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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。
) i5 K- L2 A! {% J  ?3 o0 A+ c  ?netlogo自带的social science--traffic grid这一例子当中,
( @' S* L- V8 a8 y8 Y" kglobals
8 _, ?; M' V* h' U4 V[; f; M9 x( F* }% i0 t1 t
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 C: @& `4 w: m1 i$ |: X  grid-y-inc               ;; the amount of patches in between two roads in the y direction! m8 T6 C: N" Y4 A9 r% M( S
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ V( I% h6 r: C0 o2 s                           ;; it is to accelerate or decelerate1 \  m$ K2 W" Y) N' o( T
  phase                    ;; keeps track of the phase
7 t+ K% \7 R+ B  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  n. R3 y; ]! s. K9 W
  current-light            ;; the currently selected light4 |6 P- Z3 G. h- v
$ O# s- Q4 I' T, x" F
  ;; patch agentsets
# u# p/ A& F  K, [/ E  intersections ;; agentset containing the patches that are intersections' S/ h+ J$ `5 e* I9 G/ @
  roads         ;; agentset containing the patches that are roads% P; D. X/ v( N% _0 y4 {
]
3 ]: D" n2 ^* E, v
# U0 g& D# f7 @turtles-own
0 y" J# ^6 ?. q( B8 m$ l6 H[+ @6 }. e4 ]7 @$ E
  speed     ;; the speed of the turtle
6 b- t3 I- c/ O' E& }2 l  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: X9 y1 `$ o. g. ~/ j8 r/ p  wait-time ;; the amount of time since the last time a turtle has moved& t& I" m+ g6 `8 Q
]
! l- A* q; G2 @. o0 {/ J) y, J* q8 ~2 a
patches-own8 L1 h9 ]5 L6 a# R( D3 j
[1 a. n' c8 I( i) F; ?. d
  intersection?   ;; true if the patch is at the intersection of two roads
# ~5 q8 g% V- r  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 \6 ~! V  S1 P& H3 z+ ?                  ;; false for a non-intersection patches./ y  F8 q, c, D5 {7 k! X* Z
  my-row          ;; the row of the intersection counting from the upper left corner of the7 @; K. s: s; L6 ]
                  ;; world.  -1 for non-intersection patches.
3 t2 D4 F1 _8 U  my-column       ;; the column of the intersection counting from the upper left corner of the
3 `1 P3 Y5 `! i3 N% }. v                  ;; world.  -1 for non-intersection patches.
) p% q3 f! |0 [  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' E/ D1 u: u1 l. l; K( n3 }
  auto?           ;; whether or not this intersection will switch automatically.
' S' E' e5 C% [7 Y9 X/ b  q& u/ r                  ;; false for non-intersection patches.
  h- h+ G! ?% Y& b0 G]
# B. [+ i* M8 I% ^0 E3 W( @; ?- L: ^5 }* _1 K

' L# G/ u! C; o! n1 Q$ v* {% Y;;;;;;;;;;;;;;;;;;;;;;9 [  A1 H2 l- X. j: l
;; Setup Procedures ;;2 R9 q* `2 S  Y1 _' `
;;;;;;;;;;;;;;;;;;;;;;8 [+ p) `5 }/ G5 Q3 a, @
- r- U& K! M, j
;; Initialize the display by giving the global and patch variables initial values.6 x0 A" A, T( E- j: p9 I9 k
;; Create num-cars of turtles if there are enough road patches for one turtle to2 T9 ?- X3 S" ^( D* T* e7 K" t2 y
;; be created per road patch. Set up the plots.
5 J- r+ v5 A% C5 `# i0 Mto setup& q" e: v$ L% M% e2 N" J& ^* N
  ca
1 C4 G3 I2 |$ ]/ x, r7 n. R  setup-globals# A; r. L9 b- |! U# G1 D. @
5 _$ [+ C' B- h" `
  ;; First we ask the patches to draw themselves and set up a few variables& B8 ~( b* O0 w7 z8 R( K
  setup-patches& d# }, o, R6 X  Z& W
  make-current one-of intersections& z5 y6 c/ G! y' E2 H
  label-current
5 V$ s* r+ O6 j/ A: ?+ ^4 l8 x' _( d& A
  set-default-shape turtles "car"
% d/ n8 t! d. \8 @" u+ l; U  w* H; A1 s& E: O$ Y
  if (num-cars > count roads)
1 U8 C3 F3 T" v  [
# X/ Z/ L; t* x. P7 I: R    user-message (word "There are too many cars for the amount of "4 `! t, ~1 d/ B4 [  ~; _5 h
                       "road.  Either increase the amount of roads "
) n7 t: f. O. C. r$ a* x                       "by increasing the GRID-SIZE-X or "
! u, D7 |; z1 T                       "GRID-SIZE-Y sliders, or decrease the "; D+ |% w! {) {- y5 z, m- b% z
                       "number of cars by lowering the NUMBER slider.\n") m0 V( S" I8 H! L7 z
                       "The setup has stopped.")3 E/ @: }3 W$ q1 X
    stop
% S2 `) `) M% f" w( Y  ]
8 m: f' r8 S: w( L5 |0 ^% H/ J$ i* N6 S) |: F( |9 y  @5 y1 d
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 Y1 C) D# n$ i# h# A: R7 v1 @1 P  crt num-cars
) b& D) i& }+ y) z+ X  [. B/ [, |+ G- c/ o
    setup-cars- b$ s. p' [% Q: F, B/ Z0 K0 \- Q: Z
    set-car-color# M/ w+ O  e. b  g1 `" C3 i- y( I& X
    record-data& T) _! X% A, @$ v" A2 D& @
  ]
  q: \' k+ [" d3 f! F$ d8 y
  P/ a/ i4 v9 z6 b/ e  ;; give the turtles an initial speed2 [0 O3 r9 U9 C' d% A
  ask turtles [ set-car-speed ]
2 ~' w0 D; K1 K- r
6 o$ Y* J6 ?" Y8 i( [9 M  reset-ticks2 ^+ F+ f4 U& j+ y5 S
end% \) j' U& d9 _! O; o
: }1 T& S' ?* @
;; Initialize the global variables to appropriate values
6 @: ?7 |5 q7 F5 \* mto setup-globals
: k* B0 Z* a* P1 L0 _  set current-light nobody ;; just for now, since there are no lights yet5 s2 P" s. z  ~: Y( ?. {+ H
  set phase 0# e. C% W6 b" X# C0 H
  set num-cars-stopped 0
9 V" O' w. ~4 U5 V# S  set grid-x-inc world-width / grid-size-x
* V2 z, f6 ?6 n' S/ V  set grid-y-inc world-height / grid-size-y
! c. z1 q: R2 ]$ p! }$ b2 ^1 _# V0 |" z+ ~
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ F% t, g- o; \  o( R1 j
  set acceleration 0.099
! e! u* L. V' G! l) s/ v8 mend
  g; a. r. b- o8 y0 v) C1 L7 G# @8 O* a
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  C8 Z- b% B+ L1 J$ m& F" P
;; and initialize the traffic lights to one setting
$ F5 F+ C$ y; m. x: }to setup-patches: [/ e) S: A/ _% I6 W* [, W
  ;; initialize the patch-owned variables and color the patches to a base-color6 ]: L- K4 B: R% l+ H
  ask patches
& K! w. G& m3 n( o* ~+ e  [
9 X" G  E) u( d8 T3 E% k, ?+ D' x    set intersection? false+ }. k% q$ z* i/ y
    set auto? false- g  N" ^3 a6 t+ |2 G4 K/ R9 C
    set green-light-up? true
1 k/ B! @! p# T+ Z- C' _    set my-row -1
4 D, ^4 q# h9 C+ P" x0 F    set my-column -1
0 ^% I, n: ~* V. B  d5 i    set my-phase -1) Q0 \7 g- |  `3 j! g6 L3 J
    set pcolor brown + 3) b  `! y1 Y) B1 W2 T% C# O/ U
  ]; r4 r! W. q  ^
2 h8 _4 x5 ]9 }
  ;; initialize the global variables that hold patch agentsets2 K! d  O8 f9 c/ m
  set roads patches with3 w1 Q0 M4 Z' }. Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ h! \6 q) l( I! |% I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 `9 d" ?; S  |3 ~  set intersections roads with6 [. [$ m% }% f/ A9 a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 \; g' f- e) B* s" w% T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. B: p0 @7 Q$ n+ b% C9 ~4 \3 A0 `; I, N; P1 D" ]; I7 k  v% }
  ask roads [ set pcolor white ]3 o3 K" z( i5 i& c) p" D
    setup-intersections4 d5 f, [' J8 t! u4 v
end1 D+ x7 B& A- y  H% N, n- x
其中定义道路的句子,如下所示,是什么意思啊?
' b* k- K8 c! R. A1 I: \4 Z6 f( ] set roads patches with
( n% R& B% r' N: f5 p. E4 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( P5 y* }; A& H8 D# x( P: V- d; k- C    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ Q& l9 Q, e( M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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