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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。
5 S4 l+ j& n+ c+ x" ynetlogo自带的social science--traffic grid这一例子当中,- r( Z& y8 h+ H9 W7 r+ i. j/ D4 R
globals4 Z7 F/ V) X9 V* O- r# y; W
[
' r& v" I0 M7 I  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. _+ r. D( J* @/ {6 U  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: ?$ q; J# i( Z) q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 R& J& U, @1 F# @                           ;; it is to accelerate or decelerate1 @; m* f. q' I
  phase                    ;; keeps track of the phase
9 N  n) m8 `2 Q; c% e  D- g6 ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. Z9 U7 c9 c& j, F, \; M( s  G  current-light            ;; the currently selected light1 R* T6 A$ n9 L8 c$ I
  _; h. w7 V& ?
  ;; patch agentsets
: R0 ^$ x8 {4 I  A4 Y5 ~! d  intersections ;; agentset containing the patches that are intersections
/ F0 z8 j( }4 C( B4 c: Y  roads         ;; agentset containing the patches that are roads
+ ~! Q( Z/ l0 x+ \" H]
! l; M$ j( ^# U( F7 S3 J
+ l( Z+ M3 M0 W: Dturtles-own
; O* \, n9 O/ U[
! _( }/ u7 l, U! M5 }  speed     ;; the speed of the turtle. E+ `" e, i; @  I+ I3 \
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right/ [- [1 b4 r2 Z: V4 i/ U
  wait-time ;; the amount of time since the last time a turtle has moved
( V' R, [6 m3 {' T]4 b( X- r; |5 F
" Z3 B5 J, q& t% o2 {
patches-own2 s! w) G6 i* G: B! H
[6 Y/ V6 j5 h$ C$ C' J( f  ?# P* O) V
  intersection?   ;; true if the patch is at the intersection of two roads  N" X5 C; p! u) @' E$ v$ R) t
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- g4 n% P' P; w( S" ~" W                  ;; false for a non-intersection patches.
% Q* H$ Y3 X$ E: o; R  my-row          ;; the row of the intersection counting from the upper left corner of the- I1 [0 x) y- i8 `2 {! r+ V$ n" O+ n: u
                  ;; world.  -1 for non-intersection patches.$ W: d* ?' N; b1 Y9 F# t: H
  my-column       ;; the column of the intersection counting from the upper left corner of the$ @! u' Q1 \% y+ U
                  ;; world.  -1 for non-intersection patches.
1 X* Q& d8 R, P' p9 w8 h3 t  f: Y6 g0 c  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* l" Y; A- m% x8 k$ s  auto?           ;; whether or not this intersection will switch automatically.
9 ^0 F# V2 n( {; z8 U! Q                  ;; false for non-intersection patches.( }7 g2 X# ~, e2 t5 f' P
]8 R6 j  ~7 e4 K
4 H9 M# V2 S3 r) O# f) r5 T

5 Q/ f) z# |, ]0 q. g. m/ L;;;;;;;;;;;;;;;;;;;;;;0 S! I$ h" C6 z8 T
;; Setup Procedures ;;
" u3 Q5 a# H$ i& D5 f;;;;;;;;;;;;;;;;;;;;;;
* c& M8 [6 n4 T: X' d3 }7 m7 \) ^  [; W. l# S$ A! E. o$ u2 f
;; Initialize the display by giving the global and patch variables initial values.
5 T8 a3 O: i% n;; Create num-cars of turtles if there are enough road patches for one turtle to
/ h7 C/ y0 j; z2 s+ `5 w3 z;; be created per road patch. Set up the plots.
- s. |9 G% l8 q; @# A$ {' L  U; mto setup. V7 T3 c! ?9 [7 X) p# f0 ?+ ]
  ca( `* ^% i: q8 H8 i. }: K4 i
  setup-globals
8 B2 _" T: f% K+ a% V' y
) `/ Q; |" }$ C4 |( }, C% T- O0 F. w  ;; First we ask the patches to draw themselves and set up a few variables) E6 G3 L8 N# a2 V8 d: v: J3 i  W- Y+ C
  setup-patches4 B( ~; A9 |5 }. P3 t. S! v
  make-current one-of intersections
$ j" }& a( s& A7 U5 e/ t" |  label-current
& O5 s; n: L6 ~( T/ v
0 g, X3 w, I- u" X  set-default-shape turtles "car") j3 v7 I' `0 V
" F. n( y& F5 f% z6 Z
  if (num-cars > count roads)/ B6 h  q0 m1 k
  [
( }6 i; Y6 I  U7 G    user-message (word "There are too many cars for the amount of "& k* I3 B  k8 V9 M, q9 H! P
                       "road.  Either increase the amount of roads "
* B' P' j  t6 u: B" H2 n( M8 S, J                       "by increasing the GRID-SIZE-X or "/ V8 b2 t) H7 _4 j) W
                       "GRID-SIZE-Y sliders, or decrease the "
/ N3 ~3 S# T1 q  K5 r3 W$ Q1 h2 a5 f                       "number of cars by lowering the NUMBER slider.\n". G8 \) }) q$ q7 S0 q) E
                       "The setup has stopped.")- J: Z9 K  M! K/ W; I
    stop
, ]4 Q) K9 |3 n$ G' X, N. |  ]
! O* m* k+ ~# V; Y8 n  P9 I# U( G% M0 `# w
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: y& [8 ]; n0 T  L: _- x0 P  crt num-cars6 O' E3 ^9 X4 X  A: C
  [
' q% v1 O. ^& b    setup-cars2 q7 E# S3 d$ q2 O
    set-car-color
7 d. f+ G$ k* H# ]8 K    record-data
) X4 v# f9 ~6 u+ \- Z" l  ]
% p1 W% X. Z  A1 _. @, K: B% t" }( D& ^# |7 N! U  \2 o
  ;; give the turtles an initial speed
8 |$ M+ t% l: P  y0 o, k  ask turtles [ set-car-speed ]/ M$ v- l6 K  ]4 U9 g

- _: x+ y, d7 e0 G# D- E  reset-ticks' l2 K! \5 I: Q: @& K7 l
end6 n, M+ F: D- J0 m" D

' l, ^3 z+ |- B% O5 o;; Initialize the global variables to appropriate values
. ?2 P! i' x5 [8 X' z0 a7 Xto setup-globals
! ^9 |6 ]2 S! ~% _. a  set current-light nobody ;; just for now, since there are no lights yet
* O' k- [/ s. p  set phase 0
' O9 j6 m) N3 L; Z0 C7 _- O/ j  set num-cars-stopped 0* S, Q1 A4 T. T/ |! ]1 c4 i+ O5 e
  set grid-x-inc world-width / grid-size-x
( P: _& [/ ^& S) M9 T2 p  set grid-y-inc world-height / grid-size-y/ i: E" d$ }/ m- z. d
) y6 U" n' l! y3 x
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
3 G! o9 O5 K* n: B  set acceleration 0.0993 q% k  i8 r$ z- a( ?3 D, ^" y
end1 F+ G, Y' t% i$ |9 w- T
& }6 U1 g' l& [
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: V7 v; V' ?$ \) U! j4 M;; and initialize the traffic lights to one setting
. U% `( l& C& a% bto setup-patches
4 h8 ^7 p- x% t3 C. \4 I: J  ;; initialize the patch-owned variables and color the patches to a base-color! i6 i2 k5 s; G4 e0 Y
  ask patches
7 i* |: }0 B) X: A6 O  [
4 H- Y' B/ |, M; s% K    set intersection? false
" q/ Q* U+ {$ J" U5 D; W    set auto? false
/ }( F4 ?! Y1 q% S' }    set green-light-up? true
7 K' k1 I8 {, F7 a; w/ O( u9 O    set my-row -1% H* ]: J/ q& w. W7 q' u2 @2 E( H
    set my-column -1
9 j: x* B2 I( v) R( r- w2 z    set my-phase -1
$ _" `3 ^( r' z    set pcolor brown + 3) L- ?9 r4 z1 }' z) j
  ]% \) }9 @; T' J: X; s$ }2 f

0 m9 I6 g# o" f1 r6 n- h  ;; initialize the global variables that hold patch agentsets/ N- s9 B! t$ B0 z
  set roads patches with
, `/ C; e1 J0 c  G9 w8 X' Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 T1 i% ~6 g3 {5 M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! }- J+ K# B7 J9 a6 b
  set intersections roads with" s5 }* f7 w) J1 u( u' [# k! x5 D- P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' m( y2 ^; H3 q8 c0 t. E- W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' M  Q& x- o0 c1 P: O
* b) @* e# f) E  p
  ask roads [ set pcolor white ]* m1 [1 ?" {; p+ [
    setup-intersections
* n& T- K5 ]# Rend* J, C- v& w$ L0 o7 {, E# z
其中定义道路的句子,如下所示,是什么意思啊?$ R4 r2 _8 v2 w) e& i4 t' i
set roads patches with/ a. B$ o$ ]7 G+ m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) J1 l3 K+ X: i5 \' W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& r/ {  B( W1 j( j1 v# Z6 W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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