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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。6 A! O8 [3 |  v5 T* S( T  w  i
netlogo自带的social science--traffic grid这一例子当中,+ k) D; p" n0 B
globals
: I/ A; h  _$ ^& C4 T8 l[: N0 U' R! k# e: E. l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction. a5 y2 g# u& g/ Q9 p$ t
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' f3 H+ @5 ]4 `7 ?+ @2 V8 Z6 {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& k) n# L: n) y& m" I- n
                           ;; it is to accelerate or decelerate1 M8 \4 I; @7 h* M  F5 D$ R
  phase                    ;; keeps track of the phase
6 s/ N; Y5 @6 e  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 G$ b, b. A! w1 Q) n5 h% S  current-light            ;; the currently selected light
/ ^; `8 ^! L7 V- y+ W  h9 d
8 v! H) q0 S' S+ G# V) n& B  ;; patch agentsets; y9 c: u6 F6 ~) W( d6 k' Q
  intersections ;; agentset containing the patches that are intersections" |  ]* q9 Q$ Y' z
  roads         ;; agentset containing the patches that are roads
4 m; S) F% F2 j* l8 i1 q7 F]) S, F" @9 ^# |6 k' L
5 j* V8 C' C: i9 Z
turtles-own
$ X0 E! B8 t& ^' D0 U( S[% \3 {2 P5 `3 v- L, I
  speed     ;; the speed of the turtle
/ w7 Q5 Y/ \% v  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 {4 \1 q& `( ]# V' t1 G9 E
  wait-time ;; the amount of time since the last time a turtle has moved3 B' Z- }# |0 u3 `
]8 n6 U! m! F2 p/ W  O

5 m0 Q8 i) |6 h) j  x5 H7 L8 q. l1 dpatches-own  E$ r* t  }4 o' k: k
[! A; o# p" n7 e5 D2 g: E3 H) H
  intersection?   ;; true if the patch is at the intersection of two roads
5 E, @, @9 A  K6 _7 N  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: c+ i  d3 D+ K* z- U
                  ;; false for a non-intersection patches.3 n* t) R; F/ ^" d: E# w
  my-row          ;; the row of the intersection counting from the upper left corner of the
" d1 o  s6 n7 ], P$ H7 q0 ]* b                  ;; world.  -1 for non-intersection patches./ X. j- I" U: p# [' S
  my-column       ;; the column of the intersection counting from the upper left corner of the
1 b8 F8 l4 a1 Y& k0 b, x* j6 Z& M                  ;; world.  -1 for non-intersection patches.
. @8 o/ E1 t* o9 }; h7 D8 i( u) }  o  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  r/ e- h8 ^9 ?0 a; Y
  auto?           ;; whether or not this intersection will switch automatically.
" y) S: ~" a& a' Q4 t' S; J4 ?$ }% z                  ;; false for non-intersection patches.
0 e) l' L& B4 }8 o+ a]
" E' y) o* b/ }
/ i0 s1 S  Z3 J* R2 S
$ ?- W6 G+ g7 A2 S# t; r% Y1 t;;;;;;;;;;;;;;;;;;;;;;" P' Q; Z+ h$ K) \- H( Q1 v2 |- v
;; Setup Procedures ;;2 _+ z  n, @! v/ W6 R
;;;;;;;;;;;;;;;;;;;;;;. [0 S- Z/ d) I! u

9 l* Q6 N# x* f5 G;; Initialize the display by giving the global and patch variables initial values.
( x7 k/ b+ o6 @4 j;; Create num-cars of turtles if there are enough road patches for one turtle to* W8 R# `5 s- ?2 Z. I/ f9 R/ n+ C$ M8 J
;; be created per road patch. Set up the plots.
) _+ r( S4 ?2 Q5 g4 p8 j! vto setup. ~8 {- t8 d2 ?& e
  ca
4 Z0 Y9 x) X! L5 S: i9 x  setup-globals% ]! |& i& }( x3 a
3 T( T& J; c* q" L+ l2 S- p
  ;; First we ask the patches to draw themselves and set up a few variables& I! k' j" E; g: e& Z
  setup-patches& T. B) j1 G; h3 n
  make-current one-of intersections9 b' d- b  j" f  G
  label-current, t/ @- K& C2 \3 N! _) I

$ X- d* ^$ k' ^! W; ^% E5 R  set-default-shape turtles "car"; z- L, C, ^7 F

% r. p+ S% {, U. m( k+ T  R. C  if (num-cars > count roads)
  R' ~7 n' C( W* P2 g- A  [- I: C0 X' F: y& x% G- W
    user-message (word "There are too many cars for the amount of "
7 w! q) t8 o; z" G- G- K                       "road.  Either increase the amount of roads "4 {, l  g# a. J* \0 s+ G
                       "by increasing the GRID-SIZE-X or "
5 g: ?6 L) B; r* x, s7 a                       "GRID-SIZE-Y sliders, or decrease the "
4 R/ M1 U7 B  \  g" ~$ }3 _                       "number of cars by lowering the NUMBER slider.\n"3 w  {4 \2 S- ^. B
                       "The setup has stopped.")3 Q) m! L! H" i$ T! }' E
    stop
8 F% i. B* t  f) U% y0 x. y  ]. A# h. \, U/ ^) p4 s! r2 o

* R1 Z" B, E4 C1 a- u5 v" @  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( B# {. d' [% x2 k, t3 _
  crt num-cars3 z. B  g5 l8 @
  [
+ c/ H5 c7 q  v$ S+ a    setup-cars
6 A7 a, N0 Z( o    set-car-color
8 W8 r( }2 |7 f5 Y2 k% S    record-data
# j! E" [0 I2 j1 @  ]
7 R' t+ r& N& i  s) b0 b1 p/ {* ]/ s+ V
  ;; give the turtles an initial speed
2 c1 R4 _: E7 n# k  ask turtles [ set-car-speed ]0 ^/ E5 L" C$ C8 N( f* M6 d
* m' i0 \5 B& |
  reset-ticks
/ O- E. }, {3 [/ `1 iend: e- m4 R1 d- U

) _# m- P4 b$ {0 K;; Initialize the global variables to appropriate values
3 k3 S% D: {% ^. C1 i  Lto setup-globals: ^) u* O+ X6 ~0 M+ A+ j- H
  set current-light nobody ;; just for now, since there are no lights yet8 f8 K) x# |: q; N
  set phase 0
1 e) H" R2 [( c  h+ a/ Q1 m7 s0 O  set num-cars-stopped 0
+ B! B4 E# B( v8 w  set grid-x-inc world-width / grid-size-x
0 ?" E- k& F* ?# l2 P8 W" C  set grid-y-inc world-height / grid-size-y% G0 R  p3 w9 B* X
+ A1 u% O$ R9 [9 m/ b# |
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, `4 O6 @# ^& J( x! R8 D
  set acceleration 0.099
$ Y( s0 _: t: Q/ @end6 T/ O  T. L# X; X# p

: I2 i3 ^% R4 x. W, g& E;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 E' b; o8 r0 E  N" r4 T0 |;; and initialize the traffic lights to one setting) q0 [, [5 A- K' C3 P
to setup-patches; G2 s5 Z9 r- t: e/ I6 N* r2 Z" y
  ;; initialize the patch-owned variables and color the patches to a base-color
2 `$ W+ S! A( r6 p( i$ f  ask patches
; X$ W% [* t# }, e  [
3 x1 V, E' w6 @4 h% G    set intersection? false
+ ~$ v$ }' @8 p4 K% P2 B3 Y    set auto? false8 s  z7 ?; _. ?* }# ^
    set green-light-up? true6 {2 E( i( c: s6 _
    set my-row -19 _/ F* h7 V! D" W8 W$ J. P
    set my-column -1
$ O. v, X, H, M$ F6 [8 n    set my-phase -1* r/ f0 Q* c, [1 ~$ C7 \6 Q4 s
    set pcolor brown + 3
' K7 q) B* s" t" K2 c7 o+ j  ]: z5 ?0 n1 @' ]+ ~

9 C/ f4 }2 F) [5 p+ U+ P  ;; initialize the global variables that hold patch agentsets0 c. Y3 w5 t# f( z: L9 o# D4 {
  set roads patches with
% x7 T& o2 s8 W0 B% s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: }) a5 `  ~) P  M! e& W. `8 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 ?: [# n4 k3 \4 G! U" u0 ?3 ^  w+ @  set intersections roads with: E$ @4 K3 B; `5 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 p7 i6 M* z5 a3 [! ?' k9 f, k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& B) \5 K; V9 d1 H: U) z7 |; G

3 H7 S, {8 S  k  ask roads [ set pcolor white ]
" [# O* H  l8 ^! a    setup-intersections9 B- W$ ?' C. ~  S9 J3 H
end
% a7 H/ O( ^+ k2 p: j其中定义道路的句子,如下所示,是什么意思啊?% \/ L; J  b1 k7 e) g2 X; H. ^- L
set roads patches with2 O; U" B* ]1 `9 P( O: v' n) T* I9 N+ |7 J
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 o/ Y6 e3 j  Q2 b# _, {) d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" j9 s* L( Z- g. X1 N! 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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