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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。3 B1 T& x+ g! I' g- D
netlogo自带的social science--traffic grid这一例子当中,
  r' [" ]) o2 Z* m0 uglobals4 P% |, e; D2 G4 e7 e5 L# U
[
) |  ~0 v1 s$ l. o& Q2 U# o  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. ^) h3 z3 R: U6 I, S+ z  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 Y! v3 F9 a- a# p6 P8 Q
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 Y- V$ p; h3 T) m1 L
                           ;; it is to accelerate or decelerate
2 N" p4 Q" i7 S  phase                    ;; keeps track of the phase4 U' n0 j0 S* j' R4 Q( N+ D9 r2 D* F* _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& t3 K9 O4 V( S
  current-light            ;; the currently selected light2 G$ U! @, G" F2 `, z+ k( j+ [
$ Z3 _; Q* t  i% c/ \, m& m
  ;; patch agentsets
* P! U6 p8 ?9 R7 M1 c' a4 w* q  intersections ;; agentset containing the patches that are intersections% k% h3 N/ w, B3 d2 w# x! V
  roads         ;; agentset containing the patches that are roads
: Q) b8 d( P$ a1 z0 q]
* P' y2 L6 p4 g: S5 S  c) Z; T4 V, }& P4 j1 l, S$ E; c: _9 k* t
turtles-own
$ o3 {- e% `$ |) B8 O[- T1 K2 {: b, N; g' |
  speed     ;; the speed of the turtle
2 p5 b* v, u* S9 S8 G" [! B  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& p* @& Z' p* D5 ~8 [( b. Y
  wait-time ;; the amount of time since the last time a turtle has moved4 n; q1 `9 N- f+ {
]
" h9 Q. V2 E2 w: e$ w: D6 U0 [2 r4 D" O; j! @  u5 ?* W2 p$ t
patches-own9 Y& L( r0 p& F0 j% S. O, ?" o
[
6 \( }# j! o* _' O) S  intersection?   ;; true if the patch is at the intersection of two roads
, q. V6 j8 O9 x" u8 \% p0 r) C' V  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ S( Q- P( ~4 N2 y# }( N& v3 Q" f
                  ;; false for a non-intersection patches." Q* \# x9 h2 ?1 f. ]
  my-row          ;; the row of the intersection counting from the upper left corner of the% R2 b) C# {: T, X# }2 w
                  ;; world.  -1 for non-intersection patches.2 l. j( a8 f1 w' D" E' I, s
  my-column       ;; the column of the intersection counting from the upper left corner of the! ~/ V) S& |( l1 o/ o1 k% V7 Z
                  ;; world.  -1 for non-intersection patches.; `5 \! |2 h7 D* K! ^
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( c* Y. w- m" ~  auto?           ;; whether or not this intersection will switch automatically.) Q! h/ i- g2 _( H
                  ;; false for non-intersection patches.  T& K0 g; v2 F; @: G) D- d
]( P8 n' l, p2 x  x( J# |4 Z

; i" [* l/ D) t& _6 M0 p  z! e- o7 C# \$ F* C& e
;;;;;;;;;;;;;;;;;;;;;;4 e: F  K, K  C1 ^  y
;; Setup Procedures ;;+ r" B( m0 j# }+ F) n* O
;;;;;;;;;;;;;;;;;;;;;;
0 [: p0 @" c! \, a& `9 A4 z( k. j' ^, a) c3 ^; r: x# q) p
;; Initialize the display by giving the global and patch variables initial values.
# K, |, q+ o9 y* x  t; d6 i;; Create num-cars of turtles if there are enough road patches for one turtle to4 g2 D8 f8 z5 W  v, o
;; be created per road patch. Set up the plots.
. J8 K# F# w1 |, i6 S/ l# R; `/ _to setup
" ?6 |1 B4 @3 L: m  ca0 L0 ?. u& `8 D7 N" {0 o4 @
  setup-globals7 i; {4 ]( G6 z. l  O$ X

1 n5 Y1 u  e7 d2 O+ c% I9 D7 @6 e  ;; First we ask the patches to draw themselves and set up a few variables
- x3 ^7 `4 E1 O" W1 P; i2 ]8 n6 @) ^  setup-patches9 c) I: O+ A0 B. H
  make-current one-of intersections9 {: R; C8 q/ x1 ~; {7 g& v0 C
  label-current8 q5 S  F7 I$ u  m; h  l- p, w1 a: k

+ L! s/ _' C) M$ A) @, v; e  set-default-shape turtles "car"2 h9 E$ k& x/ T) s# }3 r
9 m5 y3 w( Z2 c* }8 W% _. e- @
  if (num-cars > count roads)$ a7 A; \. l4 s" V, w
  [& b4 o+ g3 k- G6 q& M) t* W
    user-message (word "There are too many cars for the amount of ". n8 P! m6 P. v$ G, a
                       "road.  Either increase the amount of roads "# F6 Q. d; Z% |' h( ~4 d
                       "by increasing the GRID-SIZE-X or "+ H( C0 i5 B" ~* r( u% Z
                       "GRID-SIZE-Y sliders, or decrease the "4 P0 V1 m1 G& \  k
                       "number of cars by lowering the NUMBER slider.\n"7 d$ ^* A% L" q
                       "The setup has stopped.")
5 V7 H1 p" e6 ~    stop2 [0 T; `/ r5 r% P  }, z% b
  ]3 F, A! ]( n  ?3 l
6 E3 x" _+ |$ h  }' f* W5 V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( V: k$ l$ X. K: ~6 [# D3 L
  crt num-cars
) F5 w" ^) g" |+ r. k  [
" \4 a+ M4 G, C# @  }    setup-cars
3 `$ j/ C0 w9 [- ]5 r* F. Y    set-car-color
" U8 V1 G1 o+ o: d0 Y    record-data
4 b- U2 f( s% c$ |% Q) n, O# H  ]
. e) c% ~+ d8 E3 R% L) S. V0 x- f
0 z& G2 r% N7 `  ;; give the turtles an initial speed" R& t3 G" b& l, u! ?9 }
  ask turtles [ set-car-speed ]" h4 F, w  f8 d, y) g: r- N

1 t; {' b! p+ y( Z1 j  reset-ticks, H/ o% R" s) H
end( ^9 C& V# Y9 P* r

& }2 \6 W8 s* U2 h;; Initialize the global variables to appropriate values
: |6 W9 ~6 g& V% Cto setup-globals8 n" Y; S- R8 f: z* P# K
  set current-light nobody ;; just for now, since there are no lights yet
7 q- y( r+ U& J3 L7 L0 @% s  set phase 0" d# R& _! `' t8 z+ u3 r$ ?
  set num-cars-stopped 0
+ D' v4 R  C& K+ Q3 V5 a& i9 r  set grid-x-inc world-width / grid-size-x
, C4 @3 h6 m! `+ y9 L  set grid-y-inc world-height / grid-size-y
  {& c$ {& `- a( R6 y7 B& r0 c- C4 @! _9 |! Z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
, m- N5 T5 `4 h  q7 A  set acceleration 0.099
9 Q0 _: N3 ~' [$ dend, k% f, c6 z0 L# l+ @/ N( p* [3 a

) {$ e- H# G' K) }7 x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  {4 _9 i% i" e3 A
;; and initialize the traffic lights to one setting1 t- Z( W$ e4 L; V5 W/ R, j
to setup-patches0 e' Z7 p' M' X# H8 d
  ;; initialize the patch-owned variables and color the patches to a base-color6 M: B7 S1 n# B6 e# w! @9 a" ^4 S
  ask patches
7 y) ^) I8 J3 K$ z  [& j, `4 h+ Q4 l4 C
    set intersection? false
8 c, n, R2 b8 N4 H7 q2 y( k- {    set auto? false
5 F. l" |5 L2 E$ r" O/ I    set green-light-up? true
; u8 }: O% I5 s: |+ J5 o: P4 J& \    set my-row -1# }8 N# h$ A* d# _8 G
    set my-column -1
" T3 c" e" K" L# Z    set my-phase -19 n6 T" c( y* K' N3 `7 [
    set pcolor brown + 3& K" d; n' h% c/ D& Y
  ]
7 ~* h; b, a; r2 ~& v# b7 G9 c& e+ g
8 [) R( A% g2 i3 o  ;; initialize the global variables that hold patch agentsets/ U* d' M7 d/ W: @
  set roads patches with
# E* P7 c0 x8 F! t2 [. B* P    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% G7 S. r- h: r    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 r' H/ j, a  _0 M
  set intersections roads with- [% p7 `7 o0 Q8 G9 N+ H* b
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. r$ P% ~( c) l+ O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- z4 p( k* [/ s) h/ Z

+ U3 \' @0 |; }# V4 z  ask roads [ set pcolor white ]
9 E2 @3 ]0 P" C- W; ~7 j    setup-intersections
8 {) e2 j: h% _! P/ S( R# |- ~end
6 H8 S3 e; V9 E其中定义道路的句子,如下所示,是什么意思啊?
3 L. [- i- I1 b4 ?. L( y set roads patches with
- x9 p0 x  ^: k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: ?4 Q3 b, Z9 k8 @7 O/ Q. X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* u) s1 F- @8 s' w6 W! n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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