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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。
4 m% l/ O5 N8 q3 h( D* q0 lnetlogo自带的social science--traffic grid这一例子当中,8 \0 C0 u& E: N4 \3 K
globals
  V7 A' j3 c+ P9 M[; d7 W" v) p' m1 Y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction# @; \' k$ C- B& \- d
  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 ~  i" s; `9 x6 N% V. Y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, X' b0 s+ I: e$ v9 d                           ;; it is to accelerate or decelerate8 \% K' C. F6 H' {7 k; d. T# g+ ]
  phase                    ;; keeps track of the phase' [4 C' `5 j! Z; e/ C" j4 G
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 y* D: m/ B4 s1 V: \3 X- ?2 O; ?  current-light            ;; the currently selected light
3 {6 w+ m3 ^" A8 U9 g9 g: c9 ?0 U& p8 |
7 J) q8 y0 @' H4 k  ;; patch agentsets; E; k. \$ ^& N) i. S$ G
  intersections ;; agentset containing the patches that are intersections, |% i: e# z/ C0 y  t" j4 J
  roads         ;; agentset containing the patches that are roads4 u+ R! P8 R& x' s" ~% _
]
- r3 I" T: ~" C7 R' H# U
# ]1 J4 i# Y9 @# gturtles-own7 S; B$ w9 U0 I8 E
[1 h" Q; Z- s" L" ]" V! U  j5 l: b
  speed     ;; the speed of the turtle7 U4 M( ~6 q. B8 t  f! |$ n
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: S4 e% U; Z- ^  wait-time ;; the amount of time since the last time a turtle has moved" F8 S1 F. S* G' @( `, ?
]
: h9 Q2 j; W; }: D. v% o; a
3 S. y* Z* f6 N2 J' g( f/ Xpatches-own! z) V/ Z; S, Z0 q
[% @$ v' h9 t, v
  intersection?   ;; true if the patch is at the intersection of two roads
6 c5 j5 l) I$ J0 B. s+ I6 H  R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.3 b9 N/ O* o% t" u- |' |1 Q. N  C/ v
                  ;; false for a non-intersection patches.
& A8 T& R1 o1 B; J& H  my-row          ;; the row of the intersection counting from the upper left corner of the1 B# c+ R/ D4 A; r) L8 u; a
                  ;; world.  -1 for non-intersection patches.+ J5 c  l2 g8 I- S) H8 B
  my-column       ;; the column of the intersection counting from the upper left corner of the
. x2 _) s# f* `3 i, Q                  ;; world.  -1 for non-intersection patches.
4 C0 H  g" N* S! C" R3 U: T9 q) g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 j% X  \6 A4 V" L
  auto?           ;; whether or not this intersection will switch automatically.
( S0 B, c$ Y; M; F' n( |                  ;; false for non-intersection patches.. g3 ~; ?5 r1 q* r5 a
]$ L& p8 r2 T6 ?6 ^  w; r- A

9 `/ @, g! ?; u; k
% s/ q; v' Y, M# o* r* _) T. z;;;;;;;;;;;;;;;;;;;;;;
% U5 M9 }: h4 s0 l8 u;; Setup Procedures ;;, z) z" H9 V+ a
;;;;;;;;;;;;;;;;;;;;;;
+ ?* y4 W) \! @+ s4 p* q2 q
3 B/ X' M  r7 g" K( l;; Initialize the display by giving the global and patch variables initial values.7 d( m$ S) E6 S! K7 f4 E
;; Create num-cars of turtles if there are enough road patches for one turtle to
4 T8 k' Z2 Z+ l. Z: ?% [;; be created per road patch. Set up the plots.+ }( M0 a7 M% p
to setup0 \; Y/ |/ t' D3 \* c, z
  ca' P! o7 |+ i. y  n  N- G. U
  setup-globals
% m7 ^. {4 {' u% l) Y! ?: l3 `  b& I. r3 }& j+ o' m
  ;; First we ask the patches to draw themselves and set up a few variables& w- `7 N5 R4 [* \1 K' {- X
  setup-patches
" U+ i+ d4 _; X& H2 L7 ]% o  make-current one-of intersections. s2 q5 M/ L/ [$ U, T% r
  label-current& L% |  B6 v* R7 Y- }9 g

  `9 i! i2 [8 P6 Q  set-default-shape turtles "car"
6 V+ }& d; t7 [8 _
2 G8 O& \+ w5 K1 A2 D  if (num-cars > count roads)
( b: {8 a( }2 ^9 G" \5 a* B  [
9 [# w' ^! o6 t1 g    user-message (word "There are too many cars for the amount of "/ s! X9 u% O9 g7 ?
                       "road.  Either increase the amount of roads "
& x6 r, W6 c# }4 l# s5 Q5 ~                       "by increasing the GRID-SIZE-X or ") u9 @3 @3 I% ^( b# _7 I
                       "GRID-SIZE-Y sliders, or decrease the "* K4 u& b* C' |( B+ u; }
                       "number of cars by lowering the NUMBER slider.\n"" F" ^$ N# G8 X  {
                       "The setup has stopped.")
5 z# Q$ b3 s2 j$ H6 `% d4 c- v    stop" R! D% ~7 J4 t1 I
  ]
5 I3 ?1 y$ O  z  Y" h( p1 y, @6 G1 p  b
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 J! [1 p# j  D0 Z( t, U+ X
  crt num-cars
& L$ E3 t9 u' P# C1 t3 l  [5 d& z; z( i& A: l; X& P+ E. X& A  q) ~
    setup-cars2 q1 a+ }: z5 m& ^6 S  W
    set-car-color& N8 ]& U6 X( B
    record-data
& g* m/ M+ y: [) J" M0 @" Z  ]# M* k/ x* b& o3 z! F7 ?

9 h+ i* a/ U* D  ;; give the turtles an initial speed
* Z  y# f* \# ]  ask turtles [ set-car-speed ]) M0 v; s  W3 p

( N0 ~9 C; q7 L3 S6 o" |7 a5 F  reset-ticks$ A' u5 ?  ~: V& e$ u$ ~0 L  P! @
end( Z2 E7 i7 V* R

4 M/ c1 {5 z9 z' g! I;; Initialize the global variables to appropriate values
& J$ k' u( h  Uto setup-globals
; _. B7 N* R, j1 ~3 a6 f0 h  set current-light nobody ;; just for now, since there are no lights yet
1 B& E8 c# w% X0 E) T+ _; Y  set phase 01 H/ C- ^. l$ }7 C
  set num-cars-stopped 0* s* \; y: p- C( G* w" v0 N
  set grid-x-inc world-width / grid-size-x
. J$ F  g2 b+ ^  set grid-y-inc world-height / grid-size-y
) d4 l1 K8 e2 Z! D) _' P' y* P5 w0 N/ k
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary: B& G2 L/ {, V8 L1 h/ a
  set acceleration 0.099. I5 T- V! S. f& ^7 P( o7 |0 D
end
7 O- q! ]2 H3 Q4 p; P* a* E
% Q) Z2 n* t+ ?; M4 a;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
9 I" r- k) {  }% X9 t- O0 {;; and initialize the traffic lights to one setting
* Q: H+ V( ]* k& y$ \: L( Ito setup-patches3 w2 Z2 ^3 A# W$ j! F3 J
  ;; initialize the patch-owned variables and color the patches to a base-color
) i6 q* d1 v3 h3 P  ask patches
2 H0 o' Y: D6 N% f  p* }  [
" y% E+ C" M, |    set intersection? false8 w1 ]/ y7 L0 E" Z/ i- n
    set auto? false/ t& P0 C+ Y0 [0 b" ?) N
    set green-light-up? true
& I( k' t; b: z7 k    set my-row -12 L+ Z$ O9 G  ^2 [! f2 V
    set my-column -1
+ P' Q' x" Q( s, \2 P" E* l    set my-phase -1
& b$ k; g# W  c, W    set pcolor brown + 3
/ [% Z" d/ ~5 ^  ]
: V* ^# D1 F; K& [
& i1 Q$ Y' C! X8 g  ;; initialize the global variables that hold patch agentsets5 B% X3 c* b7 ~' T: I# x
  set roads patches with% X' W9 L- w" ?" o  F) e; W6 G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 S/ c8 g0 _( d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& @- _1 {2 r: F1 l/ V- Y9 ^9 B  set intersections roads with
3 |+ {/ I5 C% H; c; n: S* I! W& s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. e2 q, o# t' h3 k: l1 D4 _+ L( ^8 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ ?$ F7 S, j/ G/ r% ?' q) M2 Y' W' e& D- a6 a: x, K6 X1 l4 B/ z
  ask roads [ set pcolor white ]. k. q4 F0 @- I2 R- m0 @
    setup-intersections8 q) m8 Q/ S, j! y) {0 Y) |2 n
end7 ~" a) u" O0 |9 x
其中定义道路的句子,如下所示,是什么意思啊?
( Y6 D6 C: Q1 O9 R+ c8 P( f set roads patches with
5 N! z7 C  K+ S  \3 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! _# l$ s  a$ p  g2 R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* j; X& T6 V/ [- p, L
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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