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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。
& v5 ^. `( c* W3 T" i2 `netlogo自带的social science--traffic grid这一例子当中,
+ R; C8 E7 t" |; l. Y, E$ [globals; g" v) s. w6 s, m" D  S
[) r- z& e( ]1 H0 @/ P3 j, A: i8 ]; E
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. M4 Z+ y- k8 Q  ?5 B( v/ Y  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 o1 n' s8 [  _8 r" d5 j
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. M1 l; |9 H; p. G
                           ;; it is to accelerate or decelerate; b; A6 ?8 B; t
  phase                    ;; keeps track of the phase# Z' r0 \7 x0 V% x9 ^/ E" U4 I
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: {+ C! c- Y; X% L: t% X9 |: p  current-light            ;; the currently selected light! s: v: @: Q8 ^; D: b& |+ ^& i
. s4 d. x, ~' I. K
  ;; patch agentsets
2 y" i( F' G1 m8 M* Y8 p( J4 B  intersections ;; agentset containing the patches that are intersections
7 j5 x" C% A: S  roads         ;; agentset containing the patches that are roads
  {! n, l8 Y) {+ X]
" H: Y9 n' g" t1 X  [! u* r5 I5 |. ?
turtles-own
1 ~! ]4 L3 p. m0 C5 W- D" _[
7 W& z# s3 A" f  speed     ;; the speed of the turtle
2 Q: U9 e9 R6 k% G1 G1 p: {, `  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 u! [1 Z+ g0 J- r  wait-time ;; the amount of time since the last time a turtle has moved& a6 L  G& X: d
]! y5 I5 j$ F! j- _( z) ?
/ H# d$ Q  |% [; {0 E# S
patches-own/ N  t' k, t* }' f
[8 _" v: x8 {  W3 I) H
  intersection?   ;; true if the patch is at the intersection of two roads# E8 y8 U1 [5 K
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- D: R/ p. y+ f7 r
                  ;; false for a non-intersection patches.5 K+ s5 }/ O' p! J3 O) ?
  my-row          ;; the row of the intersection counting from the upper left corner of the
2 k" J) I8 q* A4 n1 i                  ;; world.  -1 for non-intersection patches.% S8 @9 X) \$ T2 r8 f
  my-column       ;; the column of the intersection counting from the upper left corner of the7 ^- p, y3 z' k7 [
                  ;; world.  -1 for non-intersection patches.
6 r9 O) _' c) o* S- B' ^$ S$ x( t  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% W1 u9 _6 L' g9 N5 H0 [  auto?           ;; whether or not this intersection will switch automatically.' r3 ?3 r# d) J9 D
                  ;; false for non-intersection patches.# G* ?# a' g% C2 D" y9 |2 g* Q
]. [( M' }$ z$ X8 f

  w( O2 t' t) \4 X& x; r7 y7 }( D- x+ ~0 P# i& _' L
;;;;;;;;;;;;;;;;;;;;;;( Q/ D9 x4 Y9 X" X
;; Setup Procedures ;;
7 ~' A9 x" t& F1 i# i& i;;;;;;;;;;;;;;;;;;;;;;9 _( }$ A9 _& d, F
- R( s9 O- o: x& I, M. }- u
;; Initialize the display by giving the global and patch variables initial values.
  z# p4 Y4 a) j* X/ \4 P;; Create num-cars of turtles if there are enough road patches for one turtle to
  g  z% O1 X6 s, A$ n+ X, V;; be created per road patch. Set up the plots.
! F' ~& {8 P) K5 u# q3 V1 ]! cto setup$ |9 v8 G% x1 p1 Q* O
  ca
/ Q# e7 _# a' [" [4 D  ?4 \5 [  setup-globals5 G, c' N6 j! O6 K; r7 T
, h8 _' e1 p8 h: U
  ;; First we ask the patches to draw themselves and set up a few variables
0 k4 N1 N& E" P- T+ p) O  setup-patches
+ j& e! {. ?0 @. J. Q7 e- v+ P  make-current one-of intersections- {/ R1 `9 f/ [2 w' G" j0 ^5 W
  label-current
! v7 A/ s& w- g4 b7 f" y, H# _8 p9 h% _  k8 }' _! s
  set-default-shape turtles "car"% C) M; M$ q! o' t3 j$ U  H

( k* @; z5 n. V4 _* i  if (num-cars > count roads)) j" R4 u2 G/ w: E( O. V: S
  [
2 z* o8 U* Y/ }. [% _    user-message (word "There are too many cars for the amount of "8 v* R) i& m2 v4 ]0 ]9 J+ O
                       "road.  Either increase the amount of roads "
2 A* b+ Y7 h0 u# M6 q                       "by increasing the GRID-SIZE-X or "
2 y  G' j0 X8 ?' l4 U                       "GRID-SIZE-Y sliders, or decrease the "0 I2 R7 G2 V4 B
                       "number of cars by lowering the NUMBER slider.\n"5 w8 g6 |" v8 _/ k# }' C3 D5 E
                       "The setup has stopped.")
: j6 [! ~* u5 ?# }    stop0 ?* e( j. g  A  N; D
  ]
% {& B* y) V3 @: R+ |: @' b4 C# ~
5 Y6 z5 ~- L# W$ t2 i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color- ]5 U( i2 r2 N
  crt num-cars
- T( l; A# f8 O" U  [
" W+ H0 p2 X1 O: }- X( m    setup-cars2 i! v" W9 [# v1 h; }% E# q
    set-car-color
; ]6 e2 y. I/ h# E. E9 {% w    record-data$ s; C! g: l/ M& {# g/ |6 ?+ P
  ]
( M  }6 t, I+ x/ i2 @/ d) {7 C1 T0 O
  ;; give the turtles an initial speed% g8 q5 l1 C3 e
  ask turtles [ set-car-speed ]
. d6 a( Z" t6 o5 ^  o
, R6 i: |! R; U) e& f, i  reset-ticks9 O& t- ]& U5 B* e
end
5 J* l9 J: _+ J, }4 @
' x3 W1 C4 G- ~! I( U( n+ d;; Initialize the global variables to appropriate values# i1 k! x% k$ ~; R$ q
to setup-globals: j" x4 k& J" I- ~) j  ]
  set current-light nobody ;; just for now, since there are no lights yet; Z6 F2 N8 D$ |/ u. I
  set phase 0% a$ o* Y7 N" S0 M+ w: ]) k
  set num-cars-stopped 01 u9 a: P9 m$ W; ]! B- S2 P
  set grid-x-inc world-width / grid-size-x
3 R5 O8 e4 T+ J) M( v) z  set grid-y-inc world-height / grid-size-y4 B8 K2 W: a0 f* l# C+ @

2 x  Q6 [' ?% e- `* \# H& J8 {  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% }- S6 `* g1 T3 O! z8 I! E% E, L  set acceleration 0.099% j& c) Z: w% X( m
end
* F! C  q& C% N/ `
1 F$ @0 z6 z8 Y' c8 T  ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,# y1 C/ ~/ d8 L# ^
;; and initialize the traffic lights to one setting& {( R; z  X# F6 w
to setup-patches8 U$ z$ ?! b/ q' a% I/ f
  ;; initialize the patch-owned variables and color the patches to a base-color- ^- ?" h+ `2 \% D
  ask patches
2 s9 h. c' U& ^- E7 \  [
1 M7 u# D2 i  u3 \    set intersection? false/ |3 b! U3 }: G! q, O7 S$ m1 l
    set auto? false
5 w( g' p7 s9 x; Z1 E    set green-light-up? true
+ I! V1 T6 U( P+ F  _5 \    set my-row -1
' i2 }' D! ^8 p0 m6 b# ]    set my-column -18 x/ Q. n! x) ]/ I  {
    set my-phase -16 e; O( n9 o8 J
    set pcolor brown + 3
% s& R, c' V# {# g( _& L& Y  ]
9 v# f3 p2 }8 f  G+ J4 N& x
9 B- g' s3 J+ |' B, \8 [3 v6 m  ;; initialize the global variables that hold patch agentsets
: a9 b' h9 s( x  set roads patches with
; @+ R% |# e* \8 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' E6 X+ U9 ]6 D' _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. c8 F6 J) a" Q8 ^: }  set intersections roads with
- S2 }% R6 P! {) M8 `* C2 X    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 h; K/ K0 |  h6 k3 c) g
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  s- x& l1 ]2 |1 W' S& J( o6 z8 |2 W2 t6 `6 H  N$ ?. ~
  ask roads [ set pcolor white ]# O6 r2 U% [. Z4 ~2 o; ~
    setup-intersections$ f( z' t* V# f: G: a
end
4 z' E2 A2 C8 m9 w) N. E其中定义道路的句子,如下所示,是什么意思啊?
# Q' y/ H, Z: n/ [( Z$ H0 G set roads patches with
& \! g! X; _# D7 Y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 y; a( `( X$ C6 x6 L8 R. O! Y% u# q$ c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( E3 f7 i2 q+ j9 j- ?: `9 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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