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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。
) b1 n, w4 T% x5 c, v$ W$ ^( knetlogo自带的social science--traffic grid这一例子当中,
0 ^. p) ^! o  }9 l/ xglobals; R, t/ Y7 A* w( q3 b% R
[
$ `$ Y6 }: b! k2 |9 O' Y  grid-x-inc               ;; the amount of patches in between two roads in the x direction) |! }/ W0 p0 c  q2 V$ M
  grid-y-inc               ;; the amount of patches in between two roads in the y direction4 N, A) t7 j& s; J+ o
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ R; e: ~5 b. L                           ;; it is to accelerate or decelerate
  o- o' x7 u9 ]5 C* h9 Z  phase                    ;; keeps track of the phase) p- F- z6 X( v/ U
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' l4 Z7 O# X9 g; Q! t! j  current-light            ;; the currently selected light
- C- D! F5 w- q  J8 P
, `; w! i0 R; P  ;; patch agentsets3 g% V$ |2 \1 y! O8 R  p) `
  intersections ;; agentset containing the patches that are intersections, a8 O6 M& L9 r& l
  roads         ;; agentset containing the patches that are roads
6 K: E+ t% {+ Y5 l4 M- []! C8 C! Y" @9 w' J" a4 U
# s9 C% _" e& S8 u( F
turtles-own& h! x3 a) o, a2 U. D4 w$ y0 G
[  R: X# \3 V" i6 c! Y
  speed     ;; the speed of the turtle, X: S; Y3 y* A- D. f6 J- x& m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 ~1 t* n- s: g7 I% Y% X4 Q' G( g  wait-time ;; the amount of time since the last time a turtle has moved" A, X# F# I8 e5 N# O* z8 \$ X8 f
]7 {- t7 U" J! F- Q) ?
* |- B; \0 h: _3 }
patches-own1 Z( k$ w# K7 p6 m" e
[6 ?2 {7 g) ]. a/ u* o4 Z# n
  intersection?   ;; true if the patch is at the intersection of two roads& l2 ^$ d5 M( W
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  R6 z4 h( [  g0 S                  ;; false for a non-intersection patches.
: W7 |; K' Y2 h! F% |  my-row          ;; the row of the intersection counting from the upper left corner of the
0 _5 K+ o0 A; x- N1 H) _                  ;; world.  -1 for non-intersection patches.
2 Z8 T: B1 I6 P' {6 V/ o8 T0 u# C: B  my-column       ;; the column of the intersection counting from the upper left corner of the% V% T) m- h4 d$ ?$ |% k1 ?+ I3 a
                  ;; world.  -1 for non-intersection patches.
! B  b8 s/ x! [* v% ^0 c  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! z* L0 E2 Z) ]  R  auto?           ;; whether or not this intersection will switch automatically.' y1 c$ E/ Z3 ^: t8 V; `3 u
                  ;; false for non-intersection patches.+ s7 |7 `  Y+ ^  o) z+ o  C4 ^
]) d3 C. `' v/ W1 E( l3 G7 d

% w: l0 Y& q7 |' Q. h8 }
# f! U. |, c3 U  l4 ^;;;;;;;;;;;;;;;;;;;;;;6 J; v. B6 n' P- d
;; Setup Procedures ;;
4 e0 k- E* T9 I;;;;;;;;;;;;;;;;;;;;;;6 S- k4 `. |1 A0 f. T4 p
5 B7 a+ ~4 S0 _& E: I% u. I
;; Initialize the display by giving the global and patch variables initial values.8 O0 Z) M) F6 a( Q6 v# Y5 W$ o
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 _. K9 ]+ Q. F0 F2 P;; be created per road patch. Set up the plots.
* _4 R4 L- m7 p5 O! ~to setup7 Z8 t9 Q% v& |# [( k/ t9 [
  ca
# S, k" _# U7 ?5 M: e/ j  setup-globals
2 D( G% ]1 a* y& g. e( ]$ E0 I1 O
  ;; First we ask the patches to draw themselves and set up a few variables
/ h" e# o( g; P0 m9 d  setup-patches6 [5 O& b: e- C! Y/ I+ H/ @
  make-current one-of intersections
6 R# ]  Q. n- ?: c& ~" W  label-current
6 w3 H' K; ]. _4 O
/ m% P% S. x3 T  _7 a5 \  set-default-shape turtles "car"
7 I$ `1 _- L3 `8 X, a. @* v! ]/ }
* r2 a' ^) S7 f! I" L# x  if (num-cars > count roads)3 |5 l- Y% ^& J# ]
  [
& L2 o! F9 v+ a3 J! x4 e4 T( g    user-message (word "There are too many cars for the amount of "3 l. U0 J8 d. S
                       "road.  Either increase the amount of roads "
% t; t7 R/ I2 ], e  \                       "by increasing the GRID-SIZE-X or "/ e6 D- @  J4 X6 b9 V7 Y  k$ b
                       "GRID-SIZE-Y sliders, or decrease the ": e+ Y" `& O. K9 G& O
                       "number of cars by lowering the NUMBER slider.\n". u( _) T8 C3 D% J
                       "The setup has stopped.")
: a: E# b4 D' k/ N5 n& A    stop4 f0 f7 |8 Z' b
  ]$ T# P( e; L* e+ |; R  q% V6 E/ v

! i0 k  W) A$ G$ A: U0 M' D  g" g8 t  F0 x4 j  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 Q9 `. b/ J) b3 v/ ~' J/ v
  crt num-cars
( ~/ l% x+ Q4 O3 l  [' [! `  P9 `: _& {/ }) E
    setup-cars, U( b; x) z6 ]. k4 s' _1 x3 M
    set-car-color5 O9 }4 y# t' c  ~
    record-data
7 c, O" I  `7 w  ]
- ?" Z, i  `, C5 m" x8 |% W' y* M9 ], Q+ `) Z, l; N8 ]- o0 s
  ;; give the turtles an initial speed
0 D6 a( M' s! x# v! u3 O2 u  ask turtles [ set-car-speed ]9 L/ ]  T6 c" l5 u# ^+ e* _
) p% j( r! Z- ~. Q, m+ \" S  A
  reset-ticks8 |) X. \8 |! v6 h$ `3 o
end& N, t2 F3 `. z$ y4 c  e
) X* A$ K1 ~0 J2 K, J* y; C2 C
;; Initialize the global variables to appropriate values/ k2 U3 i# N3 ~: n3 `2 g/ n* `
to setup-globals
  G1 J/ f; v$ |$ i" `2 X" v  set current-light nobody ;; just for now, since there are no lights yet. B- [; L- T/ f. w
  set phase 0
8 r* M& b3 T8 u9 g7 I  set num-cars-stopped 0" U3 V2 N: n% l' S0 J$ Z5 b
  set grid-x-inc world-width / grid-size-x
& I( R7 u( a" i- A& |  set grid-y-inc world-height / grid-size-y0 ]* ]1 F$ k) D

5 T- d6 W; S7 X5 q2 X/ h  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary6 ?* q2 k& w4 R
  set acceleration 0.099" P& N0 L) @* e) I1 E9 i
end
8 v9 w3 D1 T9 N3 x/ I+ U: u5 n8 v# |5 ]5 a, D
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. T/ ?! C/ H# x/ C. P( d. ]
;; and initialize the traffic lights to one setting9 H$ K4 t  q9 k" \/ U. U# G) J
to setup-patches
7 H6 R2 `$ O4 {/ K  ;; initialize the patch-owned variables and color the patches to a base-color
% O. }0 G' ^* @& w$ s4 i4 U  ask patches
/ Z8 X- y% V( `7 A" t6 F- i5 ~  [
1 _7 h6 Z$ s2 ^- j    set intersection? false$ _/ w  Y3 S' ]6 W
    set auto? false
9 l" o5 F  {( c! n    set green-light-up? true
' m/ \" Y& |0 P: v2 j    set my-row -1
) b  Y/ u: Y3 X2 k. r& j0 Y7 ]" r9 ]    set my-column -1' N# o& ]; i1 Y/ k1 S, B2 i2 A$ y
    set my-phase -1
# L; X- L0 p0 l' t" @" h    set pcolor brown + 3/ z2 j, P7 k5 [; V6 q
  ]
+ |  J# @1 ?; b) b- i0 k" M! x6 G8 Q4 _+ o1 o0 `( d! a; O7 Q
  ;; initialize the global variables that hold patch agentsets( z7 ?6 J. ^$ a7 D
  set roads patches with
! b) t/ ^/ ]' L# ?2 [7 \+ c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 j4 ~. C" A* X  \% M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) Y7 {5 k2 u: z0 F7 J
  set intersections roads with
& `( y7 R8 t7 m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 D* h2 i" [$ u, `* x% W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ j' i* k- L- Y* z/ {' r
# f5 e4 b! n% I  ask roads [ set pcolor white ]" {  v" G( G5 _$ T5 Y
    setup-intersections
7 Q1 l8 f) ^; _* a, x0 x7 |end
4 z6 O/ L3 Z' `% x+ W8 U- l其中定义道路的句子,如下所示,是什么意思啊?
5 o, M& r% P% o* j" E1 { set roads patches with: j2 U( \! J' K( r5 ~- G( @" Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! I3 \# ~5 b# g! ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) I' W, J) L& h9 o  d' \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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