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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。& D5 f5 Y- Y: H5 J& M9 W
netlogo自带的social science--traffic grid这一例子当中,
; N  K  _+ `; E- m" M" Aglobals
/ d( j6 ~9 q2 U; P1 B[$ P* Z* ]- @* O+ l8 a2 l1 g0 n
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 X$ c% f+ o; j8 ]  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  q1 P6 n+ h- j. \" g8 R$ @* M9 {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( G" q. U- ^+ b" q# _# n                           ;; it is to accelerate or decelerate2 N- b+ R* p( D# G2 O
  phase                    ;; keeps track of the phase
* m3 M7 r  v& N1 ]  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 ]% E; w4 W2 F  current-light            ;; the currently selected light+ ?  q( d+ k1 p' p: u/ m
2 A5 V: H4 Z- r2 m  |
  ;; patch agentsets0 [0 z; `# F; r: N8 Z4 A: T
  intersections ;; agentset containing the patches that are intersections
6 f4 Y. B9 j0 h& G4 y+ c  roads         ;; agentset containing the patches that are roads
$ ~- t# _) H5 F8 b2 [: c  h]& i( R. u; T0 l  L. A5 W

0 S* V. D! f& b, Z4 K/ Fturtles-own* L' D% n1 @' Z4 m' S( d
[' F* y9 N# g  e. C  ^
  speed     ;; the speed of the turtle6 T' |& p7 A" K2 e! {" k" ?
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# o& m# N% J7 x1 _  wait-time ;; the amount of time since the last time a turtle has moved
, c4 |+ p; _' j2 s* w]
0 T3 i( d/ I% s5 k7 ]# |* P: j+ c
( K! ~% i3 w' e7 X& l3 e3 I4 V: a0 S5 Epatches-own" k5 U" C# ~4 P& f
[
2 w4 @) p& \* w  w  intersection?   ;; true if the patch is at the intersection of two roads
; n' E( a; V8 a4 a; z8 B9 M: y  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.  D: @4 u# d8 A* H: Q$ a( r, X' a
                  ;; false for a non-intersection patches.
' g- F& C, H! V) e! g/ G  H' l  my-row          ;; the row of the intersection counting from the upper left corner of the7 p8 w* u1 J6 w! j: J
                  ;; world.  -1 for non-intersection patches.# \, d  P" n7 W9 X
  my-column       ;; the column of the intersection counting from the upper left corner of the0 q8 E8 p1 d/ p
                  ;; world.  -1 for non-intersection patches.
$ W) f& G$ h; `- B& m5 ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. q2 S5 c7 L" k" G  auto?           ;; whether or not this intersection will switch automatically.
6 i, T) L4 v$ t' R9 w1 Z                  ;; false for non-intersection patches.2 Y, N/ K- s& V' w
]
" f6 G/ r3 L7 y5 p- i! F6 `* [. X2 X% ?0 C% [

/ _# B7 J/ ^" q  B" ~* t5 @;;;;;;;;;;;;;;;;;;;;;;
% z' b, L9 m1 L" T" I;; Setup Procedures ;;
) B8 U, ]3 \! H2 k" I;;;;;;;;;;;;;;;;;;;;;;
) O2 D+ v' p1 z; _0 l! E& y0 y" ]; @) z% o( T; M* e
;; Initialize the display by giving the global and patch variables initial values., g% z: W6 s3 `4 m
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 U( D0 q$ @& b* `$ c;; be created per road patch. Set up the plots.
6 c- ]' Q7 w) M" e: Ato setup
* Z8 }: v+ }! M8 n  ca
/ ~5 s& A9 K* s# G0 c: h4 t  setup-globals( o8 p% w( P; K5 }; R( H* q

0 L! t8 `( M3 X8 G( S, c* Q# E- F  ;; First we ask the patches to draw themselves and set up a few variables
2 }; @7 K% D, Y* t  setup-patches
- p3 Z& u# {. P/ k  F  make-current one-of intersections
1 C% k; ~& a% l  H+ x  label-current
- P% T" D- [# W% Q( R9 c1 b
% K9 I- D/ L( n. h  set-default-shape turtles "car". x. ~0 g" ~) F# ?  }7 Y/ b5 V

2 A7 p+ d8 h0 X2 a: U# E7 F  if (num-cars > count roads)
: J- Y. C6 Q4 b  [
+ J4 u9 R, x! R/ A/ ]' K    user-message (word "There are too many cars for the amount of "6 r  \: o! n4 [  g: K, n1 I" }
                       "road.  Either increase the amount of roads "2 ^/ S4 N2 o; {0 f9 Q
                       "by increasing the GRID-SIZE-X or "2 {) L9 r" `4 u7 |4 {
                       "GRID-SIZE-Y sliders, or decrease the "
9 ]1 t0 ^- D9 o3 ?" T3 i; [. n) R                       "number of cars by lowering the NUMBER slider.\n"
/ k6 f& f( t1 y                       "The setup has stopped.")
7 y" v2 ?/ i6 v- ~( k# i, w    stop% g/ W0 @% c* d$ c! S% w% i# y& Q
  ]8 x% Q3 f1 L4 _9 l+ P( ~" \
$ Z6 g5 @" O4 p8 s+ f' Y: G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ l* O7 I( t% q# R8 k0 e6 s  crt num-cars
) V( P! p0 h6 b8 t$ l  [0 d/ I3 Z6 J+ w
    setup-cars
# L) {: A, F, n: N+ e( R    set-car-color% x' q5 S. l  @0 X! L
    record-data
4 h" N/ }& M0 ^+ }% I! s& r" i  ]6 _% x/ N4 w# \! L$ X$ @$ K( W. V
- x0 z, O& d6 ~. H$ t' U$ {1 |
  ;; give the turtles an initial speed
0 n3 d8 C! H- G* \& |% g5 j, v& D  ask turtles [ set-car-speed ]! `/ s4 I/ Q8 O9 |  e* e6 s& k

9 g8 N, X# V0 [' J; j& E  reset-ticks
/ v9 A  W) i$ x/ I* _end
0 {6 ]! R# N/ m: C4 v5 r
. T# G- A, N$ n) v;; Initialize the global variables to appropriate values  X2 C8 T' ?- d
to setup-globals
( U# s! y: e: O9 w4 X0 l8 _) C$ K9 L  set current-light nobody ;; just for now, since there are no lights yet7 i9 H% J, f$ B% P5 u
  set phase 06 }- d% r; O; G
  set num-cars-stopped 0/ O/ F; m( [  Z0 x3 I7 ?" V! [: o
  set grid-x-inc world-width / grid-size-x0 k6 w  ?9 a7 l& r  ~4 {
  set grid-y-inc world-height / grid-size-y- i! {9 T8 ^: `" a' Z  q
+ G$ ^+ q; k# L0 K% U
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 C$ O) W  `& d6 i
  set acceleration 0.099
" ^: W+ {6 i& f7 h4 I( G  tend
$ v' o; k' ]' Q0 Z: R8 Y7 L3 G  Q5 Y  P
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
3 H( ~6 E9 z" E' A;; and initialize the traffic lights to one setting
8 i, o$ D1 v! }/ u( V4 Jto setup-patches3 c! H, b9 t* g- r
  ;; initialize the patch-owned variables and color the patches to a base-color/ a: C6 i: y& I  }* s0 K' j1 n
  ask patches! J4 B; h5 B. x7 [+ \
  [3 R. u; w' H4 R' H8 W. @
    set intersection? false
4 k, E! R5 m% F5 p! B) ]& ?    set auto? false( S/ T  J; L% ?- ~
    set green-light-up? true
. p5 l# `7 h& K/ b9 O# {    set my-row -1. w# b) u: K# ^6 V' q2 z2 H4 Q0 ?
    set my-column -1
. Y. x% E: i, _7 E5 g) @$ S% d    set my-phase -1
8 l8 N6 m! V* V  v1 s# `    set pcolor brown + 3
& L  a5 N3 E* E! E4 j. U& @  ]
. d8 x1 ~* Z8 o* W7 h
, ~: ]& q1 m& v+ B% d  ;; initialize the global variables that hold patch agentsets8 g  |4 P% Y. e' L5 X: ^4 T0 j
  set roads patches with. Y. R# L5 j  p6 W# L* t+ l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) o" O, J/ }% m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* m6 Q4 G4 F3 X* `) C7 Q. c* O  set intersections roads with
& L6 m, i/ p5 v! k7 P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ _8 O' s# I8 K* a' G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]+ k. u* d  `( Z' @" @3 l

( I5 E6 q0 O& z2 |) H6 r  ask roads [ set pcolor white ]% M3 z3 H; J+ t: D% P6 r
    setup-intersections1 R' a4 o9 \/ b7 ?; w
end$ h/ ]! v9 w. O% i" e7 x5 B0 {
其中定义道路的句子,如下所示,是什么意思啊?4 l- w" |1 P7 h. k& ^
set roads patches with4 {6 `; m# A1 O- g' @2 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" X% {, F. y* ~4 O2 N; i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 C3 n' D- D1 |/ h; g* }
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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