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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。
: C- n3 h  s; unetlogo自带的social science--traffic grid这一例子当中,
8 S: V0 e0 }& |1 o- |globals$ m  ]% ?3 u; d9 M2 v
[
" O9 _& @0 ]( H! m) w/ `+ x  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) q7 B* q& q' v. R' {) u( Q, _3 a0 }- A  grid-y-inc               ;; the amount of patches in between two roads in the y direction( X2 D& x. Z) {& I: [) x/ ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 l- _3 x6 y+ _/ X1 r/ ^9 q; A/ v( p" d                           ;; it is to accelerate or decelerate1 x5 F, p) F: B- v( |! T9 z2 h! F
  phase                    ;; keeps track of the phase2 Q' @2 d" r: ?( r. W' z1 i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, F* ^  n8 b. t2 _3 @" D1 J
  current-light            ;; the currently selected light# I( u; ~/ H  f  g/ }& C. m
) \/ P  L0 X4 b2 |- ^
  ;; patch agentsets. _% r7 `8 I; S7 _, m
  intersections ;; agentset containing the patches that are intersections
; l6 y! v2 f  N& O+ G  roads         ;; agentset containing the patches that are roads
4 o7 |" O6 D4 ^. c, I( ~5 v]) D/ @1 F/ x- x- O+ g7 x2 @
: t6 I# D5 b$ X- p
turtles-own: ^9 @9 M, T7 \3 ~3 R/ R1 a
[
) j+ _& B0 u0 j: j3 {. E; O  speed     ;; the speed of the turtle
8 {: N# D! W8 H. V  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, b* [( F2 m7 y5 r; M% l6 \1 A* _  wait-time ;; the amount of time since the last time a turtle has moved
# a/ u5 @6 A, K1 M7 R]- K) M, [5 \5 \, y0 U# K

2 L+ T0 P7 x" t( w. Fpatches-own% f4 V0 u# N6 L, x; U2 k. s$ }
[
. }# C4 |* G. {* p9 W0 z  intersection?   ;; true if the patch is at the intersection of two roads" ]1 g6 m# d4 E: M# ?3 ~$ \
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: L* e( N5 R, E7 \5 G; ~% T
                  ;; false for a non-intersection patches.% p. x9 w& D- E. v& X
  my-row          ;; the row of the intersection counting from the upper left corner of the
1 \8 H; ]# f; u3 ^                  ;; world.  -1 for non-intersection patches.
& j5 ~8 u( }8 e' c/ ~. L  my-column       ;; the column of the intersection counting from the upper left corner of the
8 d& x" o% ]1 R: j- Y' a                  ;; world.  -1 for non-intersection patches.
1 y/ X( j5 u( F$ `  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
- b% h! r, {6 [" E" \  auto?           ;; whether or not this intersection will switch automatically.! a" ^2 D% K2 _8 |/ i- ^; y
                  ;; false for non-intersection patches.
9 _" e; [9 _3 U]4 e) t6 }4 W) h7 Q! I
8 @  u' ^4 ?7 V( Z/ K- Y5 d
( c6 A2 f) b; u% u, R' {' _9 B
;;;;;;;;;;;;;;;;;;;;;;
( s5 s7 x9 ]) L/ t: w8 {4 F;; Setup Procedures ;;
6 J6 y& M! j' r8 y) k- M% j' \;;;;;;;;;;;;;;;;;;;;;;. p5 D# e! }3 M. Q" X
4 C- S! U# X$ p9 k. P
;; Initialize the display by giving the global and patch variables initial values.
' G$ t9 u" W' K7 O' O% s4 X;; Create num-cars of turtles if there are enough road patches for one turtle to/ G& i1 {- c) [  D5 G2 O+ W+ z
;; be created per road patch. Set up the plots.$ P) M0 p* I) F2 R' u- k
to setup, Z+ y# O* \0 x7 |4 T4 v0 _2 M, j
  ca' ~4 a& Y+ \$ T  m% S$ H3 `3 N
  setup-globals0 ~& m5 q0 x. U
* _( k0 ]1 D* x9 Z( f! r0 q/ y
  ;; First we ask the patches to draw themselves and set up a few variables
/ O% w: z/ {9 e- W3 y6 s+ o  setup-patches
. V* l9 }! T6 \2 d7 Y  q  make-current one-of intersections
& S+ o2 a3 {8 C5 Y1 Q& p2 T; P: f  label-current
2 x* a, v/ Z' \/ g1 v: v" \( Z* Z6 `, d4 Q- q4 U( |2 B! J% B9 f0 M9 k
  set-default-shape turtles "car"6 Z: H$ _  g% u4 O# F; D% e

* O% J1 b3 t. s" J+ p- p% i  if (num-cars > count roads)7 r' J4 H" y4 R8 v
  [
8 i- U+ e0 C, G0 i" D! M8 L, d* h    user-message (word "There are too many cars for the amount of "$ B: X7 _: Q. o, c
                       "road.  Either increase the amount of roads "
2 G3 b' r) H3 c) T                       "by increasing the GRID-SIZE-X or "! ]- J) y7 s' V& ~4 J, N
                       "GRID-SIZE-Y sliders, or decrease the "* v, M4 Z# L/ z! x) h5 W: A5 y
                       "number of cars by lowering the NUMBER slider.\n"
+ z8 o3 C. g/ k/ h; x                       "The setup has stopped.")' Y1 Q6 b+ ^- F5 \9 o: R8 j
    stop7 Y2 _! p$ m3 R9 d5 v3 {
  ]6 W( Y5 E2 ^: }9 m. G! D
& X% b6 ?( S6 f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; ?: p* F  X, c& n1 p  crt num-cars
- V' U  ^0 e8 F  [4 w! D$ @% T/ }: v0 [! j2 k% R3 \
    setup-cars
- B6 l% C! _0 T0 `& I    set-car-color
/ U" x4 a! b: k; D* ]    record-data) N4 @- {: n4 W8 x0 B% ~
  ]
) q9 H$ }+ _6 O' h3 |" ], h- N
0 c, t6 n( l* H$ ^  ;; give the turtles an initial speed
0 e: n# N* K. g7 v) s5 i  ask turtles [ set-car-speed ]
/ i( Y7 O- y  F, X+ T5 ?: [: y
5 A. d# q2 l  T9 y) W  reset-ticks
! ?% H: y% b% J( n( Pend  I7 H- Q* s  ], ~0 y
$ _, U/ k/ i: d0 t
;; Initialize the global variables to appropriate values) ^. |9 H) W6 l9 W' J
to setup-globals$ _/ ^8 ~/ W! I: I' }4 V
  set current-light nobody ;; just for now, since there are no lights yet6 r1 t" o) m+ k8 Y# p( `
  set phase 0
$ o2 Z  A2 U3 r$ d. b9 E5 r  set num-cars-stopped 0' d" Y+ Z% ~* X, K3 z- c
  set grid-x-inc world-width / grid-size-x
6 N5 Z! U4 `0 h. d8 y6 }3 v  set grid-y-inc world-height / grid-size-y6 z6 y$ ]- x$ Q: s/ _) a- G' l! d
# @' m# \1 y2 ], S/ M& `- w
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 S' M1 Q2 I. n
  set acceleration 0.099% V. p$ s, [3 s+ ^) q, i  z# F
end# @/ c1 y5 n+ V6 A2 E

( U$ V2 A0 l9 _+ J8 u- f& W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* ]$ Y% ^3 v0 L+ w0 `1 L+ U
;; and initialize the traffic lights to one setting
) s$ n4 N, W) Z. }7 P: Kto setup-patches
) L9 l- ~/ H, v% C  ;; initialize the patch-owned variables and color the patches to a base-color
- s. Q/ Y4 v7 O( z. h% \  ask patches9 D% o4 c. u" m8 h8 q$ _: ~, G; F+ \
  [( y# {, n6 @( Q- F7 D" m$ j+ Y
    set intersection? false
3 g/ g5 q. d: `2 T4 J& _- `, i9 Q    set auto? false
* R& {1 k$ N* }/ B* @6 G8 X& O    set green-light-up? true
8 P1 g: h. ]+ h! q+ c7 r    set my-row -1! |1 i- |0 L0 Q) j
    set my-column -1
9 t7 N0 J" J0 X! Z9 l8 q5 ?3 M/ _2 X    set my-phase -16 {) B; k; B/ x! j
    set pcolor brown + 3
# c1 |: I2 V  e9 h2 g6 S% \  ]9 G- z4 N( ?" d" U8 y) a& t  E, F8 z
9 B* Y5 n( P& N& c( M+ [5 o
  ;; initialize the global variables that hold patch agentsets
- X. D2 E2 o6 u$ [0 Y  set roads patches with
; s1 I9 J0 ?# H- a, L7 K- I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 t* ]# C  Q9 C' h, A& w5 g  `8 s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- d" n! _" K+ f: f' z% t' T  set intersections roads with! S" g/ C# W! ?2 c4 r4 M
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) M. i( i$ c& z/ Y* x% n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& o) o3 k$ j( }# }' |: `

& Y- [, |% c" g% ~: s  ask roads [ set pcolor white ]
' K8 A7 K9 [( P/ Y3 Y    setup-intersections
0 U. h& n7 i2 ]6 n: iend8 S& a5 e; c% D, s
其中定义道路的句子,如下所示,是什么意思啊?
, n& \; K. L. x9 G set roads patches with
4 x# V1 O8 C7 y" w- x3 L( R% S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 c/ p( Z& a% l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 n4 W2 K2 p. ?4 F6 f5 j! T; u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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