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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。( L5 L, A- K% b
netlogo自带的social science--traffic grid这一例子当中,
7 s+ [* q) x' L5 V/ T" jglobals6 `0 {! {2 E& p/ @- G7 ?4 [; v
[2 y: F6 Q8 S) o
  grid-x-inc               ;; the amount of patches in between two roads in the x direction  c0 O* m+ u) V, u2 Y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 U  c) B" X* b1 m1 f' F  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  G  A& m  V# b/ i' D, R7 }                           ;; it is to accelerate or decelerate. m, @7 O  s* W& G2 Z( W" z" Z+ P
  phase                    ;; keeps track of the phase
4 ?! M/ I% x1 b; D$ Q  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure2 c% e' [4 f: D
  current-light            ;; the currently selected light( t! u; }. Q& d
2 l0 E& U0 \: L) |7 D/ y( ?
  ;; patch agentsets/ _1 O9 z+ e* _+ V" I% f2 \) z
  intersections ;; agentset containing the patches that are intersections
, B8 m$ D- |& b  roads         ;; agentset containing the patches that are roads
# T8 j/ x& y/ I4 Q9 k! V2 ~]
7 `* L# Z; l- t. e/ J: _- ~+ _  h  q3 c3 J2 B) O2 D+ ]2 H
turtles-own
' h& h. D  A8 J[3 W7 F1 O5 E7 l& w5 [6 I' D
  speed     ;; the speed of the turtle1 F, m2 K' K- M# b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! w- k% Z9 T6 V0 Q
  wait-time ;; the amount of time since the last time a turtle has moved. B, I+ [6 m3 e8 e9 n4 ^
]; f, G* Y0 P# D+ y
+ n  b1 ^. ^- ]* g7 `. E* D1 y
patches-own
' f1 Y0 p# Z5 f[
4 ^9 \2 J8 \! Y& Q* I( l* _, j  intersection?   ;; true if the patch is at the intersection of two roads& o) K6 U6 ?$ ]" T* _" u3 A7 W
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 S8 v( t# i/ q4 D# |0 q                  ;; false for a non-intersection patches.
2 p! O7 }+ P& B- M  z9 N  my-row          ;; the row of the intersection counting from the upper left corner of the
# Q2 h& C- d; d                  ;; world.  -1 for non-intersection patches.
; O6 y2 N+ ~; Y) M  my-column       ;; the column of the intersection counting from the upper left corner of the
! |7 L, X3 v& s, |; ^                  ;; world.  -1 for non-intersection patches.! u7 E4 k4 f6 W5 F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." v7 j% k7 j+ y) U: b0 j
  auto?           ;; whether or not this intersection will switch automatically.
( {2 j! o' n' v5 }9 P                  ;; false for non-intersection patches.4 t0 w9 J' @: ~% V, V, k
]
$ x8 s6 {) t" r& m# g
3 M* r3 s- b/ G8 C6 a$ E9 ^4 Y
+ p, z! |% z) `7 L* n;;;;;;;;;;;;;;;;;;;;;;; m" e+ o4 G+ V; h+ C- F/ e1 s
;; Setup Procedures ;;
' P2 S! m7 N( ]" v9 n;;;;;;;;;;;;;;;;;;;;;;( ~& ]5 a, K+ f4 |# ?' V

. a! N) m; q. P  {' f* F; H* B: E;; Initialize the display by giving the global and patch variables initial values.
. a: I) e( c% S' v* F;; Create num-cars of turtles if there are enough road patches for one turtle to. F; B) |/ z- b- Y/ Y
;; be created per road patch. Set up the plots.7 J$ R1 j* j, A1 b& N) v
to setup; g% t1 ]0 A  {
  ca
$ e4 h- K+ k* `/ _$ F- `  }$ ?  setup-globals. {; \" r" j: D5 D
& @# o* L$ }6 |8 C9 G* y" _& `
  ;; First we ask the patches to draw themselves and set up a few variables
6 A0 }  B/ ^& Q. l/ J% x+ i1 z  setup-patches6 D5 Y  m: b2 o% K$ A
  make-current one-of intersections
, d% U9 |4 d* G7 [3 i" R/ ^  label-current
. ?3 N  w% R1 z/ n7 j9 h2 ^! x" N3 B
  set-default-shape turtles "car". T5 S2 A. Q( `3 E4 g

1 H* h2 w* I; k. O$ i( V( Q" \/ Y  if (num-cars > count roads)
' _7 i8 r6 z4 i7 ]! [1 _) M: r- c! M  [  Q4 i' C# `2 S. Y) Z
    user-message (word "There are too many cars for the amount of ") J, s8 ?! g, B: q( \
                       "road.  Either increase the amount of roads "
4 b' X7 W! ^6 P+ A- y7 A1 `                       "by increasing the GRID-SIZE-X or "
1 V/ D/ V% z( K                       "GRID-SIZE-Y sliders, or decrease the "
9 a0 [( U9 c2 [. {& h$ ^                       "number of cars by lowering the NUMBER slider.\n". i" A9 Y, o; @$ Q" h
                       "The setup has stopped.")+ M: r- U. z1 W# E  F$ U# N: X7 i
    stop$ B! d, M0 n- c9 `; \* s, }
  ]
4 V; [. `' f5 _; M! S$ g- i7 h9 b3 R: J6 `0 i$ e7 A: i7 D, s5 x
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, R: i' J: y# g( o- j" }  crt num-cars
- X2 V5 q- u' v( O; H( N  [
7 x4 s, ?5 L! S, ^! C6 @' ?    setup-cars  B$ ?, K' J" f7 @; }
    set-car-color) n- R& U' _  x  f( C  I, z
    record-data% k* Z* y( N5 E. p
  ]
5 o" J7 i3 o% V: t. I& f
9 b  [# {$ V$ ?+ X1 ]* t3 v( ]0 s3 x  ;; give the turtles an initial speed, ?; C" ]) W# A+ _3 ~0 [. \
  ask turtles [ set-car-speed ]; s/ y$ u/ H/ T% g8 T: N: O
3 O8 `9 S! ~' w2 l, x9 F$ R1 E. v( \
  reset-ticks
) E+ T  @+ n$ e* B* Uend! k: J6 y! O; w

- [; p- n& d1 j* _' `;; Initialize the global variables to appropriate values& h5 A3 }. J( e3 }- B% V
to setup-globals
  @* T* f: W: x* i  set current-light nobody ;; just for now, since there are no lights yet
# ^* a7 e9 I0 }5 c+ Q  set phase 0% T; B; h9 R, G/ T9 T5 X
  set num-cars-stopped 0% \9 o; X* o; ]) D. R: ^; P
  set grid-x-inc world-width / grid-size-x! T7 z* Q5 E: X1 `) j" B- T
  set grid-y-inc world-height / grid-size-y5 T: X- F, y7 g/ ]
6 E) E% n7 T. ^
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, ^9 q0 }9 C, Y/ I' e
  set acceleration 0.0997 s0 ]- b+ A2 @/ d8 T" G  i
end; ^" H$ [& H( J& S6 Y, l+ k! v; `. M
1 ]6 T/ Y$ B! n9 s0 T
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
# ]% L7 Z/ m& ]: w;; and initialize the traffic lights to one setting
" y' I7 K0 k% \+ O0 y$ z+ Zto setup-patches' `8 N0 S* i: `- B) z
  ;; initialize the patch-owned variables and color the patches to a base-color) M3 V1 `' p8 w6 C: H
  ask patches+ `7 f; v: d3 }; c. u. {. u) s! m
  [/ k; l+ @  b* c1 g: F
    set intersection? false
& V- P, S; x1 t    set auto? false
$ b- S+ e; K" L1 D4 e1 |/ W7 N    set green-light-up? true
$ m  d* i6 X# z/ h. W    set my-row -10 M# |% |2 X% M9 x. [
    set my-column -1& `4 _9 q0 M/ K; z/ U1 H+ @& T
    set my-phase -1
6 e/ A$ H% f& L# B$ ~: W  Z. r$ R    set pcolor brown + 3
7 q2 |4 b+ o" J$ p  ]) W) a; K4 z: i8 M% H

" }7 ~3 s3 j- f$ W9 n  ;; initialize the global variables that hold patch agentsets
0 v$ N4 }- u2 g7 P  i/ g$ ]  set roads patches with
& t+ D( B: U6 i- U) n$ H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" K; P2 }0 {. E5 f/ Q* T5 K) D5 E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- e4 v/ f( q, R% x0 S
  set intersections roads with- R8 h: o4 U" C% i# U5 q' B8 d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and% q0 y( v$ B" h# Y3 A: ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 V' J5 _0 D2 Q3 ]1 |# v5 N  z1 d3 f

" r6 j& h. [! }' G  ask roads [ set pcolor white ]0 x* t) |- j6 m; I! w6 {" G
    setup-intersections
1 u* [! I8 w8 v& ^  Y. gend4 I% o# ~0 I6 Y/ U. |' g
其中定义道路的句子,如下所示,是什么意思啊?! H2 f8 x& r8 g1 o" L/ h! l8 f$ [
set roads patches with% v' Y) M  X) D4 ?% e" P* D
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 ~- R% D; d% a% |/ _7 k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
- F! `* w; J. B% m5 s! 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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