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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。- \# Z  G* g( \/ ^7 `  t$ w: R
netlogo自带的social science--traffic grid这一例子当中,
. [! U* @9 V6 D; gglobals
7 O/ q% g# Z! K* s7 S[
& m6 e0 S3 ^8 m: }1 ~/ b* k+ c  grid-x-inc               ;; the amount of patches in between two roads in the x direction, ]* l! S$ z! B" F
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, _! C) m4 q# b" M: q. Z  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. D3 A1 U' `0 C; I! X                           ;; it is to accelerate or decelerate1 X- x  u* Y# m: j, c
  phase                    ;; keeps track of the phase
/ o- i9 q, a# r  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure6 y7 w4 h* d  Y, M7 h
  current-light            ;; the currently selected light
( a$ Z$ Q: q8 V2 N* o
3 c1 D% }+ W, v+ G  ;; patch agentsets
* Q: q7 x( d- m  \. A% a  intersections ;; agentset containing the patches that are intersections
% H! f  p4 u- q: m0 w, m0 y* t  roads         ;; agentset containing the patches that are roads
& p; T; u) P& y( k& m]
" X) a1 a- ]2 \# ~9 W6 D
' s4 i" g" b3 x* xturtles-own
% c1 X; J( Q: X+ \& _8 N5 G6 V1 U[7 F" |) ?1 R: C: X5 X! A9 r, u' ^
  speed     ;; the speed of the turtle
$ x) R+ G2 l, H5 n* ]9 M9 w. U# f  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ U3 U' y6 M9 ~5 `  x0 f  wait-time ;; the amount of time since the last time a turtle has moved  h  b0 a& ~8 ~' n) y5 U
]& m+ V9 U" a' I2 ]2 S& U8 H

8 w. z1 ~7 _; h9 _patches-own
- w. {# A6 J- l0 q- p1 o[' n6 k+ y/ R& ~  y  W
  intersection?   ;; true if the patch is at the intersection of two roads4 R) J- a4 Y8 f$ B9 C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
3 d0 ]# @9 V. L8 ^- h- b                  ;; false for a non-intersection patches.0 K; `6 b# |, m- R0 W3 ?& f
  my-row          ;; the row of the intersection counting from the upper left corner of the
$ y/ c1 E& F8 E" t2 x; y- N                  ;; world.  -1 for non-intersection patches.* r( }. @, w1 H7 \. O
  my-column       ;; the column of the intersection counting from the upper left corner of the' ]- w( m/ l+ `# S$ C4 @: g, b0 s& E
                  ;; world.  -1 for non-intersection patches.
, D; m# _! s+ {7 G/ D+ _: g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  ~, C& v4 a4 V/ \9 f
  auto?           ;; whether or not this intersection will switch automatically.% n, ]5 h+ \9 [4 `3 L
                  ;; false for non-intersection patches.2 g8 i$ _. W! }% l" {
]4 I: l# ?2 D+ S4 t5 r# r
' Y# G* l: A% ~: w

, z9 M" n1 z" F. h1 V8 L$ };;;;;;;;;;;;;;;;;;;;;;
# X( D5 `/ Q& {4 ];; Setup Procedures ;;; I2 A" m" [9 m) u
;;;;;;;;;;;;;;;;;;;;;;
% \- a9 b; o$ {7 Q- [- W
; g- ?9 Y5 T: T9 p& u& k;; Initialize the display by giving the global and patch variables initial values.3 V+ t  B7 w/ Q2 y. `
;; Create num-cars of turtles if there are enough road patches for one turtle to" [+ G1 g( j. V* t$ D3 z. I6 Z. q
;; be created per road patch. Set up the plots.3 Y1 `& K$ S. O+ H3 N
to setup
2 l6 R- c8 R4 S! d% `  ca' ^$ U6 g# X6 k5 c
  setup-globals) A: w+ H5 `9 N& O1 m. J4 L" X' f6 H
" |- U" t$ _9 ^1 z; h& d
  ;; First we ask the patches to draw themselves and set up a few variables' s( V& q$ `; ?: @) `/ C
  setup-patches1 T* e/ o- q' P, y9 L7 R
  make-current one-of intersections2 }2 G' p7 u* d- i* I( J  u4 b
  label-current, Y7 O: Y9 ^7 d2 F
; r. k: C* h6 A3 |; E; T
  set-default-shape turtles "car"
: ?3 Y0 G; h+ T8 h3 h0 o' m& R8 Z% ^0 ]) k0 p2 h
  if (num-cars > count roads)
# A( f9 Y( y  j" j  V% f* n, A, Z  [
7 @6 q' L4 [  y2 @; J/ r    user-message (word "There are too many cars for the amount of "- _# G* |/ z+ \, ?- o
                       "road.  Either increase the amount of roads "* Y) P) B* J0 {. F4 B) e6 \+ l
                       "by increasing the GRID-SIZE-X or ". s' C0 N/ ?* Q2 J# k& l
                       "GRID-SIZE-Y sliders, or decrease the "5 Z5 p7 F& R4 @9 I# |
                       "number of cars by lowering the NUMBER slider.\n"
7 o; S0 R' {7 C  {6 T                       "The setup has stopped.")( g# g/ o+ R% n* y6 ~. ^7 {  m
    stop: `! K/ |- k% D3 C2 m: `! F3 k
  ]
# v; G9 c. U+ Z! M- b0 {- r0 w8 H: {+ d; O% K* R% r  m$ Z2 u, J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( i! g* e# o8 K# E9 M7 {  crt num-cars; V* E5 `% {7 f" d
  [
- s5 `8 q$ W# H1 b    setup-cars8 n3 ^$ S0 Z& T) B! M
    set-car-color
4 S' x' P( x/ i. n, q/ K    record-data
. Q" w  ~( u# }/ K; n% f  ]
3 X4 e, I! ?' m1 n% [
$ d% i/ v. G5 t1 `2 `  ;; give the turtles an initial speed
7 c1 ^/ y4 T/ ^  w1 w' x  ask turtles [ set-car-speed ]
! G, n+ l5 M4 ]' m* k! `7 _
$ }6 e, B" o4 |5 N( n) Y4 {  reset-ticks' ?3 E$ H* v( v2 {+ ~" M" s5 _
end
# ]$ }" x# ~0 D3 k% k6 Q8 |4 w% f, _
;; Initialize the global variables to appropriate values
/ r: ]7 z- s7 _, r" @to setup-globals
% P6 ?$ v5 v: {- }0 n4 Q  h  set current-light nobody ;; just for now, since there are no lights yet
4 z0 z: D# Z6 j  set phase 0
/ g; v4 \0 h: \! G, Z6 ~3 Z  set num-cars-stopped 0
) J+ t5 j: j! H- M  set grid-x-inc world-width / grid-size-x
" A" x0 c1 L3 a  set grid-y-inc world-height / grid-size-y
& L3 E. p0 ^5 s
, V" C/ E# T  U* _5 b  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, K5 V# W  S& o9 Y
  set acceleration 0.099
7 @$ a+ e6 i) p5 a5 \4 W! cend& U% T% L5 {1 \2 |

( }) t  {, S6 H  }4 `. O;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- T& V$ ], x4 F' u0 L# [9 h  Z
;; and initialize the traffic lights to one setting
9 m/ t5 b7 E  [3 ^# L7 Yto setup-patches7 C. T4 f# r$ B4 ~8 E" }& ~& }
  ;; initialize the patch-owned variables and color the patches to a base-color' r8 ^$ @' H8 \# o/ A3 I
  ask patches
: C" `6 r2 v2 t) }  U  [
1 D+ q( T1 i& x+ I1 ~( b; M* _    set intersection? false8 |0 F2 T) D3 ?4 J$ D- [  v
    set auto? false4 X. U0 W" n/ L! l" M4 r4 y
    set green-light-up? true/ T2 o, L$ y$ Z' m5 D( X, v
    set my-row -1
. C* C3 N& E" T4 n( {    set my-column -1
) m: ]0 S' D/ I! s. f0 H7 J    set my-phase -14 z! N, g9 }& L, a
    set pcolor brown + 38 ~- o8 A% \8 s1 g
  ]
. K0 z1 g; W- P$ {# f( k, ~* Y, V& V5 G1 X* b" P
  ;; initialize the global variables that hold patch agentsets; d, E; d4 S+ u5 q+ H" f
  set roads patches with
- |" [  R8 T$ n2 t% V" g. y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) ?% a/ [0 Q" D3 ^" j7 R# A' i1 a1 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( I! Q4 ]3 W' J9 v3 L- F) x4 |
  set intersections roads with6 K7 D5 d4 F( j! J' t  ?# E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, T+ w  |. _5 x, w7 G4 Z: @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 l5 q7 s5 l8 G5 D) [
7 h6 z1 d/ q$ F  ask roads [ set pcolor white ]
  _' g* P5 k( A; n( t% N% M    setup-intersections1 \6 n! q  n4 J0 q
end& Y& Z( ~' z/ Q' v# W$ T
其中定义道路的句子,如下所示,是什么意思啊?2 v" G# V; N) }" l  r, I
set roads patches with; G4 p6 F9 {) M# F5 C, R# u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) h) m$ ~- u; ]8 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) g) b) w9 ?: @+ R8 L: j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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