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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。! S: t. S7 g4 }, z. D/ T2 B1 E' U
netlogo自带的social science--traffic grid这一例子当中,. r( ]8 c4 F, x8 k/ r, H
globals! a0 g! j! \# h
[
* g: p/ T3 G2 O3 t  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 {& t# J- t6 v
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# n8 z. d" \. B) E% M6 w
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" @, r* O$ _0 t6 X4 C, u                           ;; it is to accelerate or decelerate
/ g6 |. d; v! o! S" f7 o. e2 T  phase                    ;; keeps track of the phase
- m/ |: k+ }7 h' V+ G6 ?% H  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure8 }$ t) G/ j( e' ~5 X* |) M0 [
  current-light            ;; the currently selected light0 ~& t( d3 _) u* ]$ W- j+ `+ d* W
8 ^. b5 b0 E+ `1 G& f
  ;; patch agentsets
7 c6 j7 p" L) W& W  intersections ;; agentset containing the patches that are intersections
% b; H& ?, {7 F  roads         ;; agentset containing the patches that are roads* q& K6 M6 ^5 i
]1 h6 v) O* s( |5 h# \+ r2 ~+ q5 ]4 A+ P
! F9 @' }* v+ i4 y) B+ n1 A) P8 t
turtles-own  i) s: c- X1 t
[
0 R: E0 X. Q7 E" Q- V+ Y( @. \  speed     ;; the speed of the turtle, w" l& s7 I5 t8 _: K2 S: T* H
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 F( i/ e! C* Z9 a6 v
  wait-time ;; the amount of time since the last time a turtle has moved2 n# l6 U, |) q' X/ x+ @
]0 ?' J' F4 b+ n
1 @) {. S7 N, d$ \
patches-own7 L8 T. Y/ p+ A6 M! S
[7 f% Q) T0 a4 L, y' Y3 v; r: B' w
  intersection?   ;; true if the patch is at the intersection of two roads4 N1 [; y6 D5 s
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% H6 O8 G, m$ v
                  ;; false for a non-intersection patches./ _5 W$ K0 s: B: Q
  my-row          ;; the row of the intersection counting from the upper left corner of the$ [8 d. f( ]4 M9 `+ k: r
                  ;; world.  -1 for non-intersection patches.0 u% g; Z" w7 k% [6 F& z
  my-column       ;; the column of the intersection counting from the upper left corner of the; H3 j% p& X1 ?8 C
                  ;; world.  -1 for non-intersection patches.
0 m6 h: H: A1 @6 j6 ?# N: h6 ~4 \) ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 v2 V: A$ c, l  auto?           ;; whether or not this intersection will switch automatically.
; b/ y9 R# N5 p                  ;; false for non-intersection patches.
  n; b( h9 z9 O]. \4 }# u" ]. j; e5 j; ~
! b: J& ~  T8 |7 X
" T' o' Z8 n+ W# p/ s8 H
;;;;;;;;;;;;;;;;;;;;;;- s! C" E4 V8 {; C
;; Setup Procedures ;;1 V; `) [  w0 t9 A) @  w
;;;;;;;;;;;;;;;;;;;;;;9 z' [1 o8 B1 M: J/ v4 t

- u) B' K: b5 D) ^6 l;; Initialize the display by giving the global and patch variables initial values.
$ X1 l0 k/ f9 E7 d4 z;; Create num-cars of turtles if there are enough road patches for one turtle to1 K2 q+ B! a5 b) A
;; be created per road patch. Set up the plots.
& s1 ?( ~8 G+ ?$ ^! M5 lto setup
/ D' _, [: T9 P, s$ p5 U1 i9 g  ca, l( M1 y. T% ^7 Y2 a1 b
  setup-globals
5 U% ^1 k# \+ e4 R- O! s, m; |1 K7 g. ]8 b
  ;; First we ask the patches to draw themselves and set up a few variables
2 t! i6 M) O% p% n% D  setup-patches
  z' x0 _% s3 J6 ^" b, d  make-current one-of intersections
" f/ l* k) S6 v# b* t6 S  label-current5 d3 l( R; Y$ f" O+ d8 u, {
/ q; L. }; n8 h' S% Y# ?. `( Z8 b: z
  set-default-shape turtles "car"# c2 k6 X% t& j8 R- J% G
' ~1 J+ r, }- ~% N* Q5 ^, m
  if (num-cars > count roads)
+ z2 G' F0 l6 H( V, z  [2 r; e6 \4 z% B" w$ e  X: f
    user-message (word "There are too many cars for the amount of "/ D/ J3 L  ~$ |3 R3 ]& h
                       "road.  Either increase the amount of roads "
4 {+ o  b$ P: E. [                       "by increasing the GRID-SIZE-X or "
9 W- W* i* b# L8 v+ W* W                       "GRID-SIZE-Y sliders, or decrease the "# L0 A- a" e/ d7 o( b: J8 U
                       "number of cars by lowering the NUMBER slider.\n"
* i4 P8 b6 d* L5 K  P( N                       "The setup has stopped.")6 C( F+ [4 n. ?
    stop
6 M6 d# l. D* _% A4 m  ]2 m$ ^1 v6 d1 }
) b1 P# n; |; M3 \$ m2 h
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color% T- ?- B  j! f* `4 C4 R* [# I5 O7 m0 n5 f
  crt num-cars
" |: p0 x6 O) _: G3 \$ |8 x  [2 d! w: x; |0 J7 ]. \0 E& ~
    setup-cars
$ M, n3 L, [" n3 u2 ?/ ^) S% l    set-car-color" v$ Z( l7 g4 W, i! c
    record-data& d; `) @7 j5 B4 u1 H$ q" a
  ]
( k; R! w0 O* ]( ^& `  Y$ y& h, V8 z* l' }  p! ?; C
  ;; give the turtles an initial speed4 O3 M- Y% A: d& V# |, D& u
  ask turtles [ set-car-speed ]4 R; z6 x' P6 j1 D( p" K2 U+ y
& r4 `5 Q3 y0 V* ?+ R
  reset-ticks
) z7 p# W) y% {4 C% V+ Vend9 c; `' ?* T2 h! w
: v$ _5 h, d& l( o& f: m! b
;; Initialize the global variables to appropriate values
( [, @4 N* N' c" p) ?to setup-globals
/ c" p2 |% t; O" G  set current-light nobody ;; just for now, since there are no lights yet
) P3 ^* J6 G" N  c  set phase 0
( ?" k- r" e$ T) Y8 w/ J' ]  set num-cars-stopped 0) J5 k6 v$ Q1 W$ z: C' g
  set grid-x-inc world-width / grid-size-x  _+ j) ~" T( k
  set grid-y-inc world-height / grid-size-y
+ \* m* X/ X- h' R+ z6 R5 y+ n4 Q" `$ V  V# U9 M5 k+ J' O; z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) _  k. i/ b- R4 D+ a  set acceleration 0.099
' r" g% f) j* Q) e6 V5 k/ dend% v- g+ J0 p! M) J" I

8 T% g0 d5 ]7 @4 M/ N- n9 M9 E, E8 ]" Y: V0 h;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ B: T, h: g9 q$ d7 [/ d
;; and initialize the traffic lights to one setting3 x5 X+ d, ~  H# W5 A  j
to setup-patches1 {* M/ I8 P2 u, t- R( g% |
  ;; initialize the patch-owned variables and color the patches to a base-color) v$ y' c( A/ z1 l1 I$ V
  ask patches
2 o; G% s5 Q* z: M" n) E  [
' R- @) E! A! p    set intersection? false' X9 T$ w8 C: f( `: E$ z
    set auto? false# W+ b& z& U: n% b3 ~
    set green-light-up? true: Y- {- b! j9 z6 a( T" J4 f
    set my-row -1
" e0 b1 j" p6 b' b    set my-column -13 E0 c$ {* L; M- [
    set my-phase -1/ v8 }3 R! ?! E0 t, T$ b- C
    set pcolor brown + 3  l) W% U0 ^7 w
  ]
2 U/ }) e) A$ f5 t5 \1 |* _! x( S, R* f* G; k
  ;; initialize the global variables that hold patch agentsets4 Z: \3 }- \9 }# n6 M* ~. f
  set roads patches with
3 y( S% t6 f1 i, Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* ]' W9 N! x, k: T9 X# j$ x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( d; b  \! G! v) {; r
  set intersections roads with, F& A+ ~8 a2 s1 E  L; U4 a& ^: a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
1 v5 Z8 d0 N6 O: Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 ~& F- C$ X) a' {6 e
: f8 Y2 K" A8 B7 N# |! D  H
  ask roads [ set pcolor white ]
/ R3 {/ X& B, p1 @    setup-intersections- ?0 U* `/ A/ O$ C- \% i. b! C
end
0 k7 a0 D7 t+ }- G; `其中定义道路的句子,如下所示,是什么意思啊?
1 F+ Q( t1 t* _/ D" J set roads patches with/ \' A4 x5 E( Z6 @" B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; p3 a3 [& Y$ T4 g- O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 c$ L0 l7 K" w' z" B4 Q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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