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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。
3 c$ k- g6 G0 }' g1 i5 m8 @netlogo自带的social science--traffic grid这一例子当中,) n2 P# h" G1 J  m
globals9 E7 }9 i& ?$ t! B4 ?& H( m
[# K" H  F) R4 Q- t5 S1 c- e
  grid-x-inc               ;; the amount of patches in between two roads in the x direction  P& L0 s% ?+ s; ~7 S
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' V- q  ?4 B2 V4 K
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 o9 b& S8 H0 c0 T0 \" w3 P
                           ;; it is to accelerate or decelerate0 U! w, Q, E! Q/ b) O& ~3 d; |! v$ s' _
  phase                    ;; keeps track of the phase: J; h( |9 w: Q! g
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, S0 U! Z2 J8 x0 r
  current-light            ;; the currently selected light
9 W! G1 I0 p& C3 v" c# G
$ G, P/ u0 k- b- I2 n  ;; patch agentsets
% Z6 n8 `0 ]+ R1 e6 ^4 U  intersections ;; agentset containing the patches that are intersections* E* y4 H, B5 a) c
  roads         ;; agentset containing the patches that are roads9 R$ M4 k+ f2 }1 ?
]) U3 j8 ], H# V# r2 \, u2 p' Z
! _7 y2 L/ @" H0 _( K
turtles-own
% t) o6 r! t3 R1 V* I  n% c6 B/ ?4 P[0 ?- a9 Z  o+ x$ E. L
  speed     ;; the speed of the turtle) y! e# p4 E7 p& K5 A6 ]
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& h; ^5 M& p% Y0 b6 l/ D
  wait-time ;; the amount of time since the last time a turtle has moved, k7 T+ b# ~2 f: n9 X
]
3 U$ |: o4 ?  H* }: X2 z& k8 N3 i6 e( s# ~
. M; t1 D2 Z$ _' I: |( g5 {# Jpatches-own
6 @* |5 a* p$ ~( X[* n$ W# @7 g! U- \8 `. p
  intersection?   ;; true if the patch is at the intersection of two roads
) d6 E! }8 Z8 }- Z4 d  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  E/ e0 s7 q) |6 |                  ;; false for a non-intersection patches.6 ^: i( U* Y- Q
  my-row          ;; the row of the intersection counting from the upper left corner of the
* O: ^3 k, h- Q. ?$ ?/ D: K4 E" P  k                  ;; world.  -1 for non-intersection patches.) G- j) B- e/ g4 }/ M' {
  my-column       ;; the column of the intersection counting from the upper left corner of the" v/ ]( c+ L" M1 X$ t% W
                  ;; world.  -1 for non-intersection patches.
+ {" }7 d* C# C8 |+ D  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 a2 [5 l$ o( L" p
  auto?           ;; whether or not this intersection will switch automatically.1 }6 k, d' y6 a7 X* O8 O
                  ;; false for non-intersection patches.8 a( l# {7 v* y1 n, K" n& x" Z9 k
]
- i5 k& C: {/ [  @7 {$ H, t7 O% D# j3 N, K4 _3 f: N8 M3 b
# r2 u4 Z; q/ O
;;;;;;;;;;;;;;;;;;;;;;' o: x3 S6 B0 ^) ~3 f: U( t0 O; z
;; Setup Procedures ;;
  u# Z; Z7 o2 a8 j0 E4 @;;;;;;;;;;;;;;;;;;;;;;
" @) T1 `  `6 ^6 K: r( z
2 ]) \  V+ F# e+ n* w;; Initialize the display by giving the global and patch variables initial values./ _9 Q" i/ I1 _: W: D
;; Create num-cars of turtles if there are enough road patches for one turtle to3 B& U, Q  X7 \, o3 D( v
;; be created per road patch. Set up the plots.  X" D8 v" W: G, Y6 [
to setup
7 q2 d% p3 V0 Z, M  ca) l) S2 U+ s$ m* U7 H% H0 X/ }
  setup-globals
+ H, X5 z- N" \( M& `# l4 w8 @: I+ r; q5 n
  ;; First we ask the patches to draw themselves and set up a few variables
1 @" k( t( }# |/ U1 @. u  setup-patches
& c% B  i. l8 K; d% i& ^, A  make-current one-of intersections
0 q. U; Q# p1 u, C7 \  label-current3 _6 \8 H! M3 ]- w5 k" a  \

* |  G0 n; f& v  G3 {  set-default-shape turtles "car"
& G3 U8 ?% l, I5 Z6 J' M, ]; C& d% _1 N8 H9 e- \* g  H
  if (num-cars > count roads)' Z6 j& B9 T+ h+ w0 N- s1 f& S
  [0 D4 a* H1 d+ M& H% R& P" r
    user-message (word "There are too many cars for the amount of "* R( J$ _/ e. k% Q
                       "road.  Either increase the amount of roads "7 S. V* N5 a5 h1 W% g4 q0 x
                       "by increasing the GRID-SIZE-X or "5 Z7 H: C* V$ T
                       "GRID-SIZE-Y sliders, or decrease the "
. H( L6 A( s! l+ j; b0 X. v                       "number of cars by lowering the NUMBER slider.\n"0 N% z5 c# H; I' K5 J! w
                       "The setup has stopped.")
3 o. V2 m6 Y+ Y& A% D" \    stop2 p5 N* U: E1 _3 H' x
  ]; Z3 G/ w0 X' R2 `0 X

6 d* {8 d! S( v* y7 ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color5 w4 G5 L+ \. c9 O& \2 d
  crt num-cars
3 G! w# y' S) _1 M5 y  [
; t# K6 a% u0 i: _    setup-cars+ S+ z" h: j# Y) _8 F
    set-car-color$ n1 n9 L3 P! D; g+ [
    record-data- ~# X3 {) P- \
  ]
' m2 ^  P* \7 y+ R
# Q) B$ T( @  J9 z  ;; give the turtles an initial speed. g* k- q- n% i( ?5 @
  ask turtles [ set-car-speed ]9 B+ J$ K1 b5 i0 |/ W1 f

2 e* K( H6 K+ r1 `  reset-ticks" M) t  m# H- p3 J3 o# f, f6 x
end* Z5 i8 m0 [1 V: }7 W  R

9 [' l- b; N- t0 P9 i;; Initialize the global variables to appropriate values
* b: K/ [- ], H2 G& ~5 `2 hto setup-globals7 t5 G: y2 d9 G( Y- q5 s
  set current-light nobody ;; just for now, since there are no lights yet) G% `5 x& j  V
  set phase 0
' g9 L+ r2 l7 q( B, e5 c  set num-cars-stopped 0/ p- Q& y. N6 _6 K
  set grid-x-inc world-width / grid-size-x
" j% _( G. V: V! H" z" ?  set grid-y-inc world-height / grid-size-y
( ^* t. N+ W* V" W8 @/ {
4 A" A( H1 H" l* u. C. o  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" O8 b; N2 i8 e; R# F1 q0 ^  set acceleration 0.099
, N# L% ~* l' z" s: H- t  T" Eend
- Z) ~) o3 @% B# U# e9 S6 x7 p
+ k  d& T/ u% S/ B! `;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 _. N2 Q! P% t1 U% X;; and initialize the traffic lights to one setting- D1 J" ?* }& m) L8 P
to setup-patches8 h1 b' ~' y/ C  |$ E; g
  ;; initialize the patch-owned variables and color the patches to a base-color! r8 L5 Z: z! A( }  u; r
  ask patches
5 l/ V% I/ q1 M* s% ]& b1 Y+ x  [) M, F6 A. B  Y0 }, R. R
    set intersection? false
( _" r6 n$ d6 ^    set auto? false  q) \( M/ K* `0 T* c
    set green-light-up? true' S  L; |& V! t8 A% f, T* r1 G6 D
    set my-row -14 `2 p* Q( g) _% F, G" l+ \
    set my-column -1$ |5 Q; m+ p1 _$ J( r# E
    set my-phase -17 d( J* s' C% Z( R3 H$ n1 l
    set pcolor brown + 3
% N+ \9 f+ z  i' k1 C% o  ]
8 G8 |5 `" c- {4 Q9 n7 o" y0 I+ b+ N* H$ A) ], g& d9 z1 c. J8 F% ^
  ;; initialize the global variables that hold patch agentsets/ O* v$ c. Q7 C) L* I/ Z* s( p
  set roads patches with" i) w# Y: u: A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 Z0 ?( Z1 V% f# }5 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* Q7 V. T3 S- `  set intersections roads with
4 t- L: ^7 J5 O! d" O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 ]7 y, }+ m% r. ]; u/ S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 |2 P( t. \% m8 o" _% t
- Y2 A) m' J  j& D3 l* |  ask roads [ set pcolor white ]
! m/ |: l; R& W) n$ u' v    setup-intersections, r- M- Y3 F( J; }3 v
end: O6 f3 X% S8 _7 h3 |, [
其中定义道路的句子,如下所示,是什么意思啊?, p6 J5 z+ C/ c7 h' h( p
set roads patches with
4 }% b3 i" I  j) k) S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& ^+ y. w: D# h. j& A9 |  F8 _' {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* c* _; A6 s1 V2 w% S( L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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