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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 r" ~, M/ o1 {$ Vnetlogo自带的social science--traffic grid这一例子当中,
. F& v1 Q9 Y/ P$ t# w$ K: gglobals
( o; Z4 d$ @: v1 y/ M& _# O" j[
6 b; w: l1 ]3 w# }* x1 E  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 T1 @6 c+ m+ l, W' C+ J  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 }: |! w3 h$ j% C8 S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
5 {4 O: h* i+ U$ |3 k6 A1 C1 j                           ;; it is to accelerate or decelerate
! p) i/ Q: p4 V! k  phase                    ;; keeps track of the phase' k: |- r7 v) K, W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ G. A9 K0 \/ ?7 w' E
  current-light            ;; the currently selected light
2 @1 x9 i  A% x- ~+ Z' E9 ]1 H4 Y* [
  ;; patch agentsets1 j0 e8 V5 v! x2 B3 ^9 l
  intersections ;; agentset containing the patches that are intersections# _1 |3 Y+ B' w: g
  roads         ;; agentset containing the patches that are roads$ g) U6 O: s4 |" S; S1 p4 L
]
6 w% l  D' d5 l! Z# [) {  x) `' w4 s6 w' b  s
turtles-own7 ^, l0 j# M! s& v6 |1 b
[! [7 E* ^1 p8 \2 t* o
  speed     ;; the speed of the turtle: T2 s; j' E. k3 S
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, d9 A; f7 t/ X0 U4 U9 F& y  wait-time ;; the amount of time since the last time a turtle has moved
& U; K3 w5 U& N1 F]
& x8 V8 K) y. G: N  n* k/ W8 n" s( h
patches-own
4 l) J& n5 z/ L+ N( l[3 \# c* ]1 Y! Q5 G/ F
  intersection?   ;; true if the patch is at the intersection of two roads2 L5 z4 C: Q9 h' J0 _, m
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- E4 i- U) F3 w; a$ ^8 Z* b
                  ;; false for a non-intersection patches.
! k# X& Y% ]* y+ C  my-row          ;; the row of the intersection counting from the upper left corner of the
! w% F9 H# J' ^& I, ^6 @7 ]/ n                  ;; world.  -1 for non-intersection patches.; g4 u6 U9 u* e1 R
  my-column       ;; the column of the intersection counting from the upper left corner of the9 K) B4 n% j$ k" o
                  ;; world.  -1 for non-intersection patches." X" O: r/ W& Z( o# F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 h9 b# B" S& o( L2 h3 f
  auto?           ;; whether or not this intersection will switch automatically.
+ Z8 B2 c7 U2 t3 Z                  ;; false for non-intersection patches.+ N1 I7 ^9 n( P- F1 o1 T
]
) f% m" C% [! S& ]8 p( m5 V
5 V% z5 f/ O+ \: _; f. L# g- B# H# k  s7 s6 b4 k7 G8 m% R5 r
;;;;;;;;;;;;;;;;;;;;;;; M7 c; A% K7 y: `1 k" M* h
;; Setup Procedures ;;
$ O# N7 s5 C2 ]- P;;;;;;;;;;;;;;;;;;;;;;
8 y' N0 c7 q+ G" c! f1 w& }. O$ X, k: A! U' v+ O
;; Initialize the display by giving the global and patch variables initial values.
6 p$ T/ \" H9 ?! V' d7 t;; Create num-cars of turtles if there are enough road patches for one turtle to
. o" v; W! F$ r" M% u9 j;; be created per road patch. Set up the plots.
( }& p* f% u' p8 ]+ B0 Lto setup
# C, A* v# b; h  q  V5 e8 F  ca& g% p# d0 g* C* ]% p; ^, \
  setup-globals8 Y2 H( Y8 b  t- s  e

+ m2 y, J- R3 J  ;; First we ask the patches to draw themselves and set up a few variables
9 U& j8 C% H0 s4 J# Q  setup-patches
; ]- E2 A) d3 x9 W7 S6 m  make-current one-of intersections
; z' G1 B* k6 U1 r0 [6 P& P  label-current  N- B' n+ R% [4 J

  V  p8 t( w' Y/ V" }! P* P9 a  set-default-shape turtles "car"
& N) x( ~! p! \2 b6 @' O
4 K  a  a1 I. h- C( `7 l1 k  if (num-cars > count roads)6 M3 f) t* i% l, d4 g: G
  [
$ p1 U3 [6 ~" z; h" v0 [    user-message (word "There are too many cars for the amount of "2 s( I, c0 [) q
                       "road.  Either increase the amount of roads "
0 T. ^% }7 E9 Z                       "by increasing the GRID-SIZE-X or "
9 F9 c( I4 @" \                       "GRID-SIZE-Y sliders, or decrease the ") g' d5 ]3 }; \2 {# l; G
                       "number of cars by lowering the NUMBER slider.\n"
) I$ g! p! D0 {! }" k                       "The setup has stopped.")' s2 _  x$ w4 C) M2 A- n' I; Z
    stop
+ s1 F1 ~$ v& n; b9 d7 N% ]  ]
& |. L$ I) ^, z
. A* c6 j% Z3 t: f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% q& e# J" K, P+ i* f
  crt num-cars
; K* I+ Y8 X7 ^5 b  [: V, U; ]0 `# |3 E8 }8 q
    setup-cars2 z, C1 w$ Z: `6 [  f) a2 j
    set-car-color! T/ e, b0 ^9 ]$ T
    record-data' A: h+ i4 w2 F9 p# \2 J
  ]
) N5 _8 w/ t0 Y* ^) z
3 ]4 V. ^0 d' E1 q0 |2 o8 G1 n9 i' v  ;; give the turtles an initial speed7 S1 `* F' j" P( }# ^' @' ^
  ask turtles [ set-car-speed ]
" L! ?) A- m) u9 k" I
8 t" d9 y& K" w+ U, h( p  reset-ticks& S4 b' D# @2 b* H
end* s0 m8 d9 c) I

  @& i! ?/ L2 Q0 n/ e4 s: U;; Initialize the global variables to appropriate values8 g2 q: H" j' K- v* c+ K% ?" u
to setup-globals3 r% K2 G" C8 m
  set current-light nobody ;; just for now, since there are no lights yet
, m0 l* B. E9 R$ i- L  set phase 0. n  ^7 G4 \' A+ F
  set num-cars-stopped 04 ]6 C' N, S7 R6 a  R9 J3 ~
  set grid-x-inc world-width / grid-size-x
6 a$ v5 E2 j& |- [& C  set grid-y-inc world-height / grid-size-y2 b$ \) Y- x/ {8 P! e

7 |7 m: I* M9 J0 \0 h, K5 W" i  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary( L$ n3 U  [2 |/ Q- `5 x* Y
  set acceleration 0.099# x; f! H, G8 m! O
end: O, P. m+ U: }
$ T% r' v5 A' F* Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
/ N4 ^+ p9 D) q8 g6 l) f' }2 h;; and initialize the traffic lights to one setting
8 v+ Y' }% F/ U1 O3 P8 Oto setup-patches9 c' `! \  U0 g5 P, ^, ?1 V
  ;; initialize the patch-owned variables and color the patches to a base-color! _2 f+ {7 o# a* j1 y! ]; ?
  ask patches1 k, r) G" r) n6 ~/ t9 S  i, w
  [
& g- e/ U0 C+ r3 n+ n6 D/ U    set intersection? false
. B4 D0 ~- O% r! X    set auto? false' W! V6 e: k7 }3 U, x- j
    set green-light-up? true; a0 w9 h' _  ?. U
    set my-row -1
" T% N0 u4 r8 @6 H- j' v4 P/ r    set my-column -1
9 X' w, O; c# Q    set my-phase -1
; `4 N* P( C! u6 V8 B7 j    set pcolor brown + 3" `: r# v$ p. ?1 a
  ]& c/ w  X  n5 v+ B
+ P# }9 B9 f1 w4 W9 K
  ;; initialize the global variables that hold patch agentsets
" r/ [3 E0 [9 W5 v1 A  set roads patches with
* U5 ], K# O1 ?3 w5 X! _! O/ ~    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ K+ K) C* U% J5 F: B6 @# f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 F0 \3 ]' @8 v* T
  set intersections roads with' k& }: e2 w& c& G6 x- h$ S( E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 t5 {, ]3 F3 ?; q# ~- _: c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. d7 D- F: R. r3 `6 j$ n# r2 E1 E* d
  ask roads [ set pcolor white ]) X  n& [- a/ K, x+ w8 _
    setup-intersections; J; }' H, y* V# }" d+ ?" T$ D
end  {( |* `1 Q3 c
其中定义道路的句子,如下所示,是什么意思啊?
& B. L. ^  R) z: D9 G/ x+ ^ set roads patches with$ }( E' p3 f% u- J5 Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 w. _; x) S* S! b: l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 u8 n& e" n" E3 L- {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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