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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。) n% \# `4 N; T5 ?3 h; s
netlogo自带的social science--traffic grid这一例子当中,$ @0 f8 B# }" W# Q( v% ]( [
globals& }0 n- V0 `; ~4 y
[
  m: M( v2 S6 n9 A& E) y4 ~8 w' A" g. f  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 @2 E, N1 ?' r  @# a& I. l2 G" g2 e  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& H% L/ w  c9 |! i, C- l, h0 }" T' n2 r  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; ~$ N5 k0 l" j) Z7 d
                           ;; it is to accelerate or decelerate' n* [' `# ]2 t" Y3 u$ Q" d
  phase                    ;; keeps track of the phase5 l! n# U, i+ Z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* g& b& Q$ I: j" `+ Y
  current-light            ;; the currently selected light- v0 m  w9 T) E' ~) _
; F/ ~5 }. V" T! p6 l
  ;; patch agentsets' Y- r* r' y, G9 }( k- L
  intersections ;; agentset containing the patches that are intersections  ]: N; n2 @: y- O3 T& v3 [
  roads         ;; agentset containing the patches that are roads
* F% X% o3 E$ S, P  k]# D" M) X+ i. ^  n3 a2 n" e7 Q

2 m. Z2 x; _0 a  L- V' Uturtles-own/ a( N5 q3 j8 J# b: A" h; u9 K% o1 J! q1 ~
[$ g8 c! [5 ?; `5 h1 s' R
  speed     ;; the speed of the turtle) M, E, Q  G2 v& d  e8 g6 E: h
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( \  s& r# f4 P8 i- W2 _
  wait-time ;; the amount of time since the last time a turtle has moved% h7 F- Y- Q' |+ x9 m1 W
]+ m9 p9 X1 _  [' Q9 ?- o. {

; a7 b* z3 f& `8 |1 o& F# upatches-own
6 C7 ~/ N" g" F9 Q) X  k: h' _' p[' V5 U: i5 t! {& u- U) T
  intersection?   ;; true if the patch is at the intersection of two roads" F6 h# k* x  C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( ~/ L+ @- J) G2 x) Q/ B                  ;; false for a non-intersection patches.
" U% |5 E: `  T, {. n. a  my-row          ;; the row of the intersection counting from the upper left corner of the% W: d' p+ n7 r- ^' M
                  ;; world.  -1 for non-intersection patches.9 I6 ^$ K" D1 R* q, A; j
  my-column       ;; the column of the intersection counting from the upper left corner of the$ @/ @3 X- G9 d6 o% w( [
                  ;; world.  -1 for non-intersection patches.
6 n4 s& A  |; i0 L8 W; O0 x  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! M9 O! M) m, C/ X. @! G  auto?           ;; whether or not this intersection will switch automatically.
, S% i/ T0 F% ~1 m8 z  `                  ;; false for non-intersection patches.0 f" d* p# u0 C, v  \  B2 N
]
- z# ~, u# f% U& p% n9 F  @0 m; \/ e+ P- \4 F

$ e  [4 V6 p7 w* R6 r1 z3 W;;;;;;;;;;;;;;;;;;;;;;
( r# K& I! M. I( K, N, L;; Setup Procedures ;;
4 o- C% N  `) n- d' F;;;;;;;;;;;;;;;;;;;;;;
" `3 N. t$ j) t( J0 a7 `) L( B2 A9 |
;; Initialize the display by giving the global and patch variables initial values.
' C+ @6 J7 A+ |- Y% H! `4 t;; Create num-cars of turtles if there are enough road patches for one turtle to4 @0 h8 Y. s2 j+ Z3 T
;; be created per road patch. Set up the plots.8 Z* s% \' a3 a
to setup; o$ R! m% ]+ ^' O+ t  ^: A
  ca  z1 T2 W5 _0 |( g! s& t0 i4 h
  setup-globals0 }: e2 {5 R7 @1 ]2 Q. n
. z: W1 ?/ J# w" U
  ;; First we ask the patches to draw themselves and set up a few variables
0 y6 A; |; ^7 l  setup-patches
' }  X2 S; T' @( x& ], y# i" }  make-current one-of intersections7 Q" C+ k) O8 t
  label-current
) R( [0 {- B! `/ l" ~! U
/ K9 E+ K8 a  K3 h% i  set-default-shape turtles "car". L8 n3 ^) \2 K( r

. g; q6 |" L$ _( m: c  if (num-cars > count roads)! j, ]4 q: B/ V, j
  [9 T/ v3 O1 Y+ F7 ^
    user-message (word "There are too many cars for the amount of "
- l( m/ ~$ I# L/ p+ ^  g1 m                       "road.  Either increase the amount of roads "
0 F" L( Q7 Q5 m" O  G                       "by increasing the GRID-SIZE-X or "$ z' ?& J8 W& e! t
                       "GRID-SIZE-Y sliders, or decrease the "+ E# h, Q: @% K. |2 D) U
                       "number of cars by lowering the NUMBER slider.\n"2 Y, J3 l. J  B+ S0 s' p0 l
                       "The setup has stopped.")( O: T8 l, a) q: a
    stop
3 i0 n. ]) |+ w9 H  ]3 @- G& q) n0 F4 Q0 i5 e

$ U& v; ]) w, F  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color/ v7 j# `2 ]+ N/ \
  crt num-cars6 k& f2 w% P) j! n
  [5 i5 h8 z9 u) ^* i  I
    setup-cars. @$ [; H# a' r" e7 d
    set-car-color
/ V7 ?9 E4 V3 n. F+ W    record-data
2 w% }+ T4 D$ c# n/ f% Y  ]1 \: J) P# J& n# x# A) i
0 f4 G  r9 m& X' D, Q4 P& m
  ;; give the turtles an initial speed* ~7 j# C: f) g2 }- K7 {
  ask turtles [ set-car-speed ]9 l; N( h( Q0 L9 S6 U% G0 ]

* _( R3 M) W4 R  reset-ticks. O/ i7 M/ B8 j* m* Y2 b
end
; u: ]5 `8 Z1 u" P( j! [. P: H
6 I# H# o5 ?6 [;; Initialize the global variables to appropriate values* S/ @' J. K! C* @
to setup-globals: H; w2 a* p! ?+ I
  set current-light nobody ;; just for now, since there are no lights yet
% T* b0 T4 W" h0 N/ B  set phase 0
# m" n4 @0 Y" F) g7 H& L% _' ?7 {  set num-cars-stopped 0
$ i2 `  L9 F* E7 y* d; w' @& l  set grid-x-inc world-width / grid-size-x: w- J" H+ n  ^: Y$ G- Q
  set grid-y-inc world-height / grid-size-y" m! \# z$ x" p  }
+ w+ Q. {- f; \0 |" f" f3 ]7 P
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
/ q' d( l/ N+ _% _3 T" Z  set acceleration 0.099
& R1 t+ h7 i% b8 Rend
# c% \! b$ c  s  x8 t  _; L
9 u8 b0 Q4 I$ [; J) p' Q# o* l;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ x+ B4 d6 J# M* g2 i
;; and initialize the traffic lights to one setting: I) N( B/ t3 c( P' |% A7 F
to setup-patches
* c1 J. [4 D1 J  ;; initialize the patch-owned variables and color the patches to a base-color
: `5 m( m! a3 U. F+ V! P  ask patches
9 Z- D/ t5 [; S' I8 t1 W+ ]% n1 {$ F# \/ Z  [+ X4 A# A5 E: O; v
    set intersection? false
* e2 L8 F! r. u    set auto? false
# {: }  M. {* T$ O: V) L    set green-light-up? true
8 f' w/ i8 u/ i5 A    set my-row -1
" ?/ M0 \7 I' V+ Q& ~    set my-column -12 m6 y+ _% m% J1 S: p$ j
    set my-phase -1
8 K5 x& f, P# r; J! a" e8 [    set pcolor brown + 3
6 D: R  A" @! Q6 H, o* X* T  ]
1 z8 O9 V; K, W7 F# Z2 q- U4 e( t" X
  ;; initialize the global variables that hold patch agentsets
$ n- R9 E; h1 Q) R% s4 j% l  set roads patches with
2 m4 N+ ~5 @  U1 U4 h3 Z7 K; c( O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: l) I( a2 S2 M) M6 `+ ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) F; |' `; I: x. }  p3 z  set intersections roads with
2 p, ?, B, b5 H/ t. H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
" C- D/ S* M; L) f7 O: v: x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 W& ~- N  Q0 w7 W* T
7 b) r/ f- l0 q* ~4 U# |, c  ask roads [ set pcolor white ]
8 X! o( ~* W; a' \1 k) {2 t    setup-intersections/ I1 q; j9 f* _1 c  S3 v, C/ x
end
5 X6 {" H4 l' P3 x9 p% B其中定义道路的句子,如下所示,是什么意思啊?
( j3 I& c, \+ u* m$ P6 z set roads patches with
1 i. x- S- s  i, U5 m1 D  i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or# ^3 {2 }' v$ ^' X: [. U' B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ I& J$ M7 J$ f; U8 m. x  e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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