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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。8 a" m% M9 V! ~
netlogo自带的social science--traffic grid这一例子当中,% e7 r4 p* F6 }. U& Z
globals
2 t8 a8 w; [1 o) X; b[
& {: \, E( u9 J: @+ {# c0 }/ U  grid-x-inc               ;; the amount of patches in between two roads in the x direction, w/ y& d" R' ~* I5 i
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ V: }! _4 |7 l; F9 k
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& H* F' }  y6 _& D& w4 p$ b9 q8 Y                           ;; it is to accelerate or decelerate4 f6 G& [. y% V* v& p5 q) C( O
  phase                    ;; keeps track of the phase- F$ K9 y  v* j
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 _: a' ?$ \: }  C( y% G& x
  current-light            ;; the currently selected light
, C+ |; L7 z# \4 [
2 |  ^- u. V' m' V( ~8 F  ;; patch agentsets6 p7 H: S' w5 v: D0 i* \
  intersections ;; agentset containing the patches that are intersections7 U- K4 [* f/ `% X% @  ]
  roads         ;; agentset containing the patches that are roads& R4 l0 Z2 T8 e6 ?" x2 E
]
, v5 C* Z; B% t; l) A: I% X3 s8 ]/ E  B& J9 L+ \; e% c! z
turtles-own
: [6 H5 d; N: K- K/ `[
6 d! p& |  }2 |0 S  speed     ;; the speed of the turtle4 a( v' Y4 y7 Q/ A9 ^" t4 K
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 @# v, A; i% {$ [% E  wait-time ;; the amount of time since the last time a turtle has moved. \: K0 }4 t& [4 _) j/ c( Z7 J
]7 e; C. N4 m1 s
. X1 y3 f( [3 N3 I7 ~
patches-own
5 B$ V( W4 l( Z0 w& L, \! t- @; H[6 G( G( K$ m* f2 D5 J, k# `% p
  intersection?   ;; true if the patch is at the intersection of two roads  V  W0 F% ]3 S: k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" D0 y( D2 n) x                  ;; false for a non-intersection patches.: w# |2 V1 S$ R
  my-row          ;; the row of the intersection counting from the upper left corner of the2 V* V6 c4 e, s4 o1 o
                  ;; world.  -1 for non-intersection patches.
% g& D4 D4 k# ?. [1 Q  my-column       ;; the column of the intersection counting from the upper left corner of the; \: V7 n* b( h- A/ i0 u6 F. m4 T
                  ;; world.  -1 for non-intersection patches.
3 z+ w3 ^/ N& m# g; \  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( a0 S# Q1 b2 t* a  auto?           ;; whether or not this intersection will switch automatically." f( h! ?- [: |9 E; Q
                  ;; false for non-intersection patches.) u9 i) n& Q. O) f! p, i9 u* x$ L; n( V
]
% Z* a3 {5 |, _" {6 _- a' d& ]8 k& v0 k; F, j$ V

: r; }0 y1 ^$ @;;;;;;;;;;;;;;;;;;;;;;0 c+ `) j- t! Z2 a
;; Setup Procedures ;;
- M! e! T2 F& C( Y) y;;;;;;;;;;;;;;;;;;;;;;8 ]) c# P% @# a" V( F7 I% e! B

3 _& x' q! `$ k$ c/ m* U;; Initialize the display by giving the global and patch variables initial values.1 c8 p5 S, e$ X/ X; ?) u; _7 e
;; Create num-cars of turtles if there are enough road patches for one turtle to
$ c7 U9 Z+ Y1 E0 Q. Q- @2 K;; be created per road patch. Set up the plots.8 `" C8 p; ~. F
to setup9 ?# n3 O$ K; t+ W3 N
  ca6 Q. e- {; [1 n# a' v8 T
  setup-globals
- ~: H+ h/ K8 \, `% i0 q0 K
( m) j$ x0 T3 I  ;; First we ask the patches to draw themselves and set up a few variables
! S2 H) l: L' E# v# E5 a8 U  setup-patches* W, a5 @* |2 l6 _) j
  make-current one-of intersections
2 J% G! _, |1 s. Z  label-current
* u0 s1 }* C* {: p, s7 ]( r2 l
! A/ a' E# V- z* d3 k3 [  m$ C  set-default-shape turtles "car"
1 ]/ C  v+ R  j% c
, B5 f0 q  u6 Z/ v/ f  if (num-cars > count roads)
% J$ c: s* T' K& F  [
% j4 f' `# l8 n. r* Q5 J1 u' \    user-message (word "There are too many cars for the amount of "
1 @; \: P1 ~6 ~                       "road.  Either increase the amount of roads "
  y) B  E& [+ j+ Q& K  q  F                       "by increasing the GRID-SIZE-X or "
, P' b7 |' X& G- m  X! j                       "GRID-SIZE-Y sliders, or decrease the "
$ n- o- i  P, |1 n. L; z                       "number of cars by lowering the NUMBER slider.\n"
. x/ |8 r% J" z' _9 S+ R3 w, Y# g                       "The setup has stopped.")6 y: c+ _2 ]6 B* @
    stop, t- ^5 T$ u. M9 x& l
  ]/ [1 S, j, S# _. N7 }) e+ |% ~9 n
1 U% d, k% Q, f8 n. S7 x/ P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
/ {) u* ]& j9 R3 p: F' O  n  crt num-cars7 N# K6 r4 O! `* J/ c
  [7 \4 X6 {% o$ A
    setup-cars
1 P4 t* p* O* B8 v    set-car-color. K7 ^& t+ U: M
    record-data
4 {( B- O% L: v1 ]- n  ]. R; Q) J9 x/ j1 o# r& P1 v
' C9 W# d& |, H( a* \8 _
  ;; give the turtles an initial speed
( q, j' i0 e: e* M/ t* e  ask turtles [ set-car-speed ]
5 X" X# r+ x& O5 O" ]3 Y- H3 Y3 p" R# I( M0 N7 x
  reset-ticks
3 ]+ ^+ k( Y3 O9 o# iend
' B% ^% {* R7 ~" _
& G- p7 y& J4 W2 Q7 ?1 P;; Initialize the global variables to appropriate values: f6 G6 D' Q% u" t' Y: A$ l& M
to setup-globals$ b' @8 G7 d/ a) G1 Y/ H' ~
  set current-light nobody ;; just for now, since there are no lights yet
0 m- o4 |" W6 {- K6 a* w9 L7 T3 s  set phase 0$ S  j6 [5 B" Z" N( L1 j
  set num-cars-stopped 0- N0 Z8 h1 l$ _6 @) d# N
  set grid-x-inc world-width / grid-size-x
- u8 N4 k! t1 }' s6 V5 c  set grid-y-inc world-height / grid-size-y* Q% D* b+ }  G, h

- K* p1 e& A1 A6 e$ [" m) l# v  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, Q1 r4 C  w- }6 f8 L
  set acceleration 0.099
' ?9 V- {1 v2 {5 U, Y8 b' |end
. z: F3 A: Z  j7 Q9 F
" f: f# W3 J1 m6 h; {/ b;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 `! C3 x( M6 e, I: @
;; and initialize the traffic lights to one setting0 j, X# q: M& r; g+ Z% z7 ^) |
to setup-patches
% v" Y; L! |' l2 o% m  ;; initialize the patch-owned variables and color the patches to a base-color* m( n$ }7 ^1 V7 O
  ask patches& V% {  ^+ J+ `' o
  [
. ^$ f& b; y5 C4 f; j    set intersection? false
; s5 A5 l& A6 k* w! C3 T    set auto? false
$ T$ R  A  r# _& L! \  I+ b9 O    set green-light-up? true
  y: C) |' P3 j& d- D    set my-row -1
/ i& p4 S; k- U# q) z( ?5 p    set my-column -1$ z. A! Z# y1 C( ?1 U
    set my-phase -1
; r( B7 i3 o4 \) h/ F    set pcolor brown + 3' t8 ~0 k- y$ P' l. J, F
  ]/ ?. ?# H8 y8 D. k3 {& z
) f; \" S& A) q) P2 n
  ;; initialize the global variables that hold patch agentsets
, X- b& W6 |. l% Y$ H. Z  set roads patches with' Q+ n8 w9 d0 A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 ^5 K) _) n: f8 o- ~    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& N5 k6 B+ I% y
  set intersections roads with
. z+ j7 t; T0 S7 t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# ]$ Q3 z' c4 k$ Q) ~% m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 G" J5 r* [2 X- V! V
! V: m0 k6 K1 `  ask roads [ set pcolor white ]
1 T. U0 G- H$ o) E    setup-intersections9 t2 \6 T; w# Z% j0 M0 B9 ?+ c
end
, ?( q8 S: O: C其中定义道路的句子,如下所示,是什么意思啊?
, a& t' G1 N0 ^# {4 E set roads patches with
( c$ T, b0 b$ I0 b, C: t5 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, D+ O2 g6 o8 L8 H; _$ G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  l8 }$ s0 t# l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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