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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。- n+ C. G( @2 d1 |' Y$ ]
netlogo自带的social science--traffic grid这一例子当中,
7 B% _; v% U5 _/ x7 n9 y* G  yglobals
2 }, Z' Q4 P, t' U7 C6 {[
  Q( o. n7 o; N4 K  grid-x-inc               ;; the amount of patches in between two roads in the x direction
/ w8 K8 Z2 {$ \- u1 l  t' t  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 d4 m, b8 x' A  [9 ?
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 p3 O! t" _# B" D4 a
                           ;; it is to accelerate or decelerate
2 q' c- m5 i1 J2 i8 T% R6 J2 i  phase                    ;; keeps track of the phase
% U6 n+ d5 `9 G' _4 l0 [; m  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* {" ^7 s; g5 ^. H9 k  ^
  current-light            ;; the currently selected light
$ b. C" q9 N1 i: ^1 q0 c( _, t: l! Y3 h4 x, |
  ;; patch agentsets1 N% o1 M% |3 G2 C; A- X# ]
  intersections ;; agentset containing the patches that are intersections1 @0 a1 s8 ^0 Z9 ?3 b* {$ p
  roads         ;; agentset containing the patches that are roads
+ O, n8 a6 R' ?( f2 y8 X]
( D1 \! R7 m" V7 A/ W. Y2 O7 V0 ^* Z  e( P1 Q* L
turtles-own
6 ^0 i& S7 ]& I1 L9 @. |" v( v[& y, N( z: q' O: E& w
  speed     ;; the speed of the turtle+ S1 E6 G' A0 I" `5 P1 I
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right7 @6 U- G" L4 {/ R
  wait-time ;; the amount of time since the last time a turtle has moved
8 v8 T3 q/ B9 r]
7 z" `$ }) R  |. M3 F
6 P+ `+ q% W5 Wpatches-own
. G# W3 W. w8 i1 ?. j' q[
+ p6 N& H2 M2 y" z5 I8 O  intersection?   ;; true if the patch is at the intersection of two roads0 R: f" F1 H6 ?3 x# a& G" w- B
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 g  A) v( v2 A/ w5 r9 E/ c
                  ;; false for a non-intersection patches.
- {' R9 ]0 t: y. n7 r2 p  my-row          ;; the row of the intersection counting from the upper left corner of the. P5 b# {- k) S. w4 Z
                  ;; world.  -1 for non-intersection patches.) u" W6 U, ^, M  k- c: U& O
  my-column       ;; the column of the intersection counting from the upper left corner of the: \  ~9 l  K. r0 _- y" r# q
                  ;; world.  -1 for non-intersection patches.# L8 A; x/ I- q  i# [
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.4 r/ ]- i  O1 q- g8 M5 |7 D
  auto?           ;; whether or not this intersection will switch automatically.3 T! }, x2 \9 @
                  ;; false for non-intersection patches.
  J6 P7 b4 e& h0 S$ }]! Z4 x4 Q- W3 Y0 u8 K, {+ x

7 h3 e" z; T' y3 `5 I1 P( n6 |) a; d% o7 ]( N
;;;;;;;;;;;;;;;;;;;;;;7 |6 t* [+ I# W7 X/ z% N/ u5 ]( S  C
;; Setup Procedures ;;
' r5 F$ r* ?! Q4 N2 l;;;;;;;;;;;;;;;;;;;;;;$ l; r: S/ y& R/ r: r: q) Y

$ T* _5 b5 o1 x$ `;; Initialize the display by giving the global and patch variables initial values.
: K/ f( Y( G/ S+ C$ Z0 r;; Create num-cars of turtles if there are enough road patches for one turtle to5 z) T7 V4 y) N- C& K; P
;; be created per road patch. Set up the plots.
% `1 {" @" Q/ ~1 Sto setup
8 N  e. W2 F( r  @: Z& ^  ca) f& a  A/ n) C) h0 a
  setup-globals
, P' M4 t+ D8 D2 v
8 [: M; T6 J8 S& p; z2 J4 k3 [  ;; First we ask the patches to draw themselves and set up a few variables
- o& \% J/ A8 D0 E  b  setup-patches& C4 a% |' R8 q& ~) A
  make-current one-of intersections* E' D: J# l* c* S1 h
  label-current8 L; g, L0 }3 T: c5 \- A; ?4 H& G

6 K2 w: F& x7 [5 h7 Q! E6 i. t  set-default-shape turtles "car"9 z1 G; y& u  n) W

5 _/ p  T8 p6 g  if (num-cars > count roads), A2 g, M( n2 K/ W" }3 J
  [3 |1 O) O7 ]# m$ H" u) P
    user-message (word "There are too many cars for the amount of "
5 ?- N. n0 k7 `  E& s6 `                       "road.  Either increase the amount of roads "; b. Z- p6 @/ A7 \2 x! w# J$ b
                       "by increasing the GRID-SIZE-X or "
* d7 Q# `% U# j0 X4 P9 k                       "GRID-SIZE-Y sliders, or decrease the "
6 s* h( V' e' q$ v! s: j                       "number of cars by lowering the NUMBER slider.\n"# Y+ B, U# k* T/ a3 l
                       "The setup has stopped.")
' ^( l$ \: v& q+ }9 B    stop0 n# K" J# g. I2 |, L
  ]
5 H2 V$ {. p/ x, _- g" i3 ]/ t; m, y0 c: t5 f9 N# }& v9 N" Z5 F7 h. J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% y( M% C$ D6 J+ ]* q9 G: w  crt num-cars
0 i0 q1 ^7 c0 C6 y) T# ^  [5 [4 _& l, @8 Z* Z* V4 ]5 ^) m
    setup-cars
9 A$ U0 r  |/ F2 X( W    set-car-color
- ?7 M0 W7 Q% H8 S+ S5 b    record-data# o0 j/ W2 S3 K6 A0 p# {' L
  ]
1 t/ b# o9 w( r: A0 c% z8 l
* v3 s! ~: @. [/ x: T  ;; give the turtles an initial speed
& ?% g9 r& y0 v  ask turtles [ set-car-speed ]+ q; o4 ?0 F- j

: d* A3 q% m5 Y) z4 D0 c  reset-ticks5 W" u2 ~. i1 o" R- t- [" z
end. F, Y& U0 L2 E$ J9 \- _3 Q( c

/ e3 a: q2 e: w, q" r;; Initialize the global variables to appropriate values2 V5 F& v% N! k
to setup-globals
) p: L% N3 M" A+ Y! r  set current-light nobody ;; just for now, since there are no lights yet  A! S0 ~- B' u' h  L
  set phase 0
5 D+ v/ T* T" }. u0 l  set num-cars-stopped 0
( _% a9 h* B8 I: u  set grid-x-inc world-width / grid-size-x
6 G# l) }; O) y  set grid-y-inc world-height / grid-size-y+ s; X- H  V; ?" J; P

, j+ [+ D# `* Y4 a1 j1 z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 R) y7 ~9 o3 F: j9 A+ \6 _6 X
  set acceleration 0.099
5 `) U  k  e2 Yend
) M3 P% k5 g7 L& @* S) t! Q
; ^& l1 W' `8 m; b. s9 D% L2 r;; Make the patches have appropriate colors, set up the roads and intersections agentsets," m% s# |$ H* r3 L
;; and initialize the traffic lights to one setting, \+ W( _. ]' C( {2 x1 ?6 D, Q/ G
to setup-patches
, _5 H1 Z; y/ v; q. J4 X2 d  ;; initialize the patch-owned variables and color the patches to a base-color! K, ~9 B2 G2 O' y" c+ u
  ask patches7 b6 T. r% ~0 U+ P, k
  [
$ \$ H/ N4 T) |6 x    set intersection? false
  v1 C# o2 R% ?( k. V, U    set auto? false9 ?; z: a8 k5 g8 K
    set green-light-up? true
' D$ I8 g7 Q% \    set my-row -1" q1 l  N( a7 P' B+ `' O& {3 y  J
    set my-column -1* b8 r( z! L% V" u1 K# s! G
    set my-phase -18 ?5 |; k# W; S$ J9 F/ f
    set pcolor brown + 3
! Z! O( X3 d' L- S2 b2 _6 ?  ]
( _/ _* [9 D: u0 ^+ u! |6 W
; V+ F% f* b+ w& d  ;; initialize the global variables that hold patch agentsets
  j) H1 X7 a- u& p3 e& v" e# c' A  set roads patches with+ E* o6 @! A( g! d( E. C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" e3 R# x3 u& Y7 {
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# G& n9 ?4 s  o" I4 @* ]  set intersections roads with2 F+ m2 z: |% E. o1 K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 o% D* t, A" j* b/ D5 B) t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ i4 L  ~) S& Q) e; f/ Z/ u
6 }' |  [  d9 b! A$ p8 l+ e  ask roads [ set pcolor white ]
  h2 e& Y/ f8 P" A    setup-intersections
$ I7 x+ a- J4 s% r" Q' ]end' K9 A$ U0 S: @0 h; E
其中定义道路的句子,如下所示,是什么意思啊?
9 o3 c7 ?  _) E0 P0 w set roads patches with
6 n$ b. c( w% H# q: t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" I! m  s3 B: M+ {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 t( r7 G: z! f$ y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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