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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。8 F5 S- L2 M3 i  n( H$ F4 }
netlogo自带的social science--traffic grid这一例子当中,/ t! J: j9 h% R9 ~/ s
globals6 \# a$ B1 g) ?( o! g
[' x2 x/ d) o) i# j( L$ w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction  I) [, u" a& P9 m2 u
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, s  N* Z; g4 U( t0 [. ?/ K" j+ I  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 x1 d1 a  s8 a1 ~                           ;; it is to accelerate or decelerate, j8 t+ r2 \3 Y% U" V: _. ?2 L2 E+ a
  phase                    ;; keeps track of the phase3 \9 c  N8 d7 e% i" W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 v2 E$ `! C1 q) N( Z. ?  current-light            ;; the currently selected light
6 _2 j& x* @' p& R6 i+ O4 f2 r
# ?/ f" G8 b, U- }. E/ [# e; _  ;; patch agentsets
5 e, t0 i( {7 Q  intersections ;; agentset containing the patches that are intersections
, ?$ H5 k3 F1 N' j, S" C1 u7 I# N' i  roads         ;; agentset containing the patches that are roads
9 G1 p6 B* T4 D* D]
' K, k- Y6 ~! H2 O& C( U4 e6 k( n+ Q* G7 I- S
turtles-own. k7 O: d' {( z$ s0 l7 v
[( C( f0 p% D4 C+ ^( }
  speed     ;; the speed of the turtle) }" W. H5 {5 ]3 I" G3 x. p8 \
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 g, j% V2 q/ l; g, d  wait-time ;; the amount of time since the last time a turtle has moved* e2 n5 Y2 n$ B6 S  q+ {2 |, Y
]
: {" k8 {5 z- x, J3 [% ~; V0 S
! |, B1 p$ u& r5 U, Xpatches-own0 T1 j2 K, l( H
[( D8 }' C& K2 Z
  intersection?   ;; true if the patch is at the intersection of two roads. q% b" `- D3 U; b! f8 A6 u/ h
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
$ R. f* ]* u0 T: z/ C                  ;; false for a non-intersection patches.
- _- W9 j) e# z- \* @  my-row          ;; the row of the intersection counting from the upper left corner of the& b) ~* J2 s% B' ?# ]5 ]! T( a
                  ;; world.  -1 for non-intersection patches.+ D0 U1 o* }6 Q2 q
  my-column       ;; the column of the intersection counting from the upper left corner of the
% O  F- s% v/ W" e% R9 C                  ;; world.  -1 for non-intersection patches.
7 X( f3 i. U8 `- \6 Q  T  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* S+ {  y. s/ s- h% \( Z& y
  auto?           ;; whether or not this intersection will switch automatically.
+ f5 l+ U0 Y: N) q  m! d+ _                  ;; false for non-intersection patches.
' J2 q7 ]0 i' o+ u! Z]+ z' x7 p/ N, J) x+ S

7 `) Q) D) p: s; b, V+ t+ y
& `/ u% z% U0 T' e1 Q6 ~;;;;;;;;;;;;;;;;;;;;;;
! s' a* d( Z  X! z/ J;; Setup Procedures ;;; `: [+ S( x7 e( X# G# C' J) B
;;;;;;;;;;;;;;;;;;;;;;/ c& U* f% _! u+ ?! R
6 Y( I; B1 {( |! R- {) W" F$ s
;; Initialize the display by giving the global and patch variables initial values.
5 \9 B6 ^( r' f2 X: h5 f3 p;; Create num-cars of turtles if there are enough road patches for one turtle to5 ?- o5 Q1 e3 H) }+ Y6 l2 G
;; be created per road patch. Set up the plots.# v: I7 `. J. R( i4 Z! N; z
to setup
3 A6 A: S1 R% c( x$ ~" C  ca
6 H1 ]9 T  f( e# z! f$ |* w  setup-globals
) w2 ?4 G) y2 r) q8 c
2 [$ d& u0 ]  S  ;; First we ask the patches to draw themselves and set up a few variables! G, \+ y% s0 V8 @: U5 L7 J# g
  setup-patches7 N( K$ c; X8 D5 b. f& q
  make-current one-of intersections
. o/ H4 u+ F; x, R/ B  label-current, H4 c# y) `% _& A( Q: ]" N! ^

: @6 ?' z' {; G/ O  set-default-shape turtles "car"
  c! H% B' ^) q2 W" S( D9 O" |3 W% M& h* |0 z6 r
  if (num-cars > count roads)
( L, ~( U7 G9 Z# O7 I7 M7 H  [' e9 D8 _9 |4 A0 m4 F9 _, a
    user-message (word "There are too many cars for the amount of "
- S7 Y! W5 M% I. d, V  U$ D- Y                       "road.  Either increase the amount of roads ", Z) y$ ?; A. q5 P6 Z1 C# }8 e
                       "by increasing the GRID-SIZE-X or "
$ d6 u! e. W0 `- `                       "GRID-SIZE-Y sliders, or decrease the "8 q7 R# P* i1 M
                       "number of cars by lowering the NUMBER slider.\n"+ I: ~/ R6 J0 J  \5 q6 A: G
                       "The setup has stopped.")8 @- ?8 o5 @4 N2 K1 e3 x; ]
    stop+ n, a( B  ?1 u& O. ]+ V
  ]- o* V# F( ^4 k
/ y+ x/ V  u" F* v7 W; \
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( n. @$ v" d7 b4 Z  crt num-cars% a5 ~9 Q% T. F& R" R7 m3 @
  [# W) \4 i, H; s1 m$ `. ]$ e. K3 l
    setup-cars
$ p: J% {7 L7 v: x& a0 h  i    set-car-color+ E! a, t$ g( U5 ~+ j3 ]% R
    record-data
7 e4 A" W4 m, ~! X* i* K  ]
+ G8 {5 T' w1 b$ z& C) c% |* i4 a' a1 y1 C  a' h. ^3 W: c) X
  ;; give the turtles an initial speed9 z" l9 S, G# s8 p2 E
  ask turtles [ set-car-speed ]
6 E8 E; e! b1 T
) Y1 m& \: @. a  reset-ticks8 a5 U, `" `  g7 f
end
, `; _5 L4 l% t( w2 X% s8 Q9 k$ @; ?; y$ e! \
;; Initialize the global variables to appropriate values
2 h8 J/ X+ T* }6 ?  b) z3 {to setup-globals
  W4 I7 \! }' [/ d) V  set current-light nobody ;; just for now, since there are no lights yet9 g5 \/ m, Z* G1 ?* z; `" s
  set phase 07 p7 z! t& m+ w. _9 R
  set num-cars-stopped 0( U, b7 P% ]$ z" h3 {2 x! }/ D/ o
  set grid-x-inc world-width / grid-size-x
5 A% B) N. v! L3 c9 q& F' U  set grid-y-inc world-height / grid-size-y# b4 ]4 n( r5 Z$ h  }# S/ J8 ]
( V. }2 K! u6 ^
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- v6 \) c  O+ T, A
  set acceleration 0.099* m/ I+ i" m( C1 u
end
/ Z, U9 W, p1 X+ i& N; e4 ]8 |% w$ q& v
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' H; q- P- g" }+ `6 A# M: K
;; and initialize the traffic lights to one setting7 k/ C0 J0 M6 \) C& W
to setup-patches
6 X; E$ n5 L5 [2 n  ;; initialize the patch-owned variables and color the patches to a base-color
, M) s# p- K, C8 c7 K  ask patches
: z! p! k0 _; K/ o% r4 I7 t1 v& m  [! A$ M; q' c; {  _
    set intersection? false
% f6 H. R6 q/ H    set auto? false, o9 e) H0 n+ D4 V6 I1 l
    set green-light-up? true
! g  ^$ h# s7 F0 Y+ E' j. q/ ]    set my-row -1
* r: p# ~0 N; Q7 K! `    set my-column -1
7 x- z! C( L( C. W  j6 S* Y5 P2 {$ q    set my-phase -1
) ?; g) m) p; e* l( {' J6 B    set pcolor brown + 3
2 f$ O( C! F' u/ P/ I' D7 m1 P2 ~  ]
* i+ b- Y# W4 }% r3 e# D7 l3 ?/ [, R7 s- Z7 q# m. `
  ;; initialize the global variables that hold patch agentsets4 G. M( t, K3 J. ^* s  u
  set roads patches with
! N/ t8 O& ~* c5 z& L& Z: ~* x$ ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% j, Z$ m' M7 b! w; K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]) {/ ^' |3 g  P  w2 G3 `2 Q, k
  set intersections roads with2 d' e8 z* J6 g+ |% x6 }: P& w+ v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& W# P' V. g* O9 g( t5 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 U1 `! g0 [# v5 A

$ Y; m/ B; J" |  X  ask roads [ set pcolor white ]; d. Z" j% \" i2 g/ U' G
    setup-intersections8 \( A* F/ _( r1 C* _
end7 w1 }7 ^5 q& C  N' T5 ~0 _
其中定义道路的句子,如下所示,是什么意思啊?! ]% K7 l# F/ Z; M: B5 {9 l; x
set roads patches with
  \! W, E4 ~, F8 s3 ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 K0 t7 D" X9 Z. v8 z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" M2 r! J* g! D* i; r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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