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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。' h& C5 w4 X, f. \3 w
netlogo自带的social science--traffic grid这一例子当中,
, K# \9 \+ K, ~6 M7 |! Bglobals
  j( {) |- T  e[
2 L5 S$ D6 A2 l" l  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* k" [' S, T, ^  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* f  u) D- @: a) f/ @' X  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
: ~/ {+ U* |0 f                           ;; it is to accelerate or decelerate
! b2 u6 g, [' p- O! u2 T  phase                    ;; keeps track of the phase  p3 i7 M4 v1 v
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 m# c) J0 ]3 M+ D' L6 h. Z
  current-light            ;; the currently selected light
0 Z! C# v! g/ G+ h/ I" s9 Y% L& f: E* W9 l# V* G" g3 D- M
  ;; patch agentsets; {8 [6 A7 @3 {$ r, f- F0 F
  intersections ;; agentset containing the patches that are intersections
3 P% m1 @: S  w4 c  roads         ;; agentset containing the patches that are roads9 M* ^. x6 G4 D* q
]
. G+ C* W4 t! L% X- F& I# l7 \( Y% R* W( N4 L/ D$ l  v
turtles-own
; }0 M  \" H4 w[
$ Q% J; r' W: I, A  speed     ;; the speed of the turtle
, E/ e' L" z  Q3 B  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 [( a5 l% ^: r3 n  wait-time ;; the amount of time since the last time a turtle has moved
" d1 k; {; A' m' l- S+ o4 i# _! N]
" F2 _8 [. H, H' o' R( W1 T0 g' a. m; @
patches-own4 Z  f6 P- I2 b$ G) j' L+ A! x
[
2 @2 t  m/ [6 Z8 s! s7 E  intersection?   ;; true if the patch is at the intersection of two roads( O! D; @% X7 a( I
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
  m- g$ x. N  I% }& d7 \* R                  ;; false for a non-intersection patches.$ u( f7 d- N/ z* c, s
  my-row          ;; the row of the intersection counting from the upper left corner of the4 x( m' L  [: L9 g- Y4 K; @8 }6 X, H
                  ;; world.  -1 for non-intersection patches.
3 O) G% J2 A+ |6 d  my-column       ;; the column of the intersection counting from the upper left corner of the
: g0 ^4 d. q+ d                  ;; world.  -1 for non-intersection patches.
# X5 p: s* U3 f# }+ h" U  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 w, y1 O- |- _) e
  auto?           ;; whether or not this intersection will switch automatically." h& ?5 |0 {# q
                  ;; false for non-intersection patches.
* z0 K' `) m  Y6 [* F]+ g: ~3 l; ]1 G5 w

# J9 h! r- c; ?# y0 R
+ O* |/ ?2 o. N/ X;;;;;;;;;;;;;;;;;;;;;;
  g6 k; ^$ i+ b( M$ a' i;; Setup Procedures ;;8 X" A5 v2 f. N  W  ?, ^! T" w
;;;;;;;;;;;;;;;;;;;;;;
  q) \: S/ @/ h$ s* S- S. h( `6 t8 G: B) w6 `( S2 p  I; R* ]* l
;; Initialize the display by giving the global and patch variables initial values.
* r4 f9 [2 s5 {' X  y! C7 x;; Create num-cars of turtles if there are enough road patches for one turtle to
/ b9 t5 L- I- l7 P7 }8 r$ |;; be created per road patch. Set up the plots.2 F( c2 M& I8 Y; I7 m+ C
to setup& X( E! u4 a8 e; p
  ca- ?( a. k. T6 [( n1 [( N) g
  setup-globals
1 a  I6 g; O3 b; l; v6 B+ j! ?* p- O! o/ M* t
  ;; First we ask the patches to draw themselves and set up a few variables+ \+ T9 _- S8 F2 P4 I% M) P6 W- D
  setup-patches( F& T( ?5 x( C2 g
  make-current one-of intersections
8 v8 K# s) X: o# K  label-current( p! ^1 B* M$ w; t
; u+ W4 C) [; f
  set-default-shape turtles "car"
6 x; x: Y- e' W1 j' P; c
! R6 Z' r6 e8 d! d/ E0 J  if (num-cars > count roads)7 n% {) C1 J' B$ M
  [1 O$ J3 b& e( _* E- b
    user-message (word "There are too many cars for the amount of "7 ~# o& l  _% _
                       "road.  Either increase the amount of roads "# D: u4 E/ a7 |7 f( \
                       "by increasing the GRID-SIZE-X or "
4 M8 t6 ^, i, |" R                       "GRID-SIZE-Y sliders, or decrease the "
; v( @9 N* S1 |" M. D: O- \- I                       "number of cars by lowering the NUMBER slider.\n"6 c, M2 w$ Y+ t8 g
                       "The setup has stopped.")
' M& I3 u! N2 [1 f4 U" ~    stop
+ Q: K, ]! f- Z$ g* `6 j% p$ l  ]7 J( |# [  g& I! ?$ R5 G. \
: L: @6 \( A; w: o
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: n/ I3 H+ C. V
  crt num-cars' o6 V/ e" Q, t- N
  [6 k3 m+ W# z# w2 E9 \3 }
    setup-cars
/ c5 g; w) a" e    set-car-color
1 D( t) W3 i, x# [2 I8 }    record-data
' e1 `/ F' X6 ?3 M! D+ r8 _  ]: U0 O- s- _6 |4 X5 ?9 o. I

/ n, ^% J. w0 t- _; [* _; X, c# r  ;; give the turtles an initial speed
: a) [* F( ], t* R8 c' n2 v  ask turtles [ set-car-speed ]: l: ^2 y* ^2 C1 E, r+ \0 u
1 b, ?! U- m% \& Q& a; ^
  reset-ticks* B2 q& S- m" j+ J+ a
end( z' M# X6 t, y$ D# y' j7 A/ G

) c( A( c3 q- E' B;; Initialize the global variables to appropriate values( i# k* N1 y! h. D
to setup-globals
6 [$ |( c4 Y  _9 [; p+ v6 C; F  set current-light nobody ;; just for now, since there are no lights yet
. X0 Y" u, r- Y5 T. K8 a2 Z  set phase 0
3 m: l. D3 l: H2 W  set num-cars-stopped 0  @/ P4 W- N& @, I" }
  set grid-x-inc world-width / grid-size-x
* v  ]. H9 l$ B) A% `  set grid-y-inc world-height / grid-size-y1 w( t  v( o$ Z# }$ O) y- A0 A
) x9 [( u( u9 L/ s
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" k% x9 I  P5 o& u2 ~  A0 C  set acceleration 0.099
5 C" Q% B5 K1 S: p3 B0 Cend) z( F1 l6 [4 W$ Y- p
- z) u5 h" |  [2 {3 A0 e
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( {3 y& b6 g& J' s0 V;; and initialize the traffic lights to one setting6 |$ z4 ], a( R% \7 |0 a; Y/ }0 B
to setup-patches
. {" P+ }9 e( _  ;; initialize the patch-owned variables and color the patches to a base-color
, B$ V9 w  S' U+ }! N+ O" X  ask patches
3 G, g# l1 J* ~  Y  |  [" j' [! S# s. C* C7 z% _
    set intersection? false' G7 |+ j/ d% i
    set auto? false
  \# o* q+ V5 g6 V    set green-light-up? true9 o0 j1 O% U3 K3 ~# Z
    set my-row -1( i' s' w2 G7 f" R8 d
    set my-column -1
* G* A6 e5 i7 s& M& X' x    set my-phase -11 Z& f% Y, a) D. W# I" \( [' V
    set pcolor brown + 3
3 U9 k- x9 w/ j7 N+ s( B  ]0 G5 @2 y, q0 ^8 _, L
/ ^% N2 A1 {7 ]3 d% @9 S) E
  ;; initialize the global variables that hold patch agentsets* ?) ]7 \$ L8 [
  set roads patches with
4 c' y& Z* o( w) h8 \! T( O0 Z; J& G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' x, x% f4 \3 x* F, u- _. _
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! J9 g' g4 `" }$ B; Q/ ?
  set intersections roads with
# ]6 U( e. f  V0 ]% B1 S1 R# R& F6 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 Y& W) B3 B" ~* F2 w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ J" i9 P* w# }4 f4 K/ D8 Y# I
0 M  M$ K# i  }& J6 `2 I' \" x3 e
  ask roads [ set pcolor white ]
1 h7 r) t3 I: V: n+ i' b' q    setup-intersections- X' c6 V5 l' E
end
7 b# y9 {( U# |0 K+ p; |其中定义道路的句子,如下所示,是什么意思啊?
1 A/ A8 {& [" r6 r3 v; _! M: R set roads patches with3 [0 w4 `1 I6 k$ \4 Y; t" `+ y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 {1 C. y+ P8 l' x5 c4 g! d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 o! @- b6 j% \9 w
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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