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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' k& S/ |- h1 y! ?
netlogo自带的social science--traffic grid这一例子当中,
, x7 G7 k1 z- m# M$ F$ |+ sglobals
! i- C& x5 \4 r' v[
0 A% l  Q8 \" v  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 {# `9 S' E5 H0 d" c  l, J( D9 E  grid-y-inc               ;; the amount of patches in between two roads in the y direction  s3 `- o4 o; d9 o; r* Z9 x; o
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( B' g: ?! j' k& H                           ;; it is to accelerate or decelerate
& D6 L' h1 @# r5 u: R( P  phase                    ;; keeps track of the phase
8 T+ a* C* \% P3 A  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 J1 T* ?1 Q9 T. @  current-light            ;; the currently selected light
+ y: g* q1 E. w! G
& g# b! X2 q# n1 h. m9 |( g+ U  ;; patch agentsets
, e' ?3 {. ~% F# Y& @4 x' F  i  intersections ;; agentset containing the patches that are intersections* z& H6 C! i# m/ C; e1 R8 `
  roads         ;; agentset containing the patches that are roads& l0 |! \9 S; N) f- V
]; T3 D" A9 \  F; k: x
. B$ E: T9 X5 T& b$ q& G' b
turtles-own
6 M& R" B$ n% b7 }& F3 E$ L[+ j, B; d+ o9 @- W9 l9 R1 ^% s
  speed     ;; the speed of the turtle
( Q$ [% Y3 F& D# b( t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# p, R+ U/ D. h4 t6 z& T9 O  wait-time ;; the amount of time since the last time a turtle has moved
2 b9 k+ x7 r- T# Y9 b]/ N0 [1 C1 C; F, ^- H
, ^3 \1 t+ y) L/ B
patches-own
3 x+ V/ O  ^) ~6 V, V[
# X( n- U+ t& p+ g, r  intersection?   ;; true if the patch is at the intersection of two roads7 T2 y8 }: ?2 ?. B7 g
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
& }! K. o+ C% |4 L                  ;; false for a non-intersection patches.
6 ~% [5 _+ o. o, C  my-row          ;; the row of the intersection counting from the upper left corner of the: ~, L- L9 g  v  E$ H
                  ;; world.  -1 for non-intersection patches.3 \, _1 {) U9 q1 f. w
  my-column       ;; the column of the intersection counting from the upper left corner of the5 I) i; ~+ H& p+ W/ v
                  ;; world.  -1 for non-intersection patches.
1 T& k+ r, W1 c0 [( l+ b; G  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; W! f3 O$ J" B% c  auto?           ;; whether or not this intersection will switch automatically.
- B: t5 W  q: @: i% j2 m3 y                  ;; false for non-intersection patches.
! r! ?# H) M3 W4 N1 P# v( ]]) _( [; V6 }/ {: H& X, A
$ F9 Y2 g( V8 q  ]( O; c- e
* M+ ]8 L6 c4 _7 k+ h" i
;;;;;;;;;;;;;;;;;;;;;;
. M: G. ]$ ^& d0 i7 b1 j;; Setup Procedures ;;
4 `# `, A! D- ~+ N7 q: H;;;;;;;;;;;;;;;;;;;;;;$ Z" F  F5 C* N& _* K

: ^& i+ C/ @0 j+ R, C;; Initialize the display by giving the global and patch variables initial values.
" J  n/ @! N: c7 v;; Create num-cars of turtles if there are enough road patches for one turtle to1 n, I6 ?: I) a$ o/ x
;; be created per road patch. Set up the plots.
3 ~" \) k) [3 [) q" Z* oto setup9 g+ `  u5 ?  P6 T3 ]" D/ h
  ca
( W  B. v  i2 Q* Y# h9 e+ Q  setup-globals4 b- t+ x( C3 h3 H' [4 ^

# a3 H$ e, S) P# H  [, ~  ;; First we ask the patches to draw themselves and set up a few variables
! s8 u: J6 I- E! w6 {+ F. W+ z  setup-patches
% `& R, ?5 H+ [9 @- s2 G6 l  make-current one-of intersections
8 D: a) P8 @5 q( P- u; D& a+ n5 C6 H  label-current
& F& P" P6 z' |4 U( b
- Y% J  J) _2 q& Z$ m: h  set-default-shape turtles "car"
5 h& s  m1 C5 g8 q0 ]* m1 O
* W: f- Y2 e5 i+ n) K  if (num-cars > count roads)+ u$ h- q. l+ q- k
  [
% V$ g. f1 J. U: C    user-message (word "There are too many cars for the amount of "
: X0 B* D- v# q0 K4 i4 u                       "road.  Either increase the amount of roads "
4 M; g9 J2 y  G                       "by increasing the GRID-SIZE-X or "
; c% O  `" S7 e7 r( r* B: x  P                       "GRID-SIZE-Y sliders, or decrease the "$ \" Y+ z9 _" j( \
                       "number of cars by lowering the NUMBER slider.\n"2 B. D3 c. U8 E0 p( t/ l
                       "The setup has stopped.")' i$ n) Z" I$ k) b3 f
    stop( n" S* ^  N* ?: h
  ]0 x; \1 D& j8 R! i$ b* r  _
7 K6 Q! a8 d# k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 N( ?2 W# D! d8 ]* m+ }2 y1 q
  crt num-cars2 B( a! a& s! E, y, p9 P
  [
: I/ x+ _4 h& r) }+ Y3 y    setup-cars
5 v  _( P  h, A3 n    set-car-color3 F' p$ R; V3 }
    record-data; O$ z  ~8 P( h0 ]7 W
  ]
5 b" S/ s: y3 h: }) F6 M/ z% y
2 H, S5 k9 }& h4 E$ i  j5 ~  ;; give the turtles an initial speed
& l) k6 [8 \# M2 T& Y; S& N' j3 w$ z) r  ask turtles [ set-car-speed ]
& @$ G7 ]# G, Y  K# s: ~1 K  F6 F; N# Q8 u6 l# h0 W
  reset-ticks
$ z# Q8 p5 K  J  ]end2 Q0 p2 Y2 Z" M

/ x8 k- `0 S) {$ V;; Initialize the global variables to appropriate values6 G) B, T( b0 w8 a
to setup-globals' t# W. W9 s1 Z& E0 h1 n1 V/ N
  set current-light nobody ;; just for now, since there are no lights yet
" p8 l9 n4 A0 j  set phase 0# z& n6 F$ @$ `8 c1 b
  set num-cars-stopped 0: C/ Y) |* z0 M& j5 f
  set grid-x-inc world-width / grid-size-x- J' |, ?3 {9 N' }0 d  R& o
  set grid-y-inc world-height / grid-size-y0 [( A; u- N7 b: G

" ~! X7 n9 e4 R4 [8 e  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
0 r) X2 ^! z2 b) _; r' q  set acceleration 0.099
1 v; H, O0 R0 Y) _( Wend
& l4 e; G0 V4 ]
0 [. e& A& }" p2 A1 k, @9 L! b;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! F* {% e4 q' U" }) e;; and initialize the traffic lights to one setting' y3 M. L) _7 U
to setup-patches, M1 o3 J& E0 ]: c4 ?
  ;; initialize the patch-owned variables and color the patches to a base-color# U9 S0 d8 D8 x3 k. o5 O; o
  ask patches
; L' @- x0 Q1 |* I( c* D! O  [/ ]# z" V& k" D' I9 Y
    set intersection? false
& M0 p8 f5 H$ b    set auto? false
6 v- Z8 {! q5 h5 z( n$ k( K& |    set green-light-up? true
  E" s1 z: |/ c5 B6 l0 J# ~1 s    set my-row -1) Z8 t6 t' ?' w
    set my-column -1
) o. ^$ S- X# K    set my-phase -1# `/ Q4 j# G( `2 k  `
    set pcolor brown + 35 Z3 o0 z( f9 A9 W4 \- B" ^
  ]
. n% y( J( t- p8 z1 _! C8 j3 z! h2 N  }. D2 u9 r1 r
  ;; initialize the global variables that hold patch agentsets+ L7 M  Z  I* j" N
  set roads patches with4 \* m& K# _) a1 r
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. P7 d4 Z& X2 `. ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 w8 K& e  k  a1 J) K: P; H  set intersections roads with' F% s8 r' U! [2 M! F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- U* a  y9 M0 c& T0 i0 J4 c  a    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  E; r1 ?; N0 s4 }& b$ a9 B
4 Z" r* O0 j3 w9 h* r
  ask roads [ set pcolor white ]
0 E; E: u* n/ x    setup-intersections- h' [: m  X8 Y' ?
end0 [0 J8 l% \+ x. h* J' V
其中定义道路的句子,如下所示,是什么意思啊?
' u% ~0 T9 x+ D set roads patches with4 G$ l* E3 u0 I& m6 V  C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  Q. g. X; F& ]- D+ h* O" H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& A) u9 o2 s( t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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