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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。
! b0 ?- o2 `7 Q7 A# Tnetlogo自带的social science--traffic grid这一例子当中,7 P8 u( l' ]# l7 C/ {5 a
globals/ h# n: ?1 D5 @6 `, O2 U7 Y
[
3 L4 t7 U' ]) D0 x; V  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 n* u$ n5 U4 O. h# y$ p  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ C% ~1 V. ]6 O$ S9 b5 m7 |; h& e3 v  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; y$ B- P8 Y* `                           ;; it is to accelerate or decelerate6 l8 G; h* |# o& {9 S' o# `, G2 A* x
  phase                    ;; keeps track of the phase
3 q/ j$ ?* j4 V6 G' k0 H+ H  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
3 L5 k2 l7 G6 K! |  current-light            ;; the currently selected light
3 J) v- u$ i% K; \, M
8 }, j- u8 S8 r( q/ J$ J) w. B  ;; patch agentsets
' p4 ?  x' C2 z6 D4 K! o  intersections ;; agentset containing the patches that are intersections. z: k- G5 x: ]: f) d
  roads         ;; agentset containing the patches that are roads
& g/ E' V4 q# r6 R" S' b]
$ y* |' Q' U- o- l! C: n" T0 V- Y9 b, b) o
turtles-own
5 L3 ?( J% J9 c7 g$ q- D[
* Q9 z9 e& i7 e2 M6 Z  speed     ;; the speed of the turtle
- o- K! c5 Z5 B% N. ?  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
  ~% V' M; Y5 ~. S- g1 _4 J  wait-time ;; the amount of time since the last time a turtle has moved( n, F" }4 b6 ^6 `7 f: K* u" q
]
% Q% p1 l3 G' C+ f* z
" c: i, Q8 W3 t3 vpatches-own
' m, Y2 m& D& z' r- [[. k) ^. A1 Z4 D3 t& U4 v0 i( H
  intersection?   ;; true if the patch is at the intersection of two roads+ S* J' f# R9 Y8 d  K9 D- J" k8 s
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.; A. z) W( {1 B% x9 v. N
                  ;; false for a non-intersection patches.
& H  I1 V/ h! E4 @! W4 P4 f3 X  my-row          ;; the row of the intersection counting from the upper left corner of the
2 T3 q$ p* ?/ y! E& ]- F+ r/ u                  ;; world.  -1 for non-intersection patches.8 @* u/ J; H6 c
  my-column       ;; the column of the intersection counting from the upper left corner of the
! _& d# j: c* b0 N% Z9 m5 g5 [                  ;; world.  -1 for non-intersection patches.1 P/ L4 |: ^- ~$ z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches., C+ v# s: E7 N0 O
  auto?           ;; whether or not this intersection will switch automatically.; t$ Y" S6 H6 P( u* t
                  ;; false for non-intersection patches.
0 h# @* Y1 A' C* k! z]! L. N8 n* p6 L$ f2 L$ ?9 H
, L1 M- A/ _) W$ |" y

$ g$ W' C" `( [;;;;;;;;;;;;;;;;;;;;;;
2 T; W, E8 r) J* @* h6 r1 G' S3 b;; Setup Procedures ;;
' B) z7 y, L+ z4 x. {;;;;;;;;;;;;;;;;;;;;;;
9 J: s; n' h  ]$ ^9 b: u8 ~! Q1 t8 Y2 m! s8 d1 P- m) Q/ H8 d
;; Initialize the display by giving the global and patch variables initial values.
* d& ]+ A. V. z6 q;; Create num-cars of turtles if there are enough road patches for one turtle to
  `% F, c) K" _1 v;; be created per road patch. Set up the plots.$ M; g* b0 [5 S' H, F
to setup# G' `) _. U. _+ l
  ca
3 v- M. `' K: Z5 [  A  setup-globals
' v. u+ W( y+ e2 ^% x7 f7 J. W1 _7 K$ H5 e# n
  ;; First we ask the patches to draw themselves and set up a few variables" P# D; T7 a6 y7 k6 k; N, N0 I
  setup-patches
! \- u5 l' z; ^: D/ _$ Y( L  make-current one-of intersections! v- i" _$ _, z  o* Y. L- c
  label-current0 t2 N  k' \/ O' E' p3 O
: F2 M" J" H- o) H* R. t8 j" |0 k
  set-default-shape turtles "car"+ p" a- N1 i* h5 \  J: K

* {( m) b* d5 K, ?8 |  if (num-cars > count roads)
% z! N. h- A7 A0 ~2 Z. z  [
, K6 O) u' Z" j. U: ~; d: u2 i2 K    user-message (word "There are too many cars for the amount of "5 P& n2 }  W7 m1 U- k$ K% n
                       "road.  Either increase the amount of roads "
/ o8 q8 f; U; L- l3 S. m7 C                       "by increasing the GRID-SIZE-X or "
& J4 W# i; {5 D8 b/ {! j                       "GRID-SIZE-Y sliders, or decrease the ": p% T! S" K4 f7 n/ s( ^
                       "number of cars by lowering the NUMBER slider.\n"- H! y8 p" Z$ f9 X2 r
                       "The setup has stopped.")8 k# w! s; U  H) N% D( h! ^- H
    stop
" y5 }) W8 t7 i* N, n  ]  ~5 k4 G0 O9 I, S* `( z
  P+ ]7 G" R2 t7 L- ?
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! j7 C" ~# H6 M# x
  crt num-cars
% x1 W* W  l/ U7 D1 _  n6 P. _7 k  [
/ }1 r7 ]! K" y4 d1 W: ^    setup-cars
" ^; [$ `8 N# ^* M' B1 M5 `    set-car-color: n# l5 C7 M: d; [% t
    record-data& @( t* W: E2 u/ ~- ~3 C" }
  ]
9 p, ?# r$ V  n5 `# b0 l: |
9 T: i) q# q3 }. v+ X2 H  ;; give the turtles an initial speed6 o( L8 f$ C, C6 P4 J* x$ B7 Y
  ask turtles [ set-car-speed ]7 V9 D& D. f: ]- }3 q* _
6 n  s' O& X* Q! U/ ?
  reset-ticks  a  j6 H, n! B* I5 u6 y
end: ?( N3 n1 G) ~: L  F

# X- x% o6 G2 E; |/ z) Q7 u( M;; Initialize the global variables to appropriate values7 }- s) @! \% F' @! r/ g
to setup-globals) P8 B# o- u2 S$ q6 E& A( O8 L
  set current-light nobody ;; just for now, since there are no lights yet
  P. O5 \2 z7 _! F$ _; w) l  set phase 0
- Z  j/ H# O' ]0 w; r; B  set num-cars-stopped 0+ D0 F+ n* x; x1 a3 _# O
  set grid-x-inc world-width / grid-size-x' m, t- |! d/ f( L/ Y4 o
  set grid-y-inc world-height / grid-size-y/ w4 a- r0 A, |9 v* ]# `

7 x( H! p; I% C7 {& k  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 f, v" m: ?( |4 g  B9 H8 Q
  set acceleration 0.0993 `1 c' ^. Z9 f$ `+ V$ I- [
end
/ L8 l7 e4 X  E4 q8 r' e. |
- D; @0 T( p/ [; c;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' ~- ]7 J* q" i$ i
;; and initialize the traffic lights to one setting4 ?% Z* X6 Q# }
to setup-patches/ H: h; n+ w: J# Y* A0 g  k: }
  ;; initialize the patch-owned variables and color the patches to a base-color3 M; c. n+ h2 Z; M1 t& I
  ask patches
  l6 {* C6 R4 S, L7 a. Y  [; L' W- p  M0 H- e3 ]8 r/ r1 e3 S2 q' x
    set intersection? false6 V' g# K9 ]4 W$ p6 B  f
    set auto? false
6 `9 l8 X* ~4 J+ I( d! J    set green-light-up? true: N" V, x' n: o' W" ?1 u/ ?. N4 U
    set my-row -1- P# X/ D7 `/ X
    set my-column -1$ T8 f, r1 b# E8 I. |( K
    set my-phase -1: V) Y0 D, V, Q( L* B& m! I  \, F
    set pcolor brown + 3
: K3 R+ q3 }, S: _( E, f+ b  ]: o3 ]. d0 B6 H0 X( H5 K

, A3 H) i9 ^$ P' T  ;; initialize the global variables that hold patch agentsets
$ J) K0 G6 z- I  set roads patches with& N9 {. t" Y% q' L* _6 S1 j& |# b0 a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 I, }3 T& d& G" w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* r. g! I  l; L. U
  set intersections roads with4 J4 z/ j) J" Q, m* F& t1 T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* {9 k2 n  S7 x: k/ Q+ u8 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 O, Y* D( j; a7 v( I3 X, m# Q$ Q

7 T, d6 f/ N9 I+ d4 T/ O& f  ask roads [ set pcolor white ]
3 q, _# p2 L. Q# M: V    setup-intersections" |' V: c3 q8 s! H
end9 j& }) O* v  }& j0 o) I
其中定义道路的句子,如下所示,是什么意思啊?
9 z9 |* q) s! `- R% t( X7 w set roads patches with
. q& K9 [1 z- {9 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 P6 F! s9 K: F# @( m    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 x8 b% B! m% C, v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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