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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。
" g8 z) ]3 d" W9 z6 Y. n7 q6 K% x, Cnetlogo自带的social science--traffic grid这一例子当中,; ^6 l/ F+ L0 f- Z( ^
globals
, @7 g$ Z4 f) z& Q[
4 J" D7 s! e5 q7 u  grid-x-inc               ;; the amount of patches in between two roads in the x direction
: G# V" ?8 P7 z4 ~  grid-y-inc               ;; the amount of patches in between two roads in the y direction, X3 {6 U" V3 F  [
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( I* g1 K! h# w                           ;; it is to accelerate or decelerate1 r" S: S) F' ~: y% m
  phase                    ;; keeps track of the phase
3 O1 G9 Q" X$ b; f/ E/ w  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 t" m; v! m; o! p; \& v) Q  current-light            ;; the currently selected light
3 c0 v+ ~( A- r- }8 }9 r" P7 [! D
  g. E# H2 X3 E+ O1 m) C; |  [  ;; patch agentsets
' @* A0 ?3 j% d0 o- [) }! t; D  intersections ;; agentset containing the patches that are intersections/ W% `/ E$ h9 q) T1 i# Z5 g5 k
  roads         ;; agentset containing the patches that are roads* u% F, b4 K9 D( ^9 }( l% @( }
]
. c+ H; E+ u$ w# l6 L- k) a# P4 Q9 x3 Y5 L  u
turtles-own
$ P  a3 _0 I$ G[
. z& a4 A; p1 W2 A0 n; e  speed     ;; the speed of the turtle
/ O7 n# g% T0 l6 F) @' Q1 q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 N. W( P: e4 L4 b1 [  wait-time ;; the amount of time since the last time a turtle has moved
- y8 s. @5 H$ g' g" S! m! m]) e, l' w- ?" o' J0 z
% p+ `4 \7 O0 P& i+ i; G
patches-own! A8 z4 M6 Q7 W; h% D: M7 O
[+ i/ }0 M4 `' ?0 C' n# H( q
  intersection?   ;; true if the patch is at the intersection of two roads7 k7 a' t& d9 z, u9 d7 @
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! k! H$ ]' O: Y3 O4 k                  ;; false for a non-intersection patches." C) L4 \9 F2 R& F& {0 H
  my-row          ;; the row of the intersection counting from the upper left corner of the8 \/ H4 I' q: }
                  ;; world.  -1 for non-intersection patches.0 x$ T# M5 `7 C3 ]
  my-column       ;; the column of the intersection counting from the upper left corner of the
' r: z9 g& Q- q+ y1 t6 L/ D# `3 Z                  ;; world.  -1 for non-intersection patches.
: d( _% A7 G$ b& T3 v  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.; m5 [: @% G% @4 o1 w9 O0 d" |
  auto?           ;; whether or not this intersection will switch automatically.
5 L5 i2 g6 Q' T' l, t# C1 g/ ]1 Z                  ;; false for non-intersection patches.
3 i$ V7 q& P1 f$ r8 s3 \$ h$ _5 \]8 a+ B' r/ v" q& K, Y

2 @# I5 V/ E1 d+ g& U) X4 l* d% B7 z' D4 E# n+ i) O
;;;;;;;;;;;;;;;;;;;;;;' p% E4 f$ n" D+ V# Z0 i
;; Setup Procedures ;;- ^9 B0 q1 d% p; s7 h2 j
;;;;;;;;;;;;;;;;;;;;;;# i( u! u$ ]) E3 h; ?
" F% w* j9 N$ p- s! J  [
;; Initialize the display by giving the global and patch variables initial values.0 G& Z, Y0 p# P4 T! J2 i' _
;; Create num-cars of turtles if there are enough road patches for one turtle to
  F' M7 v. V% W$ T$ g3 r" j4 g1 L* P;; be created per road patch. Set up the plots.- J0 R" b4 r# @6 t, W+ S
to setup' l' J$ X, h& d4 H4 x
  ca5 J4 |. Q2 C. K! @' O
  setup-globals8 g+ N% h2 l( ^1 t- J
( Q+ f4 l8 R- n& [3 w' a: W
  ;; First we ask the patches to draw themselves and set up a few variables
1 D. N9 w' x/ h; e3 ?  setup-patches3 e& Y8 s2 u" c  K
  make-current one-of intersections1 b$ t; {: j6 S& Z0 D# _
  label-current' H' U* Z9 z7 X
  u) m- `! m) v8 c. F2 b' C
  set-default-shape turtles "car"
# ]& ?+ L2 h' j4 {% B7 }, s
1 Q) \* V: [1 O6 `9 R: _  if (num-cars > count roads)
' z  c& {7 h* Q- |6 v  [
& R5 D1 {8 Q; W, r4 K, y    user-message (word "There are too many cars for the amount of "
* D! d0 ~# W% G                       "road.  Either increase the amount of roads "! c0 W' k% E3 _# n* g% B
                       "by increasing the GRID-SIZE-X or "
) M- ]$ N) y4 L! K$ Z4 O5 X                       "GRID-SIZE-Y sliders, or decrease the "; }) e2 a3 u9 ?6 g$ m! S2 U
                       "number of cars by lowering the NUMBER slider.\n"
' O  l5 K+ W2 D; l                       "The setup has stopped.")
% P) {# |" D& v' }3 ~. T" K% R0 U; j& @    stop
! O2 o( }" M) k1 w) S  ]
7 A. R$ ^, W7 u$ `2 [# T2 V- E
! p7 t9 W. x) p+ f* o9 E  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 t% M3 G% [+ Z5 C
  crt num-cars
, T3 E  J% n/ K1 Q! h  [
* q; C2 P5 F; Q+ ^6 W7 Z    setup-cars
& D$ O5 T: F, ]5 q# ?    set-car-color/ b" C4 C" E: v7 O1 `6 G3 V! [' j" q
    record-data
! G, v% @) p1 x7 g7 }  ]) Z$ p; _% z7 o4 d1 W6 Q" y$ `

% \; ^% d8 z5 M* y- n  ;; give the turtles an initial speed
1 j+ J$ e$ P2 {' n* Z" L; x. T2 ~  ask turtles [ set-car-speed ]
3 [! D! f* i$ }, X: R# u, Y- z7 T4 U' |% D0 R
  reset-ticks
. U5 O" d; ?) Vend2 y3 T6 N( m3 y) s7 O6 f' j+ N6 [

4 U# M! j, F! L1 [;; Initialize the global variables to appropriate values) T( C( E! b! s8 `0 i  F
to setup-globals
5 t3 N0 B2 z5 b) |, q  set current-light nobody ;; just for now, since there are no lights yet
, W6 c  D# X( R+ t$ G6 O+ @  set phase 0
" v6 q5 L- C" Z/ y  set num-cars-stopped 00 \7 I. E4 N6 X! G, L
  set grid-x-inc world-width / grid-size-x$ H0 J# P/ j; r# V
  set grid-y-inc world-height / grid-size-y! B9 s5 e# `$ o& ~+ u
" s" J0 K# S( S- Q) e- F
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ j3 ?5 V( E" c& {9 @/ F  set acceleration 0.099) k2 w$ E" z0 k) F- G9 z" D5 E
end
/ W$ `) C, B6 Z( p, c" M) e: {. G4 ?0 X2 w* |) B. t" I
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ N& V  Z* ]  x  L" O; Z;; and initialize the traffic lights to one setting3 B. D5 ?1 V& @: }5 H2 }, J
to setup-patches& X/ L; e  U( `: z2 P6 B1 E/ J5 O" ]
  ;; initialize the patch-owned variables and color the patches to a base-color' p2 g4 M' N/ R# c8 y
  ask patches! b, M" ^* ?9 I. @- [. A4 t
  [( D# D( H' ~2 a. J
    set intersection? false+ E7 s+ \# o6 {7 a% @( P0 t
    set auto? false
" u- _/ m! Z4 D" u, \    set green-light-up? true
! t5 C9 ~. b, B. q    set my-row -1
( ]5 K; z& p: y4 a! y7 O$ ]    set my-column -1* N* P. u6 G9 J" i
    set my-phase -1+ e9 @: R9 O' B. m0 c) X4 D) ]" U
    set pcolor brown + 3
* u8 \6 q+ g6 S# Q  ]
: g3 g. F: q" m3 N2 d  q( d/ ]4 R( S- v
7 E8 _! h9 ]% w! z- J% L. v  ;; initialize the global variables that hold patch agentsets
8 v( k0 @3 |& i  ^/ b  set roads patches with
; D7 W& ~$ O, D# y. G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 ]; \. D0 ~- ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 r# d, F% P" C9 q& o* ]  set intersections roads with
4 }  y. d3 d; Q' l5 h- I6 ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% F: H1 D2 T; C9 e1 ?) u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  L, F# N" G5 O; j9 V  R7 [2 t

4 n1 B) k- b. Y6 K6 o  ask roads [ set pcolor white ]
: c) \3 d0 T3 o+ l- z; H9 s    setup-intersections' V8 q) d/ Z+ b. L7 ?
end' v% X8 ?: L, Z* f: [5 d
其中定义道路的句子,如下所示,是什么意思啊?( }6 [* Q1 r( N: I
set roads patches with7 W: M& |; S' f: `
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ O! h8 O, n# M4 X, ^  |" b7 z, R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: K- I7 \' f" e6 d" e) d. v" K4 |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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