n"' r/ Y0 b) u" {3 s% o- B5 C
                       "The setup has stopped.")
6 F9 B) F4 g  J/ f2 L: J) e/ g    stop
+ F0 ?. v- ^6 J  e! N* f  ]
- ]* w% n2 M* ~* r6 B
2 z: l; q/ Q( Z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 d% ^4 @( }9 |: w
  crt num-cars
) C7 s1 T6 w' K8 }* F' }  [
; E5 o/ e6 y0 v    setup-cars
4 N8 Y3 ~9 H; Q9 S    set-car-color
$ Y4 K- T! j$ E: }* q. e6 h1 E    record-data
, ?' m/ H& v1 @" r! B- v5 \  ]
, v% h4 U6 z) ~' w5 X' ?$ g& T9 A, \/ M" I' q5 f& F* [0 G  P$ v
  ;; give the turtles an initial speed
6 m8 u0 @" m, x- b! G$ N+ b  ask turtles [ set-car-speed ]2 _- E/ z) r6 y1 ~0 q+ k$ T3 J" J
' _3 {+ v" ~) r" y
  reset-ticks0 G! s% p6 d. o  m
end
9 t" w2 i$ r- K+ b! v& M6 l, H  a- D7 w! D4 W) f
;; Initialize the global variables to appropriate values% k4 S3 A/ Z3 B0 }, x9 J
to setup-globals
3 a  ?, M0 v! r( H& o) ]/ [  set current-light nobody ;; just for now, since there are no lights yet1 [3 A. c2 D( M; ^7 z) A
  set phase 0; m2 f) N' d; j% ?
  set num-cars-stopped 0
& }) w) O; f8 D: c3 ]: S( J  set grid-x-inc world-width / grid-size-x
4 ?/ L4 }- z: E9 K  set grid-y-inc world-height / grid-size-y
. U/ y1 }8 g, e; F/ H% X9 @" A
. r/ j5 C' [1 T$ C  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary& @$ M. _, e7 r: L
  set acceleration 0.099( |' L, j  {; }- m/ K
end
  q9 M7 V: g0 l, C# j, \8 t. j& }/ \$ G: ]3 @" S/ Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! Y1 [- \  |' L;; and initialize the traffic lights to one setting
" K6 u6 T( C. H( ^8 Mto setup-patches) d+ A8 F/ j. ~
  ;; initialize the patch-owned variables and color the patches to a base-color
/ f5 o% P: Y4 [; @  ask patches  T$ @1 g' H$ K- }. ?6 H
  [
4 v# E- y% l; _/ T8 t: n( k  J    set intersection? false1 @# _5 T8 x! z; D+ B& R
    set auto? false
7 f; C/ j5 U! W8 W3 b    set green-light-up? true
% e# p7 q' ?0 ?" x6 ^2 F/ x    set my-row -1
) r5 f' Q* X6 ~: |/ c    set my-column -1+ f4 A5 u1 }' n  O/ {9 m5 w3 f0 U
    set my-phase -1
1 Q" N1 ~% `/ w    set pcolor brown + 3, }6 U) `$ g2 k& b8 `4 q9 h7 O% ~
  ]
, \1 X4 K: V  N1 I, }, i) k, P+ @/ T2 l/ [3 I  \( c
  ;; initialize the global variables that hold patch agentsets5 ^5 G: Y1 v! v2 V# u
  set roads patches with
/ g, b5 @6 ]9 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, e0 A" ]- P. X, V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 Z! {+ V( z$ ?6 U
  set intersections roads with
. o& F6 ?+ I# ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' K, B1 A8 w. u' o2 _    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 n. F- O" f! R- j- ~( j

9 R! J/ w3 ?& E$ w+ x  ask roads [ set pcolor white ]% R9 [; T2 W' l4 C; z8 U
    setup-intersections
0 D. m. n& ?, K; S7 c4 c8 Wend
5 j( [3 B# M7 M其中定义道路的句子,如下所示,是什么意思啊?& C% e& ^: p8 M& P# o* ?
set roads patches with
" R  K- l& ?8 q0 P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% E9 k4 t/ c3 \. F# K" k- U8 I; `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# s: s9 {* c( S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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