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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。
* `2 H; u  `: f7 ^7 C8 @' q% Enetlogo自带的social science--traffic grid这一例子当中,
  p; c# x& |+ E5 F  B* X  lglobals* N) h0 H% u) h( ~* D
[& ~4 }% g$ d7 ^$ a
  grid-x-inc               ;; the amount of patches in between two roads in the x direction, D* V% \  d- M' \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ f4 m" A) j7 X* \- ^  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; A3 C/ `$ x4 K  C$ ^
                           ;; it is to accelerate or decelerate4 {  y5 ^5 R& o. d# I, }0 B
  phase                    ;; keeps track of the phase0 M1 Y" e0 }& r( m/ R* ]. {
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure& t1 O# w& R" j! P4 o1 t- ?" P
  current-light            ;; the currently selected light6 H# X" Z/ I; x! `% |6 t' q2 _5 h

3 o  R* p/ j% B2 A, ^7 @" \0 Q: s3 k* c/ f  ;; patch agentsets) V. s' t' v4 ^$ o& {7 \
  intersections ;; agentset containing the patches that are intersections
* L' h4 ]7 v6 d( Y+ G4 g/ d9 I, e  roads         ;; agentset containing the patches that are roads
. S; s5 z  @) |! p4 h) I]
2 M! c7 X0 ~" j5 h! W
1 B3 N. b5 D* A/ `, M2 Dturtles-own
$ O/ |* b' M8 v[- o$ A# o. D  l) y# |* k6 x( x
  speed     ;; the speed of the turtle! e! K& N  u2 D4 ^
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 e4 Z9 a) b" f' B$ b  wait-time ;; the amount of time since the last time a turtle has moved
. }8 D8 ]. i! N4 D7 c' i0 u3 k]4 }; J) B! J! z+ L
. ?* Q# Z( b1 u8 X) N. V% k0 C
patches-own4 W/ G8 C0 L* b0 V. b
[
/ k  d5 ?- w3 Z5 O$ W# U) P* s  intersection?   ;; true if the patch is at the intersection of two roads
9 L. {2 E" z& o  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 I, ]3 Q2 h- V
                  ;; false for a non-intersection patches.; \* S! H0 z8 E; ?/ _  }
  my-row          ;; the row of the intersection counting from the upper left corner of the
. n3 A  g8 w" w                  ;; world.  -1 for non-intersection patches.4 d& H. x2 h: j7 u! R5 O3 T
  my-column       ;; the column of the intersection counting from the upper left corner of the
  l5 @1 C( q! o0 ?; e* L                  ;; world.  -1 for non-intersection patches.
) a% Q# q" i* u. l% J: J( f2 h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  r0 z% x* S. c! g5 |' @! F, R! K. u  auto?           ;; whether or not this intersection will switch automatically.
) l7 Z4 c2 Z$ G                  ;; false for non-intersection patches.
  g) t# m! x9 f7 m]9 d6 W0 M& G1 Q
( j  J5 j1 Y- l' B% R

& ^( ]6 [! c6 X;;;;;;;;;;;;;;;;;;;;;;
: `" W2 p2 i: o! ^9 X;; Setup Procedures ;;
! F" g" C: @3 G;;;;;;;;;;;;;;;;;;;;;;5 W7 k) \5 i1 n
: z' v) N: a4 g- m& F* U
;; Initialize the display by giving the global and patch variables initial values.# U) I6 O3 ]& Q7 X; f1 Z
;; Create num-cars of turtles if there are enough road patches for one turtle to2 D0 H# y8 T* U0 q
;; be created per road patch. Set up the plots.% A, E) l& {" _0 A
to setup' A1 V9 k4 Q$ k, _  X
  ca
" ^8 ^+ A% h6 m# v) g1 X8 y7 |( T  setup-globals
' b- {- T& y& T# L( r2 B9 I; x$ m5 w
  ;; First we ask the patches to draw themselves and set up a few variables3 k/ z! m* ]6 T, L6 T5 y
  setup-patches
) d% e) N/ C! ]0 g  make-current one-of intersections
' J; |) X" Q8 d% d  label-current5 c3 P0 N; E4 @4 z2 x) }
* y! b" |9 a: U7 o
  set-default-shape turtles "car"
# T! o+ C, e! `9 G' E( T6 I# p6 u5 U2 I" z
  if (num-cars > count roads)
5 S, u# ~! V5 a! t! O; u  [
) Y. \7 \" k- I; O    user-message (word "There are too many cars for the amount of "
8 r8 M) R/ p$ b8 i                       "road.  Either increase the amount of roads "8 @* P. I, s2 O( S0 _& p) b+ V
                       "by increasing the GRID-SIZE-X or "( m" b8 w0 Q: J: Q
                       "GRID-SIZE-Y sliders, or decrease the "# O  [! L! R$ H4 W( [8 s% W
                       "number of cars by lowering the NUMBER slider.\n"/ C6 _3 H/ W( a
                       "The setup has stopped.")6 p2 Q) }3 w( {5 O$ L
    stop/ Z  Z; ?1 w0 i9 g3 ?1 C
  ]
# \* |1 w( `# C5 q
) f" s/ F3 r/ K3 Z6 z( Q: i" \2 m( `( Z  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* G8 J. K- U( Z% Q( Q. k  crt num-cars
2 G2 J5 Z0 Y5 d4 ^& N  h  [4 @8 d& q, j* R7 q2 D
    setup-cars
. i& D7 c& r2 b    set-car-color
' Z" x" y/ f' {3 C    record-data
9 h- @$ g+ j" y0 V  p6 M  ]
# K( }# O4 Y3 V9 Y8 e; S+ _. d4 `) S
  ;; give the turtles an initial speed
3 I/ g/ K8 a' H! E: L- e+ r  ask turtles [ set-car-speed ]
9 \9 }, Q( e2 k
+ C9 J2 ~. i4 G4 m6 C/ r  reset-ticks9 ]9 P0 Z6 Z3 G0 }& L+ L" A
end  @! Y4 B; ^+ _6 ?7 }
0 i2 |9 `, t; F: `4 @. q
;; Initialize the global variables to appropriate values. d- J! C8 q- X- L0 K
to setup-globals  j' @5 Q$ a7 \8 w% q) @1 k5 G
  set current-light nobody ;; just for now, since there are no lights yet8 y9 D# o( b1 r* l9 ]- {
  set phase 0
# O' m6 n) P9 [  set num-cars-stopped 0
, d. `1 }) a' I* d7 k. [$ p% g  set grid-x-inc world-width / grid-size-x
3 q0 M, p4 V- Y4 V& u' u  set grid-y-inc world-height / grid-size-y/ M2 M0 |% K8 A' u& f% R" P1 l
0 N3 c, Z, r+ `( H$ [" G
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 s" q; Y6 i% \6 U2 h( x  set acceleration 0.099
$ e9 I* k9 D6 ^end# t  z8 \+ O1 D% a, w* {2 t

0 K7 b3 d/ o6 _" V- ^, l$ f- f2 l;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 r2 n+ q2 W' O) w5 \
;; and initialize the traffic lights to one setting- J6 J- b) _7 E; Y
to setup-patches3 z& z( m  o6 c- b/ z5 o6 y% `& m0 X
  ;; initialize the patch-owned variables and color the patches to a base-color  v$ p# _* H# l
  ask patches
0 ^6 F% i0 S  R7 _1 J, T  [
0 N1 q+ [0 F5 b8 X* \    set intersection? false4 h# o9 S. @  V) J0 J
    set auto? false, p! X) V8 \" H% A- l+ v+ [) t: J9 ]
    set green-light-up? true! G/ G  a, a3 t# z+ j: K; f- g
    set my-row -1( [( ?( G0 u$ }# N; {
    set my-column -1
5 ]/ u% v& g" d$ o3 g8 m    set my-phase -1
0 y/ G5 a; z) ?# N/ H3 m+ p7 }    set pcolor brown + 3
/ T- g1 B1 P" f  T2 Y  ]
- T# }* G4 }. @2 H: _+ \7 U& I8 |$ e! ~& y8 T' q9 L
  ;; initialize the global variables that hold patch agentsets  W- {; x0 S8 E  E
  set roads patches with
* ?8 C7 O- r! y  j: s  w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or8 Z: r( u8 L- ~$ @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! y* W( ~8 S* o  set intersections roads with9 ?2 s# C3 f& z/ S( u" Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 O! [# _! O8 b  ]: B1 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% V8 V! f, @6 l" G! T
/ r9 J) q! W3 f0 B% g6 _" o8 U. l1 U
  ask roads [ set pcolor white ]
) K( r1 |8 j* A" k7 ]; ~    setup-intersections- i$ m( K$ E2 B* N
end+ K8 F5 e/ v7 N5 G
其中定义道路的句子,如下所示,是什么意思啊?
$ P2 Q3 g( D4 g set roads patches with
5 E* \! J. f0 K+ U: {- Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
' _5 Y6 }3 w* X$ y9 P% q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# \- g- n7 _* h3 C
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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