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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。* u, y2 ]0 J* w* f" S
netlogo自带的social science--traffic grid这一例子当中,
0 m7 K# a. G# Nglobals
4 @7 ^" ]) T- a+ m[
: k' E7 L6 p" j! @) O  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  z( D4 M& {8 d1 r  I% d/ j% _  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 W& s3 o' q) d, b6 x* ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
$ R) O) m+ Z9 R                           ;; it is to accelerate or decelerate- A! i  b! U) u
  phase                    ;; keeps track of the phase
6 j5 K5 k5 n# k5 y3 X6 q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' M4 T  o% q+ x0 x6 U
  current-light            ;; the currently selected light
. |6 W& }- {/ }5 g
, J, c" q. j+ |  ;; patch agentsets2 D- q( j! P9 x  ~# h
  intersections ;; agentset containing the patches that are intersections; c1 Q# A3 ^1 o) W! N4 I
  roads         ;; agentset containing the patches that are roads
- X9 I. v! M" _; I& C+ G$ q2 h]
% X( {3 v  {  G: k2 g: A" A" z: S' B
turtles-own
( u0 i  _5 E' U* T- h[
& c$ T: u6 f* L, E  speed     ;; the speed of the turtle
# m0 I: t, ]2 ~$ K# `7 h: f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) A/ H- k$ X, Y  wait-time ;; the amount of time since the last time a turtle has moved) m" h; A- K  o( R
], C7 e  U6 E& r* d4 c2 E( b& G4 a

/ y$ K: n2 z2 U( u: I# e! r+ ^patches-own' m; {! l. s* f; J$ b6 J  ^! X
[" S5 c9 M( ]* e/ \9 U6 S; p
  intersection?   ;; true if the patch is at the intersection of two roads: z  X9 Y& r/ I, z- U9 [3 V9 O1 D) }
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
0 O3 r& h* R9 T6 }, I% P! j4 S                  ;; false for a non-intersection patches.( A5 }$ D/ n) W7 {8 g
  my-row          ;; the row of the intersection counting from the upper left corner of the9 c3 e. ?, D# d8 _$ k4 b& n
                  ;; world.  -1 for non-intersection patches.
' W/ r- r' h; c! R8 j6 _* y  my-column       ;; the column of the intersection counting from the upper left corner of the
6 [# n- `) C( a; K7 g                  ;; world.  -1 for non-intersection patches.3 |  ^, S- k( e9 s( v
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ P' u/ O. Q( ^# F/ R
  auto?           ;; whether or not this intersection will switch automatically.
% u* N8 X/ E6 T, |, n9 \3 T1 H                  ;; false for non-intersection patches.
: W" A4 X0 B/ M# _# _; `]
/ ]- w# `6 z6 `8 G, a2 ^6 b! I4 u8 _& f1 R! W

  \2 t+ B5 n" v( H;;;;;;;;;;;;;;;;;;;;;;* {: x, Y  M* ^
;; Setup Procedures ;;
' D' A/ m/ R8 @; I) l' \& c/ A;;;;;;;;;;;;;;;;;;;;;;, u# ]( j) q! m% H4 `0 p; q
5 H1 k5 @6 a+ [- @. l  F" j
;; Initialize the display by giving the global and patch variables initial values.
8 |- K6 _! y/ g& D5 a7 q: v;; Create num-cars of turtles if there are enough road patches for one turtle to
" Z6 f' J" C8 n: ^# l;; be created per road patch. Set up the plots.. z* M8 n- E" T: c% {
to setup7 R* b/ ]7 I" k& H* p8 l
  ca% b9 ^) T( r5 p1 N, q: o7 t4 k
  setup-globals4 S1 J& _% Z- Y3 {  d) P4 b
- d0 U* f+ r9 J
  ;; First we ask the patches to draw themselves and set up a few variables
; Z# v! }" H3 ^, n- }& J. P4 t  setup-patches
' Q, l. b' k# K3 i: t5 G  make-current one-of intersections2 G' t8 R4 p0 A, S! ~3 O
  label-current
9 W7 ~& i3 o, p6 O, h3 ~' p0 g# }: U# W  V
  set-default-shape turtles "car"
, U& K: g4 ]: S( f- Y; P* h$ k; M: ?: w/ B
  if (num-cars > count roads)- A$ }" F2 {7 k3 V! c
  [
( K9 {9 l( G+ g    user-message (word "There are too many cars for the amount of "5 f" v$ T' m  o" b  Y4 Z3 y
                       "road.  Either increase the amount of roads "
4 V1 J# i" \- U& k, z8 L                       "by increasing the GRID-SIZE-X or "# E" w3 U) O+ m0 r9 J3 m1 g
                       "GRID-SIZE-Y sliders, or decrease the "+ {  g8 n! Q8 h) l2 v6 I( I2 N
                       "number of cars by lowering the NUMBER slider.\n"
/ w  f: C: _9 a, u; O8 Q                       "The setup has stopped.")5 j' N5 q- W2 U2 @3 ~
    stop( ~& X! L3 Q1 D+ m2 S& z- D; \' F
  ]
9 Q$ B' `# x& X* N' p7 ?$ ?* `
$ ]& S" P  \8 m8 h. p# s, s6 F" @  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& A5 H5 @7 M; R6 p" i! r+ _
  crt num-cars
- ~& N9 a! s# C/ t. ]  [
* I( M7 P" I4 X- W    setup-cars
4 f- e7 D& g1 v% X5 N    set-car-color: @$ `; ~- ^# b) S  ]% N* g$ N
    record-data
/ D- u3 ~% J: c% H7 H+ o  V  ]
9 q! a5 E$ j5 P6 t  f9 i% u9 ?; R9 D5 |: _2 y4 ]
  ;; give the turtles an initial speed" m5 t/ [7 C7 b2 I0 h% o
  ask turtles [ set-car-speed ]# ~  q6 u& A* f3 U2 ]

( s5 K4 t5 f) u' R- O  reset-ticks" S5 i. y0 @+ j/ f) P! g
end- \+ m% A6 u7 h3 R
# \7 u+ V/ {7 `; N
;; Initialize the global variables to appropriate values/ Z" B8 X) {" t1 f" G7 t- M
to setup-globals
& F; c+ K( [+ m& h  set current-light nobody ;; just for now, since there are no lights yet$ A  A6 B" X* E1 t* X# w
  set phase 0
! ^8 t& J* {% x- {9 p% A2 v  set num-cars-stopped 0* `' s* L+ Q6 `1 E9 `9 N% t
  set grid-x-inc world-width / grid-size-x
6 E5 ~1 }+ I& @  j7 c: B' @; o  set grid-y-inc world-height / grid-size-y
. T$ q$ O9 o9 y
& e, r7 X! D# q3 \% Z0 B0 T  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- S; C3 l. h5 n7 e, {  O' y  set acceleration 0.099: V5 M% `" n( y0 C) }3 }
end- Y7 s& J: \! Y% e6 i
) ^) T# r% F( R+ b
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,6 \7 C$ ?8 w# R, r7 q
;; and initialize the traffic lights to one setting
5 X  J& O2 b' @  w( `to setup-patches" u! y# P! M8 s4 ^( o
  ;; initialize the patch-owned variables and color the patches to a base-color
" f+ K$ Y0 \. G& B" n0 V$ d% e( p" s  ask patches. M( T2 b7 ]1 j  O  v
  [2 w6 h; ]' U/ u/ X8 N
    set intersection? false
4 y" \* V% \/ j6 g    set auto? false
% F! c! m' \% {    set green-light-up? true
6 M/ h. B1 o% ^. y5 h    set my-row -1
. @; m& j& o- E8 I2 @0 [    set my-column -19 V) U  T. z6 \: @9 j; g
    set my-phase -1' A$ Q4 B$ ]- t3 \; ~$ J) B
    set pcolor brown + 3
5 Z3 }. r5 a9 @5 S: p0 Y  ]+ ?2 V. F: ^+ {! S
: _3 z  s' B" ~% ~. I) s. h
  ;; initialize the global variables that hold patch agentsets
' p4 R4 {( F* m+ K% l! i6 Y) d  set roads patches with
! \0 I7 ]; M& ^) u" V+ }+ U6 ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& M4 E! P: }  K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 \* ~2 t$ o& T( |
  set intersections roads with9 A9 R. |1 \- r2 R: ?( J7 V- {9 i5 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ d6 ]6 k( t4 M6 J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 O+ g2 v) y* S$ a, o
% t& M- T9 I4 l; i/ A
  ask roads [ set pcolor white ]* Y+ Y: C7 W4 r; c/ Q
    setup-intersections& i& G) u4 ]7 @, ~3 N: d, u( o
end: e  q2 _- p  t3 L4 ~/ r  U, Y
其中定义道路的句子,如下所示,是什么意思啊?# B3 {" P& `4 I; O
set roads patches with4 f! @2 o8 v0 p) p/ o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, G5 c) t  W4 w0 L. D: a7 ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 G" r: V- G! ?$ Z9 Y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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