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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。' x! r( K7 T# E4 F# q+ E
netlogo自带的social science--traffic grid这一例子当中,
8 y7 `2 g; u  r& e4 u: ~. u* zglobals& `/ [3 B& z& J+ x
[
" M& |# \$ a6 n7 [+ P  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" b, ?" e' _1 _: h& ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction! @; l; X# Q2 C
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  e9 C. J/ Y# P5 g
                           ;; it is to accelerate or decelerate4 l  L, T5 Y) d! ?5 T( R
  phase                    ;; keeps track of the phase
. M8 q. a& [% e. m' D' K9 P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure( ^6 O" D* v/ R  h: D
  current-light            ;; the currently selected light: c) ^8 q- Y7 H% F

; S/ j9 k' t- y  H) ]  ;; patch agentsets- ^5 ~1 r" `% B; U7 q+ j
  intersections ;; agentset containing the patches that are intersections
9 y' P' L. [% @6 K9 }# |  roads         ;; agentset containing the patches that are roads' M! o# I0 Y' a  j' N; i
]2 M! l( E& `$ ~& B8 A4 f
0 t- Z/ j5 u& y; ]  ~
turtles-own
; x8 A* O. u0 \+ O5 |[
1 u+ x" F5 J$ E  speed     ;; the speed of the turtle
5 ]% G1 A" W& s+ H- @* g" ?7 L- [  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
! `8 \. H* Y/ ~4 e8 t% d3 g5 x: Z  wait-time ;; the amount of time since the last time a turtle has moved: ?9 T9 S* M3 A6 f: }  g& `
]- d8 [- _) O2 ]& S$ M
6 d6 o1 M' j: _& T: }+ P) o
patches-own/ {* r7 z) L! A* S. _/ e, i+ w) ~  v
[( i4 s1 d: `* X
  intersection?   ;; true if the patch is at the intersection of two roads
$ ^- T$ L; d" z& ]" w2 r% @  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- D( v# o. K3 R0 k                  ;; false for a non-intersection patches.; e, W$ l0 c4 @  Q2 m
  my-row          ;; the row of the intersection counting from the upper left corner of the1 f5 ]% D" j- [
                  ;; world.  -1 for non-intersection patches.7 N9 I% Y8 `5 s
  my-column       ;; the column of the intersection counting from the upper left corner of the( B5 i4 r% G' K) B3 X
                  ;; world.  -1 for non-intersection patches.
/ n6 n1 f2 d  M8 s! }) K$ l* j4 l  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: y8 n' R3 M" x/ ~' i  auto?           ;; whether or not this intersection will switch automatically." E1 C1 x: D! }5 P) M9 f
                  ;; false for non-intersection patches.
/ G, t* M. i  A( N! D4 S], `9 i& X- C+ p, e2 D1 J2 b+ T
) u2 S- Z1 y6 ~0 t
+ t/ B% S  n% }0 ]8 w
;;;;;;;;;;;;;;;;;;;;;;3 V' w. U; L; W6 `1 m% X
;; Setup Procedures ;;
4 r) X7 r4 X# n3 W;;;;;;;;;;;;;;;;;;;;;;
* G7 R' u1 \% N' V- i( b7 ^: P( `; y8 u3 E: s; E
;; Initialize the display by giving the global and patch variables initial values.# ?' {% r7 y& o5 ~4 {- ]! q
;; Create num-cars of turtles if there are enough road patches for one turtle to
5 {5 d% l/ W( |' e6 t" g7 f. Q;; be created per road patch. Set up the plots.9 P; B) E, _: W# p# F+ d# M2 J
to setup
' Z3 i, h. z1 P* _; r/ F  ca
* ^, I! S6 F5 I/ w5 @! j  setup-globals
7 [2 x% W+ L% Y" h0 S2 A3 D- U. I! ]& m
  ;; First we ask the patches to draw themselves and set up a few variables; K4 H+ x. m5 B
  setup-patches
5 n7 J7 O' _& k' I  make-current one-of intersections
4 y$ N1 L6 b0 p6 N  |  Y5 X* B; [8 Z  label-current/ C6 e; @: v; M; q

7 D+ {- N) V' S/ e- {8 d8 I  set-default-shape turtles "car"' I- x7 \! `2 Y5 s: e& D
/ i+ k) g2 H4 {2 X+ q: }
  if (num-cars > count roads)4 P" `# t8 C9 e2 r2 F; ~
  [
! D2 R7 I* |( U4 m) q* P    user-message (word "There are too many cars for the amount of "
0 ?. K& f' |8 d8 K2 D                       "road.  Either increase the amount of roads "
: x( [: r# O/ I7 U/ _2 x                       "by increasing the GRID-SIZE-X or "* A4 s  p/ Z0 _5 P0 k) u1 v
                       "GRID-SIZE-Y sliders, or decrease the "
8 t8 Q5 S$ A" g% P1 q3 m                       "number of cars by lowering the NUMBER slider.\n"7 _' T. ~2 `3 h% \* H0 Q
                       "The setup has stopped.")
: q- E/ F. x5 J: O    stop
3 t# Q- U& W1 R2 m  ]. X( I: B5 I8 C6 u; ~6 ]

# i: B% F6 E6 A9 Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 ?$ ~. \% j. g. \- f' p4 z& `  crt num-cars
% U4 X$ W/ Q" R/ i# B3 _  [( w" ]! C9 Z( r8 R3 |
    setup-cars
5 u. b2 X9 P) Y3 C( @    set-car-color( Y9 @+ v' `# C
    record-data
% U6 D3 w6 m) |1 Q3 }  B  ]
$ K9 y( Y" x* K8 `( m, \: `1 s1 E$ m* V
  ;; give the turtles an initial speed2 O$ `/ D) y* j) G6 X& {
  ask turtles [ set-car-speed ]
) ^' Q% X1 [6 y$ M5 g! S- Q& D* q+ \% J; D3 C9 [: U/ k( W& E+ `
  reset-ticks
" H. v& \# T' q/ L. Dend
. ^) s# C+ C7 T  e3 L% y, g
3 c  i4 o& e+ }8 n& x1 L# g9 k;; Initialize the global variables to appropriate values
5 O/ X& H7 ?) zto setup-globals
. E4 {6 e( @# _* \6 [3 z  L  set current-light nobody ;; just for now, since there are no lights yet
- i0 S6 a2 Y1 ]4 L, a; W  set phase 0- U% n9 Q/ w+ `' N6 Z- y
  set num-cars-stopped 0; T9 S- v" L$ R. s! o  a, x
  set grid-x-inc world-width / grid-size-x
3 ~/ N$ }% e% ^$ V* O: k, D$ g  set grid-y-inc world-height / grid-size-y9 y4 w7 ]. `7 L- }0 K; J

. ~. s5 Z5 `5 O; x' u5 m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 C* u( f+ I, y- k; [2 {  set acceleration 0.099; i! }$ C) H% d) H) N4 C# n
end3 [2 @" N; u2 r' T
9 E8 a) c/ I& c: m5 ^
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  |1 T+ F- B/ Y1 M
;; and initialize the traffic lights to one setting- W  s! Q2 J# \( s% W8 K
to setup-patches2 W& [: o5 m+ j% c/ l; u/ ]
  ;; initialize the patch-owned variables and color the patches to a base-color7 G7 l7 ?' Y" @5 y
  ask patches# V8 \8 s  S+ W( A9 u! L) `0 @
  [
% |7 J* U$ b. u! I# U0 W    set intersection? false
7 d9 ?. O1 D' f3 x+ L    set auto? false
0 r5 y5 z# O9 c0 P" l$ R    set green-light-up? true, L/ r- H7 k( M" A" O1 V$ c
    set my-row -1
4 N2 D& A; X0 h& J0 O: \    set my-column -1
( H# J8 c: V9 h9 N+ ~' e5 c    set my-phase -1
) P% f2 m" e6 w- Y: H    set pcolor brown + 3) w  u) v( d( ]  D# ^" ?" z
  ]
$ P# y# v: r5 L6 ^! X  _% _. B3 e  E% K3 `: t; v: O. @& y' z
  ;; initialize the global variables that hold patch agentsets( E( P2 ^# c0 @, I/ u% f
  set roads patches with# j: \" q7 b$ `6 o; @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
; X. F6 o7 R% q: B! t    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 k! d1 H" L3 S9 f' A( @7 L
  set intersections roads with
. n- ~: x" Z0 W7 ?  w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
4 a) i) G2 e% a) v9 v1 I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" L. k3 y& H: r" n6 y( A# H) E- P; ~. a5 ^' z
  ask roads [ set pcolor white ]
* l$ _0 {" J  N7 A# M    setup-intersections% \2 h, q/ B6 X7 D! L
end% T5 c+ [7 B% L6 z, n2 r6 A
其中定义道路的句子,如下所示,是什么意思啊?
& b  K, K, h  w0 u7 {/ C set roads patches with$ C0 s) y* M. |( v* n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# u" m# @# t' @: j  S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& j6 O: K0 \+ ^, n5 T5 b" 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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