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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。
1 Y6 G' I+ g: _9 Q$ hnetlogo自带的social science--traffic grid这一例子当中,
3 x4 v- ]7 j4 T3 u) V4 B& `. Q7 M  C3 Jglobals( k" X. d9 C" f3 i; n2 }
[$ M" S7 S$ w% s0 M
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 m# }! Q1 `* @9 l5 T3 ~
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 `! v3 j0 b0 l. B
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' @( l0 Y/ O, s/ l. f) ?. n  o- |                           ;; it is to accelerate or decelerate) G6 c# \6 o& i, j3 S7 z  X
  phase                    ;; keeps track of the phase+ n. x  g5 Z2 y7 ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: @$ O; K6 ?2 c+ ?  H2 o
  current-light            ;; the currently selected light
3 x% H! o' d4 @. p3 ^/ j" H2 S* N& D1 P; N# s4 i) U6 r
  ;; patch agentsets7 k: A( v& R# s* V
  intersections ;; agentset containing the patches that are intersections3 p, m5 Y' ]1 i/ B
  roads         ;; agentset containing the patches that are roads, l! f0 O  ~. c# g
]% K6 b! S1 W( W/ `7 S% s% M

  S3 K& V& _: r/ F! gturtles-own
8 ?9 o' K0 F' `[
, i: K, @6 V* _  speed     ;; the speed of the turtle
9 V' S7 W: J0 h4 |' P% _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# w8 k" h6 O% f7 X7 c3 \  wait-time ;; the amount of time since the last time a turtle has moved
3 ?- _% S: e5 X0 ~  m]8 v8 \6 C6 F+ s$ s) @: [* R, Y2 q

6 I1 F* e$ |% U' M$ _  H% M1 M7 \7 kpatches-own
# ~' m9 P" f, ^. ^/ w/ M" H" B[# r; I8 m9 N6 ~, M& }; o
  intersection?   ;; true if the patch is at the intersection of two roads5 j  [8 ^) @( J% [
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- b2 r$ W( s( d+ b                  ;; false for a non-intersection patches.9 [) l( n' x# n+ G9 z8 q$ F" W
  my-row          ;; the row of the intersection counting from the upper left corner of the5 ]) h" ]2 r  E$ d
                  ;; world.  -1 for non-intersection patches.
/ I( }& D! ^) e. c3 S  my-column       ;; the column of the intersection counting from the upper left corner of the
& a9 o/ c& j% f                  ;; world.  -1 for non-intersection patches.
: Q) y% l4 V1 b9 n6 i/ i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 F1 u% w$ w% W! J$ X3 @
  auto?           ;; whether or not this intersection will switch automatically.
% ], L; H8 `* T  O                  ;; false for non-intersection patches.
2 D* h* E  Y9 I, p9 P]! P, r6 S, u4 Z4 K2 |2 O+ _

( z8 X; z- C2 r2 E/ r! ?7 t6 J' }& J" h1 |; X
;;;;;;;;;;;;;;;;;;;;;;9 V# e1 q) X( e1 E/ F8 Z/ g
;; Setup Procedures ;;
1 m6 O4 e+ l3 m. N% f6 H2 |, X) }6 m;;;;;;;;;;;;;;;;;;;;;;7 q6 H/ h7 ?! r* i8 H( n: i# S
' ?+ F$ |3 Z: r+ _/ v" I
;; Initialize the display by giving the global and patch variables initial values.$ B( _3 b/ O" c+ A* Q8 j7 m
;; Create num-cars of turtles if there are enough road patches for one turtle to2 Y' R6 z7 A, }' [% y) {
;; be created per road patch. Set up the plots.
5 U+ `2 Q4 Q1 [# cto setup
; _0 j9 L. l$ c- m  ca- J' `! @  D8 A4 U' z1 S& ]+ B
  setup-globals( e* x) |5 m6 b' T* R
7 w4 D) _! o& B- f
  ;; First we ask the patches to draw themselves and set up a few variables8 H% E! l- B$ V& ?' @, q
  setup-patches/ L) o& \- r: a4 l8 J8 H- _
  make-current one-of intersections. q$ a1 O! {' I
  label-current1 P+ r; e5 a) K* z+ M2 f
& c  l; N- c% e' ?6 f8 m
  set-default-shape turtles "car"4 {) q3 s! S* I" }$ ]" \  |! o
( w& o% [. X% ^% z3 m% A3 t7 K
  if (num-cars > count roads)
9 q. d7 r5 J- g* T4 r  [5 g- R2 P5 O1 o8 z  s
    user-message (word "There are too many cars for the amount of ": y9 @' M9 k7 l& m8 I
                       "road.  Either increase the amount of roads "( y/ W& E3 A" ^  A8 P" n# A
                       "by increasing the GRID-SIZE-X or "" x" L% |9 p8 }$ L3 c; i
                       "GRID-SIZE-Y sliders, or decrease the "+ A! A: g8 A2 q# a3 w/ H
                       "number of cars by lowering the NUMBER slider.\n"
7 z4 a% l- o& G1 f8 I7 y                       "The setup has stopped.")7 V6 A. R1 [2 v
    stop
; ]/ U5 j0 j/ ~6 N; c4 _  ]' Y  H) L. t% ]1 F# _: T0 U

' g; E0 C/ E. n$ Q' q0 e  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% c5 G$ j* @5 c! {% ~8 J0 m0 A+ j& N
  crt num-cars
; h  ]7 p2 D8 U  [
3 W. m0 m# p( {2 U; n/ S! o% z    setup-cars
1 I3 H7 l2 w6 X, r  A8 G    set-car-color
3 @: a$ I: i. K9 R$ ?    record-data! U5 _+ s: R; E6 T6 f; j
  ]
* Q3 Q: z. N$ h  e4 K% |- j6 m
- I% ^, y$ u, Y5 f& a  ;; give the turtles an initial speed
# n  s/ Q, Y3 J  ask turtles [ set-car-speed ]1 y: V) W4 E3 {6 {/ U) x
! C; t$ h7 g8 ~
  reset-ticks* V0 V3 x' ~& z
end- L( p; }  j  U2 `" F# X
! k  C- m% Z, H7 n# h  p7 m$ W; V
;; Initialize the global variables to appropriate values, x% \4 F+ V3 W' f5 m
to setup-globals/ q5 U9 M/ H( [2 K8 P+ ]% c
  set current-light nobody ;; just for now, since there are no lights yet) R4 {9 o! b  e! C
  set phase 0+ J$ s7 F$ V/ P$ v% ?# V
  set num-cars-stopped 0( t% x$ C5 q5 P6 z7 _. O( P' T
  set grid-x-inc world-width / grid-size-x+ q" X1 m- k# L/ k  n7 Q
  set grid-y-inc world-height / grid-size-y
4 I$ a0 U1 N( o. P  n
7 R, Y7 u( ^- F& U- x/ x' v  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
2 Z) C" v* K1 C, R  _' ^& T: s  set acceleration 0.099
& N) ^$ ~; u% {* `' G, |) g, pend* a- p6 r/ A* f' H+ N& s4 I- ?

; U: `2 F" f$ A2 U: u" L;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 i9 E+ u6 T) w;; and initialize the traffic lights to one setting
" t1 M8 w; Q4 h) dto setup-patches+ j' N' ?' X9 O3 z$ `  K
  ;; initialize the patch-owned variables and color the patches to a base-color2 M2 R0 m( {) z; Q6 a/ |8 @" j6 r
  ask patches- i; Q& Q4 B9 K% M% b2 ^3 J
  [
/ a' }+ a5 c5 k/ i8 e    set intersection? false
+ Z9 X& }& p$ U3 e+ |% ]" ]    set auto? false
$ {8 U, o6 u! |( n% o: H% W& l    set green-light-up? true
+ M+ B3 J2 y8 J, K9 D    set my-row -1  n4 Z2 N% X* V' g2 H
    set my-column -1
* u1 P% a" f9 I    set my-phase -1, R4 o6 ~/ D+ x2 K4 {
    set pcolor brown + 35 y- f: I$ ]9 o  u
  ]
/ h: X# H4 I  I  @0 {# M3 H" c% z- H# {" s' M: o* E9 {# f" N
  ;; initialize the global variables that hold patch agentsets2 V  i+ C8 R; n  {  J
  set roads patches with& K! S  v+ j4 c0 {: ~, _% n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ ~8 X' S3 p+ I" {/ o$ X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 C8 l# j1 e! ]5 W  [4 O' f: ~- ^  set intersections roads with0 p5 E" N% k9 W6 e1 y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! E" `  ^+ @1 K) A  B  Z; d* O6 v" i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 {9 |" `- X$ }& P; h
8 F: Y' l* d5 l# w
  ask roads [ set pcolor white ]8 }( A+ E7 n9 Z3 [
    setup-intersections* o1 j: [1 c* B- F" Y
end
0 E9 }# L4 l- p! s. z& F其中定义道路的句子,如下所示,是什么意思啊?% S  f- C# V3 ~$ q  d% J0 ~
set roads patches with
% ]& ^& R- u! E# L! q    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* P' l8 y. M4 i+ b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; q+ l9 e: T9 q0 d9 L$ O" h* A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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