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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。1 W3 d  y3 V2 |/ l( K, U! C
netlogo自带的social science--traffic grid这一例子当中,; H/ r0 D/ {" w! G: T* h+ M9 [
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 w3 A  x0 @5 H! M6 X$ j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% f1 L0 S  j# `5 |" T' \$ w! j: n& ?  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 G. |! |, B2 R% z
                           ;; it is to accelerate or decelerate! e1 p, v! o3 G5 s( }1 e
  phase                    ;; keeps track of the phase) ^9 O% }& Y6 S4 h. `
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' g6 i( c2 ^) r3 N
  current-light            ;; the currently selected light
- {5 n; B3 Z3 E, v( T3 M
; }3 ]1 n& w2 X; e3 P& A  ;; patch agentsets
2 ]$ q/ [2 t3 L" v3 x3 {* Z  intersections ;; agentset containing the patches that are intersections5 m1 _( l6 B: i/ {9 c0 J. Q% }: W
  roads         ;; agentset containing the patches that are roads5 J* o; R* E  h7 t, g4 i
]
" d) }: V0 O$ Q, D/ V* C/ V/ B- b: D% ^7 t
turtles-own
6 J) N7 S* }1 n1 Q: b[8 ?$ L. |) R9 }; d1 R; A2 L# Z# I1 S
  speed     ;; the speed of the turtle( l. q0 O/ }$ Q: E6 O
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: t! a) S8 r1 n4 `, o
  wait-time ;; the amount of time since the last time a turtle has moved
$ Z6 e2 U" F( o1 r, ]$ G, ^]
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patches-own
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  intersection?   ;; true if the patch is at the intersection of two roads
5 u$ H5 O6 k& F" E$ {, ^. u! F3 X  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 [' X$ L# |9 m: H
                  ;; false for a non-intersection patches.+ [8 m$ ]) \! ?- {+ G: F; Z
  my-row          ;; the row of the intersection counting from the upper left corner of the1 B, [3 W+ t  P' o: m
                  ;; world.  -1 for non-intersection patches.
0 d  w* C0 [% U, m  m  my-column       ;; the column of the intersection counting from the upper left corner of the
* M0 E8 D: n2 \& O- g                  ;; world.  -1 for non-intersection patches.0 \, j7 V5 [5 n( [! k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* D: Y9 V) u1 ?2 _! C3 c  auto?           ;; whether or not this intersection will switch automatically.5 y7 q, q6 Z" I. @+ `
                  ;; false for non-intersection patches.
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( \8 d( [( {8 g; f1 v) p  A4 D' R! O* F1 x& {, h
;;;;;;;;;;;;;;;;;;;;;;
- F. `- n& ]5 \/ V# Q. W; H;; Setup Procedures ;;
- ?; m3 g6 ^( b;;;;;;;;;;;;;;;;;;;;;;
7 [( @3 W+ p6 t' `2 R, Y; K2 U1 {5 ^# M" }0 R
;; Initialize the display by giving the global and patch variables initial values.2 \/ T  _9 n+ Y1 r2 E# F' n' A" [
;; Create num-cars of turtles if there are enough road patches for one turtle to
' b1 z2 I& [; z+ n  v;; be created per road patch. Set up the plots.
5 O6 D, i# o3 V) |' w: D7 k+ qto setup
0 ~' `* D: A& N, ?/ E  ca
; f/ k; F, s" ^- ^5 ]  setup-globals6 N* ]' l( ?% e8 G

; H" ?+ N4 V' E. B! J7 ]  ;; First we ask the patches to draw themselves and set up a few variables6 Z1 a6 _/ r) o( y
  setup-patches# d" x4 p: a: X
  make-current one-of intersections& ~6 T$ n+ e/ |# X, E& X3 x
  label-current) ~7 m  {6 G" _: `; o  x1 Q
' U' q6 D2 _' a
  set-default-shape turtles "car", A7 h/ p& |2 D7 ~- p' u
) e3 q& H7 E2 P* P# x, f! o
  if (num-cars > count roads)
/ N- |7 {7 K2 w. E! w; W& Z5 {8 r: G  [% H- @! c1 P. L  O9 r( c) M2 g
    user-message (word "There are too many cars for the amount of "- j( m- s5 g- C( u% E. u4 Q
                       "road.  Either increase the amount of roads "2 B# B( ^$ e: f
                       "by increasing the GRID-SIZE-X or "
  C  m5 D( {7 k& c. e9 Z' f                       "GRID-SIZE-Y sliders, or decrease the "
+ C+ e0 X' ?+ r+ z) }                       "number of cars by lowering the NUMBER slider.\n"  j' b( i; a- s/ b
                       "The setup has stopped.")% Q1 M0 n  \7 {
    stop; I  r/ g, \7 ^1 u
  ]
' p/ }; }* w9 _- s* z3 z4 ]2 r* Y; {8 G+ K9 R  ~
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. B! c# {" r! t- {$ {% t! n  crt num-cars
5 M) z5 S2 o+ `+ Y0 b" Q0 P. _  [
/ f, n) Q# E1 G1 e& n) l    setup-cars( f8 c4 `: h2 j+ P
    set-car-color! V7 ^2 p7 ?! [7 b
    record-data
7 q) n6 G5 |( w6 O. H  ]
1 B' H) H( l3 ]* W
! X4 [8 X& m& x9 N/ C. ^+ M/ m  ;; give the turtles an initial speed
( ~- F6 \: K) P3 X# l7 u  ask turtles [ set-car-speed ]
) m( m7 v7 z- L9 |! o/ _* O' V5 ~7 B4 g: g* R7 E
  reset-ticks
; ~" h! M" L" Q5 kend
" q) j- o* j* T4 d
6 Y7 s" _5 B& A' H" G5 G;; Initialize the global variables to appropriate values
* d/ n# u) Q$ rto setup-globals
! x* Q7 ~$ N3 S5 t- p4 N  set current-light nobody ;; just for now, since there are no lights yet6 y/ a- S( r' ~1 S7 C8 ]
  set phase 0
0 A( }  S- s6 X  set num-cars-stopped 0! k! P3 q  W5 _; y! T4 J1 w2 ^
  set grid-x-inc world-width / grid-size-x
% U) S7 T! w. [" t0 z  set grid-y-inc world-height / grid-size-y
! {; X9 B6 p  o0 N  q+ ~7 s; ^/ t8 b( N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ O* ^; `, ]2 P5 V  set acceleration 0.099* S% A/ B$ e% ~5 {$ H6 s2 d: @
end* m- Q: f& Y5 ^) }. B$ O
  S' _0 C+ @' h6 G6 r2 J! u
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,+ Y% G0 g! I9 \
;; and initialize the traffic lights to one setting
0 ]+ r# J$ w! U# A" z: rto setup-patches
- Z/ x+ O" }2 W' Z1 y* d* h  ;; initialize the patch-owned variables and color the patches to a base-color
# ^5 L: W+ _% g" Y/ z+ D  ask patches" E& F, X! {& [# ~5 Q. a2 o1 D
  [
9 |3 S8 h8 j. S  d7 f    set intersection? false; J8 Z+ {% S$ Z( R, @
    set auto? false$ s+ k- J* C4 M" {% E8 }4 L
    set green-light-up? true6 j) j* K) t9 M: @6 @( q3 Q4 [
    set my-row -1* n: f" I+ }: j- v
    set my-column -1
8 A4 E" `9 q: ~" S" s/ q3 X& f    set my-phase -1
2 S: f- K+ s, D: u8 M$ x    set pcolor brown + 3: h. P2 h$ V, ]* P8 \0 d5 r
  ]$ `7 K( O/ c" L4 m* ~4 t
, m5 v7 ~  b" R! i4 o. z% a
  ;; initialize the global variables that hold patch agentsets. A1 Q; j* d3 m1 U- p1 J. h
  set roads patches with
' ^! k" _9 J4 ~& Y2 ^. X( S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 l4 U$ k5 r! z5 C% M. m3 m% J
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 W3 H. ?0 P( x. i; O; O2 J+ y  set intersections roads with/ r9 m; B: n' _0 ~" K1 A: `; I! t) u. U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 d) A+ U0 r, D  X5 u5 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
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  ask roads [ set pcolor white ]
* I) [% F% H: d! s: ^    setup-intersections7 D8 `6 x: r* N' n
end
% V4 ^; X( l+ U3 d" }. P其中定义道路的句子,如下所示,是什么意思啊?* n% S  M+ F& O. ?$ F" q
set roads patches with
/ Q. @; G# d; x: |* p* I+ J: I. b    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- n0 C. Q! `, N: v# \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 J' ~1 f: @- I' O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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