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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。' J+ d3 ?6 \% l8 v* _7 V
netlogo自带的social science--traffic grid这一例子当中,
; u7 B0 L) E9 |& G6 W- o( ~- Kglobals
( ?2 V* B0 `$ C* `[$ n/ X! p$ W9 N' f, {
  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ F7 K9 k) A" H8 L
  grid-y-inc               ;; the amount of patches in between two roads in the y direction1 c% B4 O) u8 K2 f- ?2 Y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 g4 y; H& v1 L) H8 F' D7 g
                           ;; it is to accelerate or decelerate
" |; ?1 r5 a- ?  h8 Z' |  phase                    ;; keeps track of the phase  m* E( r% U7 T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 F& A( D2 y. u6 T4 f+ d3 E  current-light            ;; the currently selected light
8 i& Z2 o; {3 x. E8 k1 U- p+ [1 k! o5 b8 ?1 F+ X# z+ X+ [/ F
  ;; patch agentsets+ S" C/ Z8 i! M
  intersections ;; agentset containing the patches that are intersections
. M( j' v- i- Y7 K5 U8 ]$ T  roads         ;; agentset containing the patches that are roads' z; R- Q# P! v$ ]+ r
]
& l9 k( a1 G3 v* F; ^( k& X9 b
turtles-own% M6 f( ~# E0 l, b- g& b. D! K- A
[
+ l  n* ?0 F8 e, b, g4 Y$ t) h  speed     ;; the speed of the turtle
' t5 _  c( m1 R$ d  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( R8 ^) L$ J+ s0 m+ I! t0 \0 G
  wait-time ;; the amount of time since the last time a turtle has moved
. j% N; V/ V/ Q% N]
; |/ N5 a7 w8 K* Q* \/ S# u. o4 B* B% W6 w) J: |) r
patches-own% T# I' n  F, Z- E! j) J0 B0 s% {
[
; r7 u6 B! _  ]+ E" G  intersection?   ;; true if the patch is at the intersection of two roads
9 H% J/ _+ _$ y: q2 V9 `, R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 j8 U  n- a! c+ ?  W                  ;; false for a non-intersection patches.! w. P/ H2 ~0 `6 }
  my-row          ;; the row of the intersection counting from the upper left corner of the
( \2 j3 b4 K7 G" ?                  ;; world.  -1 for non-intersection patches.# O( \! r; n* V5 q2 C8 J8 i) f
  my-column       ;; the column of the intersection counting from the upper left corner of the) i; O2 n8 S* y8 s$ B7 C
                  ;; world.  -1 for non-intersection patches.
1 t4 c( p$ B, R, t+ X+ @  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches./ ]0 ^: O# B) V' l$ m; d
  auto?           ;; whether or not this intersection will switch automatically.0 v) ^! x8 l4 i) Q) [& j% S& k& P
                  ;; false for non-intersection patches.; [4 Y: p/ s% t2 Z- A# T  A
]1 k2 k  v; Q% p8 n9 `5 F7 [

1 p# M6 m. ~  d; [* @: B6 ^( k5 y
;;;;;;;;;;;;;;;;;;;;;;
) c! T5 ^2 A) L3 F) H; N5 p;; Setup Procedures ;;, W' s- ~& |" l) Z
;;;;;;;;;;;;;;;;;;;;;;
. O6 q: }: T% A; c) H8 i: g2 C, T/ C& g
;; Initialize the display by giving the global and patch variables initial values.. e7 `; J6 L; e1 f- E/ X
;; Create num-cars of turtles if there are enough road patches for one turtle to* u: c. c% e# W( A; X7 ]5 x
;; be created per road patch. Set up the plots." U' Z% A$ t: `" N$ F
to setup
: S) j- g( e) b4 e  ca. ?. m$ k2 u. V6 a1 q
  setup-globals" V. H. w$ q0 g* ?
7 ~& X7 P$ M. i3 A! n. O' @8 j$ f
  ;; First we ask the patches to draw themselves and set up a few variables1 g% {; C) ^( _4 d6 V5 B- Y; x
  setup-patches/ h* D! |9 o! t+ _. I2 d$ |8 w
  make-current one-of intersections; L  ~7 O; W) b
  label-current
, M4 [8 i; e5 f( b3 O& S+ Y7 D5 ~$ r7 J6 g2 b- B& b
  set-default-shape turtles "car"% U9 i5 X2 W* m; d! k- A
4 _* m) s: g. U3 s9 r+ z2 b4 u: g' l
  if (num-cars > count roads)
6 [3 B0 w% w1 m! y6 {* p( z  [
( p2 J, p1 Q3 D3 a    user-message (word "There are too many cars for the amount of "% E+ }' k+ @0 O$ t! g
                       "road.  Either increase the amount of roads "
0 G/ o1 }# }" C' F                       "by increasing the GRID-SIZE-X or ". I1 C8 X7 I4 T# @& Z# }* X
                       "GRID-SIZE-Y sliders, or decrease the "
; l* [, F3 ^& }' ~& C                       "number of cars by lowering the NUMBER slider.\n"' Q+ ~$ [- u. x; {
                       "The setup has stopped.")
0 q& O6 D1 Z  W( e$ E6 k7 S5 h( ^    stop% `, O! X9 H, H2 S8 ?8 O  D
  ]" f, O9 E# y4 ], `3 i. \# H! }
9 f& a9 v' D0 \4 r1 y0 y" s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 r) T. F( ~2 R- G: O
  crt num-cars
7 I+ [& `+ W7 C  [
# i- Y6 j: p. H1 G' t4 g; V) e  `/ \    setup-cars
9 Z9 h; c) ~8 Q* t# F/ J. }5 \    set-car-color
/ R# X2 Y) Z/ x' G1 g" D  n    record-data* b( j% Z) M$ O0 v' z* a
  ]8 O9 _; X! Z' T

4 s5 v0 c& u6 u; w% N, d/ k  ;; give the turtles an initial speed, K! v. ]$ o$ X9 u3 C- Q7 V
  ask turtles [ set-car-speed ]
7 n9 l% A; N3 P" d: l) m9 p4 A/ h5 t- @9 H4 C3 Z& ^
  reset-ticks! z9 B. L4 F/ C( c/ F
end
3 u5 A8 H( f$ N5 e' \; g8 Q# J& H
5 r5 [5 _6 m. w0 f3 H;; Initialize the global variables to appropriate values1 D8 b  ~) H$ S, t! y8 S, D
to setup-globals
9 y5 ^* ]8 t. q6 G/ ?  set current-light nobody ;; just for now, since there are no lights yet
0 Y" i- U5 f- [/ {+ V( B% R5 L  set phase 07 r% X# ~8 o, W
  set num-cars-stopped 0( ?8 v) y+ H& ^4 c* B+ n
  set grid-x-inc world-width / grid-size-x3 Q, U2 s0 k# K& ?& p" V5 X
  set grid-y-inc world-height / grid-size-y
' s- Z2 F$ ?) J8 X/ \& K
0 b$ x" J* x5 M/ F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  e. _9 k# n  x9 s  x3 }
  set acceleration 0.099- R7 g3 P) _$ n  n. N; }
end7 s4 V& {/ Q- K* S! L
7 S6 n  a/ y* |0 `
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
: H+ l( j! |. p5 S: T% [, y! ^; A;; and initialize the traffic lights to one setting
! r- Y; |$ m" g% p8 @to setup-patches& o$ v  v$ m) n/ p% A
  ;; initialize the patch-owned variables and color the patches to a base-color
4 ]: B3 }: v  e2 w6 e6 e  ask patches! `1 A( e. A& g# o5 @: a# P
  [
& Y/ `* L, S4 R2 O' x    set intersection? false
6 O% X9 j  W" i+ i- v5 {    set auto? false
. T' ^" ]* O8 D# m    set green-light-up? true( L+ I* v- O# M( Z7 p
    set my-row -1% U' u* @9 B6 W: o
    set my-column -1
' y7 w0 F! _* G2 U7 N    set my-phase -1
" A, K# N, B3 B7 l6 V  Y; O! V    set pcolor brown + 35 k$ J3 h8 G1 d" T# v( }
  ]( o& C. f6 M$ T/ ?) C

- d! c; e' w" ]$ o* y  ;; initialize the global variables that hold patch agentsets
' ^9 J9 _* n2 ^: j$ c6 V4 M6 Z  set roads patches with
: X3 F5 Y9 t) v' f( v" l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. y  m  l$ ]$ [# @% c+ u; x+ g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( A9 X' M2 Y0 M+ ^  set intersections roads with
$ H2 _# p1 \3 G: a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 g% s; B5 w. R( L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 u! Q- h4 ?4 L1 J1 J1 S3 h* I2 A

: H$ A0 T% g9 H' p. f1 v8 P) C  ask roads [ set pcolor white ]
2 v+ s3 e0 W$ }$ C- A    setup-intersections
4 i+ j% X' _. _end  u/ h' B2 ?  Y( X. B, c) ]
其中定义道路的句子,如下所示,是什么意思啊?
& ^" a- X' y3 r7 c, c set roads patches with
- A3 m5 H4 Y7 f9 i- L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) T: V8 k. k: s  u, O, `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 d2 f' ~7 i9 x1 \  K" {. C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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