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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。
% v- D' [4 m7 jnetlogo自带的social science--traffic grid这一例子当中,
  i3 i- v0 R/ d( r4 q2 I3 tglobals
( X0 j3 i1 H' _, R[5 p( z- _1 X8 B- k% T
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" z! f& T+ E. g2 [3 _  grid-y-inc               ;; the amount of patches in between two roads in the y direction& T- S, B3 u2 S; u% m
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 U: ?  `5 i0 Q
                           ;; it is to accelerate or decelerate
% B% |2 G' m( n; i& M  phase                    ;; keeps track of the phase: s1 J( t, f# |5 v$ [' R, n* S+ U
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
, ^, H0 ?" K+ C! F/ k1 o8 ?  current-light            ;; the currently selected light
; |, d( y2 z2 L% n4 n% H
, j, v4 s! Y: H( i6 H  ;; patch agentsets
9 v4 j9 \0 _$ V  intersections ;; agentset containing the patches that are intersections: \+ J3 T9 s+ s, s
  roads         ;; agentset containing the patches that are roads
' y5 q. @" c1 X]
6 [* h; ^  \4 U5 j
4 {) c- j% b  L  Z' K  Q( A* c0 s' O- Kturtles-own
/ t9 b0 s4 Z3 v, J# e% t[
+ ~) I- ]1 h3 [  g8 L" g$ _  speed     ;; the speed of the turtle
4 O+ P3 _* Z' D. X! s; B  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ o1 u8 T, L, W! k6 O. k& i$ n% \
  wait-time ;; the amount of time since the last time a turtle has moved! _$ {$ s3 F0 o! {, N
]
5 C( z6 g$ f7 k8 @2 C  B3 G, U: P( q' g
patches-own6 b( T, [8 A5 G5 v! Q" E) Q
[
' s' o4 T/ l  ~, P  intersection?   ;; true if the patch is at the intersection of two roads( `" Y; K: Y- j% e4 @$ i
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 B- L- ]- e9 O3 P& o1 a# Y
                  ;; false for a non-intersection patches.; Y* ~* [5 n% D
  my-row          ;; the row of the intersection counting from the upper left corner of the
5 ]* {7 t  D+ A$ l! _- u( E3 s; Y) V                  ;; world.  -1 for non-intersection patches.
" A- e; H* D7 L8 ~  my-column       ;; the column of the intersection counting from the upper left corner of the
1 ?+ e, J" R* w: \1 _" p+ i                  ;; world.  -1 for non-intersection patches.
" @& F- R7 [8 x) F) q2 \  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' ?1 S# U& i: M- G/ K. j  auto?           ;; whether or not this intersection will switch automatically.
" P' j; [3 ~) z! T7 c9 I5 b! M                  ;; false for non-intersection patches.
# @9 S- U8 q# c# {7 C# t; V]
) j, K- y" p+ e) H1 }5 }
* O/ M5 M0 P) {/ q3 P: U
# }4 S6 E8 \7 X6 O  k3 ?. Z3 z! ]. e* N;;;;;;;;;;;;;;;;;;;;;;
- m/ |  b  X4 l9 ~/ L;; Setup Procedures ;;
$ z- {5 a: V) g, o) t/ ?9 V) {0 o$ U$ E;;;;;;;;;;;;;;;;;;;;;;4 C1 y- T& B8 C. _* ]" I
5 M' k) }/ j5 E) x- E9 U6 W
;; Initialize the display by giving the global and patch variables initial values.1 Q, U8 Z. w( h5 q3 D  [3 |6 B( h
;; Create num-cars of turtles if there are enough road patches for one turtle to1 p% E% @; s9 v$ ^' ]! l
;; be created per road patch. Set up the plots." D, i5 c  i9 `% v  f
to setup
+ w3 x% Q( _: z; b* E  ca% k6 E1 z6 v: b0 `
  setup-globals
  U! c& g6 o) p8 K4 |3 A* u1 G4 D, f( L
  ;; First we ask the patches to draw themselves and set up a few variables
& D0 x/ Z6 t6 V! B2 _( R  setup-patches/ q4 U. U* h# {  W. }3 L9 I4 x& O
  make-current one-of intersections
6 X: }4 ~. y+ T) q- {5 j- s, {  label-current5 m% o9 Y+ c# ^
5 V( u  o6 ~* T
  set-default-shape turtles "car"
7 W9 G9 e& b! O
8 c" A7 D+ \8 e5 r6 E# P  if (num-cars > count roads)/ \; n% f; ~. z* Q: z9 G! j
  [4 @7 e: t0 i/ A2 Q* ]
    user-message (word "There are too many cars for the amount of "
# [7 ?4 `, M+ F  d8 D8 @                       "road.  Either increase the amount of roads "# F7 |* p+ h/ C3 M- U
                       "by increasing the GRID-SIZE-X or "
7 k1 R" K/ u4 e7 p                       "GRID-SIZE-Y sliders, or decrease the "  \2 U# F4 d! r9 i; T; R
                       "number of cars by lowering the NUMBER slider.\n"
( r9 G: q) }  e+ c* f& A6 ~                       "The setup has stopped.")
% `- V9 u0 M$ }/ x    stop- e1 d8 Z  O+ l0 y! e
  ]1 ~" L3 Q0 {' ^" K$ k

( A% n3 C0 t. g: r8 @. d  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
& o, D/ s' U  a$ d* U, _7 E  crt num-cars6 G7 t$ `6 v* i  u: |, L& R
  [; G' q& E" [3 V5 s0 @
    setup-cars
; g5 X; O3 {# Q# T' y" m# ?    set-car-color
9 V3 ?% H* y$ S# _" C; ~    record-data3 O0 L4 z: T! q4 A/ }- z1 U
  ]
8 P# j4 i8 m2 D1 K: t( V3 q' N% X: l. Q/ g
  ;; give the turtles an initial speed
- U" w6 X& k" z3 F+ Z5 L4 v  ask turtles [ set-car-speed ]/ b0 ?9 F1 a. a% R3 ~8 B

3 P5 J, M0 T3 g" b6 X  reset-ticks
: S' Z5 ^9 B  u; s% _4 U) S, }end1 Y) t+ p  j1 r1 ~. k( |, V/ r
+ a7 X$ b! x" [8 y7 U+ t
;; Initialize the global variables to appropriate values0 |8 L) h& S8 u7 T1 o
to setup-globals
3 U9 l( S: d" P  y. \  set current-light nobody ;; just for now, since there are no lights yet
6 t; K, @: g8 \5 b* ]: K* w  set phase 0. o3 I0 d# j$ |/ @- F( M# H5 V9 F
  set num-cars-stopped 0) g% `# b; J2 j, Y6 a3 u5 N
  set grid-x-inc world-width / grid-size-x; c0 b. o6 E4 q
  set grid-y-inc world-height / grid-size-y
0 x/ `8 n3 C/ E/ g1 ?+ Z' `$ ?; |. j; y4 h# H- z/ n
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: J+ ~, D9 Y! Z% s$ z9 P
  set acceleration 0.099( ], k; }2 Z& t- C5 |% V
end) D! G# I7 h& u( s- E

, n1 R7 C8 x, ^% V. o: b" E2 ?;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ m0 v$ E. S9 _8 x/ j( N( H
;; and initialize the traffic lights to one setting
7 `9 D$ E6 h8 Oto setup-patches4 Y8 ^* i9 q4 j
  ;; initialize the patch-owned variables and color the patches to a base-color
9 [# i/ F* ?1 I" D: {  ask patches
+ O4 H) w8 g& T1 X  [$ N; n  G. ~% [& B0 R7 X% ^
    set intersection? false
8 R, E2 p; k8 T& ?    set auto? false
" D( Q) @8 N3 c9 w( R    set green-light-up? true& |& ~- K* M! `6 F, g- t  T9 W- q+ Q
    set my-row -1
2 \+ w- V+ p$ H: Q8 G    set my-column -1  t% f$ f9 {  U, p" S  g' ~
    set my-phase -15 M& r! s$ O; X% s; a* t" r
    set pcolor brown + 3
/ v  b( ~9 E: X3 e. r6 H  ]1 s3 @+ N7 @2 x# f8 {5 |: g0 l) l
/ O) x' O& V& }3 \
  ;; initialize the global variables that hold patch agentsets
4 B) E' l% u1 M8 U" l, P8 W  set roads patches with
  q/ s; d( h4 w! V9 i4 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 F1 V* K4 N! w( W! h! Z' N6 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 E; ^2 ~. n& k; J4 t& E9 Z  set intersections roads with
# L- P7 G$ @5 g; h; u2 s6 n    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, j) b; Q; H. n! ]) E) b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( T7 j4 M& f7 P: k2 z" q
; M9 r0 d- G3 H  G* n" z  ask roads [ set pcolor white ]
; A& ~( y2 |2 D$ J) x+ m    setup-intersections5 H7 K8 A& V8 F9 \, p( T# G
end. Z+ o9 W7 ?! W
其中定义道路的句子,如下所示,是什么意思啊?  g$ {0 y! z5 A) E. _  O
set roads patches with0 Z" w: L' P6 @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; I5 K$ z' A# b3 i+ Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& a, ~; I: {& y3 q: F9 k
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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