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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。; N* J" v; T8 z! E: v+ u
netlogo自带的social science--traffic grid这一例子当中,
& M2 k5 x( Z7 f" X+ L" oglobals
) i, [: C5 X& N/ H, |[
4 ]0 @# p1 u2 [1 \, Z( t" Y1 S  grid-x-inc               ;; the amount of patches in between two roads in the x direction( }. b! H$ h( |6 o
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. e' x  b# J* @& @' ~+ Y9 Y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 B6 T- f' ~/ [
                           ;; it is to accelerate or decelerate
. B6 t2 S; g* i3 b# a2 ?- `  phase                    ;; keeps track of the phase, |) A" ^- T2 J8 N- Q# c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 h. j1 Y* [5 w6 ^0 o- u
  current-light            ;; the currently selected light8 j! c+ y4 W. X2 ?+ S3 q5 T
1 ?; e" W1 B+ y( T: v8 U" R' J+ s: d
  ;; patch agentsets
7 g6 I6 K! }& b! `: a9 t  intersections ;; agentset containing the patches that are intersections* i' ^3 m% T: @( j& n0 m7 X9 _, o
  roads         ;; agentset containing the patches that are roads
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, ^* p- l8 ^' ^! E! U. W* I. e4 J4 M, Q: D
turtles-own
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  speed     ;; the speed of the turtle! w2 o2 Q5 L! t/ b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' l4 c5 O# a6 v* I9 A  wait-time ;; the amount of time since the last time a turtle has moved0 h7 O! l+ e  d: W/ J4 H' s
]
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patches-own
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6 Q5 J$ \; j  n* k) H  intersection?   ;; true if the patch is at the intersection of two roads2 i+ ~$ K0 d. M
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.7 d3 C9 ]9 f$ U! W  p, x) ^
                  ;; false for a non-intersection patches.
- B+ B4 [( W# M- i: b  my-row          ;; the row of the intersection counting from the upper left corner of the5 c' @3 X2 H% n- u0 q- G
                  ;; world.  -1 for non-intersection patches.
- E6 C; W% U" d( X( H  my-column       ;; the column of the intersection counting from the upper left corner of the
/ S2 W8 F! Q7 U5 M                  ;; world.  -1 for non-intersection patches., [5 X$ ?" J4 I; I" d' a$ v3 Q# O
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& i0 i; E1 }2 b& a8 D* l& f
  auto?           ;; whether or not this intersection will switch automatically.
1 v# N: w7 y0 Z+ v# O5 p" F                  ;; false for non-intersection patches.
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/ F1 l" r6 P& ?9 f$ `8 @* v. T  h( G( l7 v- \; ?- y
;;;;;;;;;;;;;;;;;;;;;;% Z1 |; O8 f/ `9 K
;; Setup Procedures ;;
: B( o8 Y: j+ \, B;;;;;;;;;;;;;;;;;;;;;;$ d& F( W0 _6 Z8 ]( P
0 C$ p8 N8 G7 K8 S1 Q
;; Initialize the display by giving the global and patch variables initial values.
& T5 g# C! c0 R' ]- O! h;; Create num-cars of turtles if there are enough road patches for one turtle to6 F  G4 T8 w$ K5 }' r/ d
;; be created per road patch. Set up the plots.
  H: [7 K& a* g/ b: B) U" Vto setup2 I5 K0 j8 s& v8 x0 N% G
  ca  _# K+ o! i9 W- g: d
  setup-globals4 p! \$ t1 {0 \2 X1 @! \
  S% B- ]( k6 f
  ;; First we ask the patches to draw themselves and set up a few variables
$ w' g- C. b0 J2 G  setup-patches, @" k4 ^' m, g# {
  make-current one-of intersections. ~5 s8 J& E# N$ Y
  label-current$ G* D4 v0 S, M4 @' n8 d" ?5 j
- A$ O7 A! j: Q
  set-default-shape turtles "car"
% c  K' o" J4 u8 F7 `/ v0 b) j9 x. g6 y! h7 O8 v. \
  if (num-cars > count roads)
" X! u" ?& J0 r' [! W2 N4 |  K+ ?  [9 J+ w" I/ s  s  ^
    user-message (word "There are too many cars for the amount of "/ D" n4 }" w5 U4 e
                       "road.  Either increase the amount of roads "$ v1 d" w' L/ ^" n. }/ J
                       "by increasing the GRID-SIZE-X or "
" A' N) t' O7 h: R) @0 ^5 h                       "GRID-SIZE-Y sliders, or decrease the ", C; _& `: b& P+ d3 F6 \8 b
                       "number of cars by lowering the NUMBER slider.\n"
( z3 H7 c' Z" G- s: S; o6 K, Y                       "The setup has stopped.")
  l9 F# t' Z$ O& Y! D$ S8 E9 J0 M    stop
$ c, l$ Z5 K1 c  ]
2 f  I6 H  c8 M! D% U2 K/ ?0 ^9 T$ }& V
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* R4 p1 g- ^8 _/ J  crt num-cars) G2 A0 j0 o4 h& C+ o
  [$ y, ~6 q/ O1 a( Y
    setup-cars; y% `5 w; C8 ~7 \! y7 l8 d& s2 _$ B
    set-car-color
9 m' v. ?. m( a& K/ @    record-data
6 d! w5 \# t% H% ^3 D  ]+ n9 E3 V2 H' q$ P
5 F4 r7 k# A- s9 b
  ;; give the turtles an initial speed
8 j9 Q: f! ?+ j$ z; u  ask turtles [ set-car-speed ]
5 |" h" H5 L& V9 K( k7 {" d" A. G' D! m
  reset-ticks
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;; Initialize the global variables to appropriate values
3 w8 M5 v6 A& S' r3 H1 Mto setup-globals
& I! N/ b, {7 R4 h( ~/ r% D. h  set current-light nobody ;; just for now, since there are no lights yet
. e) A, ?9 v! |; W: n1 @  set phase 00 _# U/ A! _/ F
  set num-cars-stopped 0: b3 h# t" k* I" P
  set grid-x-inc world-width / grid-size-x
, Z! N+ A+ @0 i+ Q, ?% x. b$ A  set grid-y-inc world-height / grid-size-y/ M. ?+ W3 T4 t0 j% \
4 q4 `4 j0 s' S2 h& b# K) Z* X) S
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' a6 ^  t( X9 E0 p  k) d  set acceleration 0.099
" ^0 {1 Q7 T+ x5 r8 z2 H1 I9 Hend
2 N0 g& r3 c) f. @* S$ f9 g
$ g& `+ v' T) ^/ r. u0 M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* o0 k' V! f' C1 E5 X
;; and initialize the traffic lights to one setting3 s! y+ o' T5 H  X! Q/ h
to setup-patches
  s4 [0 z. ?/ ^' B; v7 u8 ]2 j9 I; K  ;; initialize the patch-owned variables and color the patches to a base-color
9 X$ b3 o* \  `3 o  l$ }- S# {  ask patches/ a/ f; @  D! F( k4 z5 I4 d; U
  [
; I: v* h6 Z4 s, M    set intersection? false
- a5 n' `2 `6 w$ K' u    set auto? false2 C$ U% [# ^; B0 n8 [/ f$ ~8 B
    set green-light-up? true" h$ E# v3 O# D( r# ]  a9 E1 ^9 f% m
    set my-row -1( m8 t4 h0 o; e3 A% b7 k
    set my-column -1) s* I7 p4 V) c4 O$ T# V- M
    set my-phase -1
" \0 J- E0 T  I    set pcolor brown + 3
( }, Y9 T& J' Q2 B6 K& T  ]
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+ T9 r  O* t/ u" @1 d  |  D3 q* @' s  ;; initialize the global variables that hold patch agentsets3 f0 Z% v: j" [. C- R
  set roads patches with% {' ?% U; j; O5 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 t7 T- t" C7 W
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' V" v$ f2 z( }; L8 p3 h) O
  set intersections roads with+ v. e8 w! M! f  N  ~/ U) e. C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and: m- T% L) X% f$ _4 g. `+ i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
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. i8 u$ L. ^5 ^( y2 L; w- k  ask roads [ set pcolor white ]
/ a) N/ p; p* Y0 M. F    setup-intersections
8 g) _1 T6 ]  P+ A/ hend
7 D7 v* Z- ^' G/ j5 l2 n其中定义道路的句子,如下所示,是什么意思啊?# w+ ?' O. L* F, E
set roads patches with
' X% Y( b: ]9 p4 k" p' u2 H, _% ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ W+ n% X& Y1 c; K+ \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  q* Z4 X0 J, D  I8 ]
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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