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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。  V/ n4 [# x" Q: v$ ^
netlogo自带的social science--traffic grid这一例子当中,
( V7 P+ I% m7 W8 \, tglobals
% _" L  c6 C- i) P3 K3 ~[4 j( q- h! a, _2 z" L& _3 ?
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# }& L5 ^. m8 S( k
  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ }! ^) u/ ?9 p, |5 y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  {2 @4 i% h* o+ i( j5 l, x$ H                           ;; it is to accelerate or decelerate
) M- }* J' `- k! z1 d: J0 d  phase                    ;; keeps track of the phase
& P) n- l' f: W& s  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 \2 F% j7 s7 N4 y9 H
  current-light            ;; the currently selected light
# J1 {6 L$ p# O
- g/ `" ?0 E! R& f  ;; patch agentsets
/ q6 a- I! p$ N% L6 ^2 Q+ n  intersections ;; agentset containing the patches that are intersections
/ r  u% {( H% Y# N  roads         ;; agentset containing the patches that are roads
  _  c( A8 V" y' p+ n6 s]
) I: E% Q- }" l. d# ^9 a
) U, A* Y; L: j7 G. f9 oturtles-own% m* I1 d( l" k; T9 v
[% w' p/ J, l* b8 x3 x: N
  speed     ;; the speed of the turtle3 p4 T3 W+ d0 K' Q! q( a
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# e# w' Y/ x1 I0 l5 d$ q0 k
  wait-time ;; the amount of time since the last time a turtle has moved
& u7 O' ?# p. ]0 e) z]
8 }, b8 K7 @6 \$ x) S
* O) Q1 M' x* X4 I& |5 T% a: }patches-own# l! y- I. G( g
[
4 n5 ]) K! Y  c+ v( a( c/ Y  intersection?   ;; true if the patch is at the intersection of two roads' @! B6 q# J/ m0 N! I% {* m9 s
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: e% x1 ~0 Q& q1 i: Y% Z( C( O4 u* R  w
                  ;; false for a non-intersection patches.
$ N0 P* u$ `& X1 @- Z7 I. \  my-row          ;; the row of the intersection counting from the upper left corner of the
3 G3 ^& g. B) w, E% A% d                  ;; world.  -1 for non-intersection patches.
* @, M' F8 S1 p& \2 ~9 g  a6 s  my-column       ;; the column of the intersection counting from the upper left corner of the
) i; |6 ~1 U5 `+ R. ~8 M                  ;; world.  -1 for non-intersection patches.
. ?, J+ `. z) T7 r& p3 ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  e% ]) q5 U2 G/ D  auto?           ;; whether or not this intersection will switch automatically.
( c. |' ]& h% `1 ~5 V                  ;; false for non-intersection patches./ o8 ^  y0 u  X
]# p! i4 Z" X9 B+ S% r# b
6 z8 Y1 n+ @) P& s: E

: X! R$ b% }4 L8 @6 E;;;;;;;;;;;;;;;;;;;;;;: `+ _$ u) M# C0 J& q
;; Setup Procedures ;;) e5 `; J  o6 O$ z
;;;;;;;;;;;;;;;;;;;;;;. j. _# P* ^( C8 r( j! f  D

5 @, R! A- H/ d6 p7 N;; Initialize the display by giving the global and patch variables initial values.
. w( S( U( Z' {: b9 i1 V) f;; Create num-cars of turtles if there are enough road patches for one turtle to. ?) G( w. |/ }, D
;; be created per road patch. Set up the plots.
* {" a# ^) n# R1 [( zto setup
, |1 M- s* m  n# w  ca* \' @" W8 H" D- H, o$ @) k' W
  setup-globals
6 [# z% O$ E  X/ R6 m& ], u# L( q4 }" G3 r
  ;; First we ask the patches to draw themselves and set up a few variables7 p( r+ ]4 p1 G) c. N
  setup-patches
' G. K, n6 I7 @  make-current one-of intersections
/ T6 s  k7 Z! D# h/ S# e; `/ z% i  label-current
# l1 C- t$ _" \% j! s
+ B, r# q  r9 p/ \: r& J% J6 y  set-default-shape turtles "car"
9 s6 c0 u1 J8 t0 \, O7 P* t. `2 c8 M5 I0 m, i: b( t  y
  if (num-cars > count roads)2 \$ V: b3 Z9 h# F& O; N
  [( K  \, h$ Y0 R
    user-message (word "There are too many cars for the amount of "
( O5 O: u% ]7 Z& k0 o% |                       "road.  Either increase the amount of roads "/ ?' q# m! ]; _& E9 H% e4 s! \) {
                       "by increasing the GRID-SIZE-X or "
) T+ G* x0 o$ ~$ n9 H0 Z6 x+ h                       "GRID-SIZE-Y sliders, or decrease the "
* `8 x7 g% d7 }- _, L7 i                       "number of cars by lowering the NUMBER slider.\n"2 ^( m' I2 Z" B9 {% k
                       "The setup has stopped.")
, }* S: A( i  a7 w: I6 _4 L    stop
' I9 ^0 f9 c7 r& r) {( ~- h' W  ]2 a# w3 j+ w& R" b" F$ t( ?

1 M5 m1 q6 H2 Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ y! o/ d5 P4 J; S2 G7 e+ T
  crt num-cars
, O6 m! R+ D" n& z& l  [- [$ }* d: h3 P: Q' ~0 E
    setup-cars% W7 O  O. h' V0 ]. h; c
    set-car-color
6 _' G$ ]. e$ X& R4 h7 k" N    record-data: J3 c9 M/ l& b1 m) M( W
  ]
6 t% k6 C8 o0 W& m% k' j# t
/ _# D9 T4 N: z9 x  ;; give the turtles an initial speed# [6 q/ c: E! u% G7 b/ f
  ask turtles [ set-car-speed ]
- d' m1 {( I3 j0 R1 N# X& d# Y! ?* |3 |6 J; h- E" ~, x+ m3 _; i
  reset-ticks2 e- c' b5 I6 j' [6 L4 I
end
4 y5 |3 S  q3 k* M. I& R
' }! Z# s9 L3 N( |+ k0 j6 a" z9 D3 \;; Initialize the global variables to appropriate values+ ^7 R: ]3 }: \& y
to setup-globals, t( t( q- V" i+ ?
  set current-light nobody ;; just for now, since there are no lights yet5 J- M$ O) ?& W% m4 C0 u
  set phase 0
6 p+ d$ x0 o5 e  set num-cars-stopped 04 C) N" \; \, z# W& G: A4 Q
  set grid-x-inc world-width / grid-size-x
# ?' J2 C, [$ {% z+ q  set grid-y-inc world-height / grid-size-y
1 C1 U  k# a* U, b6 H' E* `( z# V. `
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' k$ I, f% l4 M" L, W# m  set acceleration 0.099
. @5 Z$ H/ `- l  a& S& vend
  y: _" m( Y& C0 \
% b( Q) S9 y% r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 ?5 |/ H% V% ~) W: W
;; and initialize the traffic lights to one setting
% X- _0 }/ A! C9 i% {to setup-patches) g/ g- Q8 S5 \/ Y" I3 F
  ;; initialize the patch-owned variables and color the patches to a base-color
- Q4 L( N# C0 \, O0 L  ask patches. u( \/ f$ g) n- h
  [9 I/ a6 ?% ~0 D  x
    set intersection? false3 ?8 u  _; q7 z' X
    set auto? false9 Q* x+ W, S. E% D' [' x
    set green-light-up? true
- h5 v: U  U) p( w6 s+ ?    set my-row -1
+ C: T( _) S4 o& I    set my-column -1
& }: @. e4 W" {7 n- C; r4 O    set my-phase -1
/ O' l% ]7 t; B: A/ s/ g$ }% U& s    set pcolor brown + 3
7 T. z" R3 A8 _2 K+ c4 M  [. j  ]
/ ~$ Y+ b, V" F: D7 A6 Q, g
) C( I% i% \6 P2 E  ;; initialize the global variables that hold patch agentsets
' `6 P. c  ~8 B" H. L8 S  set roads patches with  `( n1 A4 f1 e- l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 N1 i4 y: k. m7 d1 W4 _2 S* ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 i/ p+ d0 R5 X) C2 v
  set intersections roads with' x' A; X! O( a0 o5 \  T- g4 C/ T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 B$ }5 N2 G: @- Y4 ]4 d) t; r1 i3 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 r6 {1 j5 W" K/ C2 z+ l0 r, v8 k# g' ?9 C: l9 d: E8 s" w  A# p( Z
  ask roads [ set pcolor white ]
6 ~% c2 `2 p; I0 K4 ^5 X& m    setup-intersections
; `% g: B9 Q( B6 G; B: uend
* K9 U% a: L' n+ u2 b9 Q/ L) F1 s" x其中定义道路的句子,如下所示,是什么意思啊?
0 R6 A' r( r: @8 ?2 j/ e& b" V set roads patches with
7 k& z4 J  J6 g+ @3 S( \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. h0 L# h* G# b0 ]/ x4 X( M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 }0 K: c( {3 L6 m5 c% _9 H
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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