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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。$ J! O; w% `" i( e1 ]+ b
netlogo自带的social science--traffic grid这一例子当中,( E% r0 x$ r, J( c' p- L! ?* c
globals1 L: O1 f4 ?. d
[, l2 I8 h. p' l
  grid-x-inc               ;; the amount of patches in between two roads in the x direction) V+ W5 M+ G' `3 C! ~
  grid-y-inc               ;; the amount of patches in between two roads in the y direction, E: U( o1 d7 Y# y4 e9 T
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
0 |9 M8 y3 F0 U                           ;; it is to accelerate or decelerate, i6 |7 w& @; G
  phase                    ;; keeps track of the phase; f, z2 @, `5 \1 {1 f. u+ C5 _
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 f: i8 O' k# M( t
  current-light            ;; the currently selected light" _. [$ f0 V/ b& N' U$ C- O
# X( ?5 p; M( l
  ;; patch agentsets
" ?- \0 \% i! E  intersections ;; agentset containing the patches that are intersections
1 \: K' U5 c( n6 |9 R. x  roads         ;; agentset containing the patches that are roads+ w* a' H6 V: k! E& w4 G* g3 C7 \; E
]
5 j" g7 m: R7 g3 x3 e
- W4 F# m" Z9 `4 U+ ^turtles-own
8 H" w; I- n5 g; M- ^& a5 f3 [[; @' K/ q, o0 o1 g
  speed     ;; the speed of the turtle
3 @9 K) ?; k& P& v1 _  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. _/ C) v/ r8 j8 \: y; h$ L+ a  wait-time ;; the amount of time since the last time a turtle has moved
) A7 G) `9 `# W+ S, R0 d* O. `* q]+ Z9 r) X/ W8 Y# i9 z' P! }- X; r

  Y) |! U, n% ?$ Q% v. N1 Apatches-own
- \  R: J# a3 F- P# Z! ?. b[
; x+ a: E/ |9 U+ R  intersection?   ;; true if the patch is at the intersection of two roads: {2 D" z9 Q& d4 j
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# [' W: D8 l' q, u
                  ;; false for a non-intersection patches.$ u( Y  L8 R& o1 _* v! r
  my-row          ;; the row of the intersection counting from the upper left corner of the5 L! I( N$ ?6 N) c- s4 q. \. ~
                  ;; world.  -1 for non-intersection patches.
/ d4 A& r% \- Q' r  my-column       ;; the column of the intersection counting from the upper left corner of the& n, l% E8 y. O: D/ X% _8 x
                  ;; world.  -1 for non-intersection patches.
$ F' @8 S9 ^9 T. C# Z* H  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( B  G! Z. D( T  auto?           ;; whether or not this intersection will switch automatically.+ v$ l  h4 |9 q3 h/ ~0 u
                  ;; false for non-intersection patches.
$ X% c% ]2 w2 X) A) ]4 [# H]2 x  j- [8 \% x! {6 F/ H$ h/ J. i3 J

' B7 V( X, \# n! Y/ l; Q! [$ }: k6 y( o7 }
;;;;;;;;;;;;;;;;;;;;;;# K& D% |# {6 R  o4 U
;; Setup Procedures ;;
2 E$ [6 F4 F  S. a;;;;;;;;;;;;;;;;;;;;;;
* S0 V# ^/ G( C* G: y, f4 C& i' I3 y' _
;; Initialize the display by giving the global and patch variables initial values.. G6 o: A# K; X0 b! |
;; Create num-cars of turtles if there are enough road patches for one turtle to
7 _9 M1 y% U1 w5 F;; be created per road patch. Set up the plots.4 ?" x8 k& a0 N7 s! u6 U
to setup  k& K& C2 H. b% l$ B: t
  ca1 F+ g( s4 b: y
  setup-globals9 J+ B; v) p8 h+ F* M* X
2 ]9 [7 G) B; k! R+ A# x2 o3 v4 ~
  ;; First we ask the patches to draw themselves and set up a few variables
1 X! U# D1 V! U0 u0 C  setup-patches* L2 Y8 T1 E2 x" {
  make-current one-of intersections9 k& B+ v) n) d4 s& Z) \* c
  label-current& b& a1 J% m7 X
6 J# g' m! L, ^# N$ E5 `. F
  set-default-shape turtles "car"
* _5 W8 W+ t& n! e7 w1 M1 |) y
+ Z0 G; `& n  H# j  if (num-cars > count roads)
7 l1 A1 s! k! e5 Z- ?* p; D6 x  [5 G# p) T' ~5 O! O+ {2 v2 U
    user-message (word "There are too many cars for the amount of "
- L; ^: ~0 N  f. l6 m/ y0 a( d  n' q                       "road.  Either increase the amount of roads "' t2 G$ o7 D6 Q$ L3 D
                       "by increasing the GRID-SIZE-X or "$ {% _+ E9 Y, A8 C; o6 N9 S
                       "GRID-SIZE-Y sliders, or decrease the "! q$ z1 T+ N1 E1 H9 E
                       "number of cars by lowering the NUMBER slider.\n"
! b9 m/ r1 u5 t& r                       "The setup has stopped.")
* W+ Q& N1 [! I    stop
: m" X% p4 v4 y) j  ]
0 M- U' H5 A) m% q7 ~2 M
& N, E$ Z% p% C- [& O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 c% ^# j/ Y5 p/ T/ r1 ?
  crt num-cars. W& a" u! ~1 Y* |8 B
  [
6 I0 ?" \4 x9 D  I! r1 R, D    setup-cars1 @" H7 P* ~  p- P6 z( m) H8 T
    set-car-color
/ X" p/ G8 M, d. |% s4 I! R) _    record-data
1 d% A5 l1 ?/ @4 F0 e2 H0 X  ]
1 Q; T+ C) i/ R' y: y# s" j( }- m+ _* Z! @' n' h, h# \
  ;; give the turtles an initial speed5 g0 M+ O6 d2 P2 e
  ask turtles [ set-car-speed ]
# A! M) R- x: Y4 D1 `. J
  @( x* g1 G4 \# @8 W! M2 T" c  reset-ticks
4 B, F7 r3 A8 m, F: V9 uend- H+ j1 C4 @' s  X& ]) [; V, b

! R0 M/ A$ @( z0 t7 ]! n# j/ I;; Initialize the global variables to appropriate values! ]% p. c$ n/ |9 t+ @
to setup-globals$ a5 N( j# O2 r3 P0 t. R
  set current-light nobody ;; just for now, since there are no lights yet8 K1 H  W( F6 }3 r/ O: W+ G* @2 i
  set phase 0
' P9 q  ]  v% ?+ _" p+ S  set num-cars-stopped 09 M0 |  f8 }* X
  set grid-x-inc world-width / grid-size-x( n$ R4 A9 O/ a9 w, e' N2 a
  set grid-y-inc world-height / grid-size-y
, H6 t, c5 T/ v! c, z6 K. G( G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, I8 F& D/ e* Q0 Z* K  a
  set acceleration 0.099
& k, W. @+ e& ?0 hend
7 }3 H! c4 D* u2 k
5 T, J+ v8 M) x/ {) j;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 j1 Y5 t8 ?% f2 }" ?7 k
;; and initialize the traffic lights to one setting  C% V3 r3 h! z2 f" C
to setup-patches
+ C7 E' \, p- p  ;; initialize the patch-owned variables and color the patches to a base-color
& W6 G  s! o" u, j; q1 L: D& s$ }: o  ask patches
- u3 u. t: V. T, A- L, l! U4 P5 r  F  [
. N/ o0 Z9 x+ k' }    set intersection? false
" b  z9 ?+ B0 V) y/ Z    set auto? false
  v% |' y& e7 [    set green-light-up? true) j7 Z% w0 S5 B/ B# }' M
    set my-row -1
4 x( {; |2 C: j3 K; O, T    set my-column -1+ H) A7 c& {2 v, U' S( e- M
    set my-phase -1
6 X. f, s) W4 f( j! b' z    set pcolor brown + 3
) T' I! m% ~& k& I& V  ]
# z( T6 H. ]/ P; Q: R. T. ]8 l8 B. H, f
  ;; initialize the global variables that hold patch agentsets7 M/ u/ D% q0 p
  set roads patches with# V  G5 F- I) K& t! o
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  C7 j: y5 J3 y% ~6 j9 M) B    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# A" |1 H6 B) G. v! p
  set intersections roads with& x5 E6 D' Z3 n9 B$ B! F
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
8 a1 M; K9 T: W+ V8 e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], }) s" k& R; \- A
  `6 r. }) Z; l( U4 d
  ask roads [ set pcolor white ]2 m4 O$ ~" X2 p8 U( `, a
    setup-intersections+ o3 t* B9 G. E% a& ^0 e' U
end) ^# e1 L+ l- r2 N0 H. L. N' r
其中定义道路的句子,如下所示,是什么意思啊?
* j4 n, g  M/ w( u set roads patches with
5 Y1 F( Z6 O4 u: H! C9 q1 c    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 b- N# ^* b0 z$ b9 X1 N
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 s. l! P  l+ O  V" Q  S7 Z
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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