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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。  H8 c3 P# P8 {6 T: T- b2 o! I* G
netlogo自带的social science--traffic grid这一例子当中,
$ f# x9 ]; J. x- ^) bglobals
/ p: a: Y4 o( G/ e' h# E' ^[
7 ~$ V! K+ l3 f3 C$ t) |  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 |& z1 s  j$ N5 x8 g; ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction( o( g' n) Q- }6 n/ X7 N
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& r* @' Y+ M* r7 l: d1 N                           ;; it is to accelerate or decelerate' P1 O. U; G. J6 E2 _) F
  phase                    ;; keeps track of the phase
" S; [( N  C& z  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure! J' Y+ S3 Q' l$ Z2 K# q1 I
  current-light            ;; the currently selected light
, ]# D5 z1 J. n0 C2 W
/ G+ P) i6 u) N- b+ I! `  ;; patch agentsets" h! z6 m# d, B4 M1 @1 R. ]
  intersections ;; agentset containing the patches that are intersections/ }+ [2 z  E- o3 d1 p& x
  roads         ;; agentset containing the patches that are roads
" D7 n7 m( y0 U- ]1 ~" c]
4 T9 @- V1 h1 O, V1 u6 U  e, |3 g! B5 t# {
turtles-own! C- `6 ?! n, ^. ~9 L4 M
[
: C7 E3 N" k1 x8 L3 L6 r1 O5 v  speed     ;; the speed of the turtle$ G4 {; d9 O5 `/ v# p" b- W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; r/ z" c/ E/ S" c
  wait-time ;; the amount of time since the last time a turtle has moved
* ?$ v: p" Z! []; q6 N* D* v- m8 Q
# R/ H# V8 J/ e" {
patches-own7 V# j* n. ^. l: ]  B/ b* J, q
[' p- j( O4 v) c
  intersection?   ;; true if the patch is at the intersection of two roads. P! o3 u, f; I; t, |
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" |& P8 r5 M; E* W0 W                  ;; false for a non-intersection patches.
/ R! `: D( d& l1 D; F  my-row          ;; the row of the intersection counting from the upper left corner of the! P7 g  W5 u5 J! a7 |
                  ;; world.  -1 for non-intersection patches.8 V& Z. F8 b* @; O; _, P/ ~
  my-column       ;; the column of the intersection counting from the upper left corner of the
6 m- P. t2 O0 J: i! v( k                  ;; world.  -1 for non-intersection patches.
# j+ t: c, x8 I) p( K5 u  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. P1 |) w6 J- ?8 L  auto?           ;; whether or not this intersection will switch automatically.
& x! R' d6 |: K0 \                  ;; false for non-intersection patches.5 U# Q+ |% O5 c$ |
]/ {$ l1 o3 Q" i7 R; B1 I: W8 s: R( z
( A8 G) S& J6 D1 o1 v2 j0 @
8 o: P' r% ]; l
;;;;;;;;;;;;;;;;;;;;;;1 @6 l* |- ]& ~5 m; i
;; Setup Procedures ;;
' Y& _: O, u/ {9 @  J/ i# q% U& n;;;;;;;;;;;;;;;;;;;;;;
' ?: ]) t; y6 I5 j: W& X0 y3 E
' V7 C" N* V- e' v8 H;; Initialize the display by giving the global and patch variables initial values.8 U/ z3 V# A7 k2 R2 M3 }
;; Create num-cars of turtles if there are enough road patches for one turtle to/ O2 S- H- g  A# J' p9 o
;; be created per road patch. Set up the plots.
* F6 K/ o& u* M% rto setup
# U+ h$ N0 l9 W9 O  ca
2 ~' o# }4 d; B  setup-globals( b, ^! ^/ r' l7 a

$ r3 U. q2 R9 j9 p  ;; First we ask the patches to draw themselves and set up a few variables
  e5 M# z9 y0 R; M0 U% _  setup-patches% L4 ~+ z9 U, M$ ^) o- }5 z
  make-current one-of intersections
8 z; \3 V6 Y3 d5 N9 w/ H  label-current
. X) }+ Q( {& o+ Y% u6 Z
! z( ]: O, k. X; T7 ^4 M  set-default-shape turtles "car"
. Q0 P! l) N, ]# D2 H" z- O) k9 y* I( B$ ?8 o/ Q: G6 Q: ~
  if (num-cars > count roads)' n0 ^! C* m) B$ n- Z2 V
  [
4 d5 r  v, u4 |, @# K7 }    user-message (word "There are too many cars for the amount of "
3 ~3 c# o$ g7 {& u, y) Q% C" P# d                       "road.  Either increase the amount of roads "0 r* N' P5 d9 ~+ X8 X
                       "by increasing the GRID-SIZE-X or "$ V9 g. i- N# O8 P* P0 W
                       "GRID-SIZE-Y sliders, or decrease the "; n% @) t, V- f4 M
                       "number of cars by lowering the NUMBER slider.\n"* p" V1 W" O. i2 h
                       "The setup has stopped.")
) ]8 @& d% o- z% @0 M. A" E    stop
# H& y9 G+ I( j3 ?, z' D* u' v  ]
! B1 O$ f* }1 A! _' L* O
. ]# u, v% L2 }6 y* ~% j( k' ^. U  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 K) @! Z& V  L& @  crt num-cars
4 W% ~, D3 h5 G8 }  [* R# U  \3 ?" ]
    setup-cars
  d/ W0 `# ]* b  S' R/ j: J    set-car-color
2 D0 ]9 X, L. |# j; v    record-data
% R8 ~2 ]9 e' p. ?; d  ]5 D+ G' w4 k& H

% u; |7 w# y. V6 [% L5 o  @  ;; give the turtles an initial speed
# J3 ]! h4 n7 x6 n4 U6 \  ask turtles [ set-car-speed ]
4 k) ]4 u6 s/ f4 {4 d) E5 y7 E3 R7 S; H
  reset-ticks/ U% c! C; K, `- C+ O6 A1 z/ u9 G6 }
end& p& V2 l0 V3 c" H) H: P, N* d: z
) k6 H2 k  n! v4 E  u8 T1 Z
;; Initialize the global variables to appropriate values
$ \! b' {9 J* P/ W# nto setup-globals
- ~; ~) H: n9 _/ s  set current-light nobody ;; just for now, since there are no lights yet
; U" E3 U; R% P2 r% G# y) `  set phase 0
. p; M! t% I0 ^8 S8 L8 [  set num-cars-stopped 0  l! u9 D" [/ _! n& c$ ~
  set grid-x-inc world-width / grid-size-x- o; Z+ I# V3 H5 X2 O
  set grid-y-inc world-height / grid-size-y
5 t, a3 [5 W( Z9 v' p; H% y9 }- U9 R/ S& y4 I* ~7 g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. q! u% W* }) \  ~  set acceleration 0.099' n1 P$ W% @' _1 O4 f3 G0 @
end( i' g2 z% w1 U7 c2 ?

& @8 b& A# h( J7 _" K;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) v' H. o% ?3 B, V& s. w
;; and initialize the traffic lights to one setting  k3 D( {" P8 Y* ^* p
to setup-patches
- x7 W% s0 x( W. X9 [& _  ;; initialize the patch-owned variables and color the patches to a base-color
- S4 F9 e4 L7 l% X6 P2 {5 f  ask patches
# q8 w7 S7 y% N4 F9 i9 H! j# u8 C  [
5 a: R4 N  ^" _- g, O) F* k" d    set intersection? false; a- I- ~# t1 _- _
    set auto? false7 J. _, z) G5 Z( _* V
    set green-light-up? true4 z2 u/ W: M0 f+ ~1 @& m" X' e
    set my-row -16 g  |- x4 E7 k6 B& ?( o  u: h
    set my-column -16 J) U& r0 T5 r+ A6 p9 }$ G
    set my-phase -1
- `5 _9 @! J5 q" R- o3 ~    set pcolor brown + 3) O  c) K; M$ P* B
  ]
% i% P4 p9 P# @- a3 i7 t5 C2 u
: c7 @7 Z* {$ q# t& C4 W+ z: c5 ?; w  ;; initialize the global variables that hold patch agentsets& s8 q, F% e! q' s
  set roads patches with: |% t7 F* ^) {7 {  j1 @: c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 o, S+ k1 ~! I0 ]1 O8 `: q# U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 R0 o# n6 c8 O! w- t3 w
  set intersections roads with
1 Q- i$ h, z, k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  `3 h/ h% ~0 m9 I& s
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) _/ U" J8 b0 k# g  P5 {/ z  t/ T( D) D. z* B, q* }
  ask roads [ set pcolor white ]
7 H+ [9 r8 d: c. @7 O8 X+ X! J    setup-intersections
, d# P8 l+ m* uend
2 y* w! R, k0 q8 y) E其中定义道路的句子,如下所示,是什么意思啊?
( C7 U6 @: H; K6 g. k+ n" ?' m set roads patches with1 c$ A$ D: ^# v7 a! }( u2 b( u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 j- V( H8 m2 A; T, K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* y0 r5 u* }0 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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