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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。+ a" i0 X& v0 k( b
netlogo自带的social science--traffic grid这一例子当中,% Y/ ^# W# e% ]' z
globals
" J% Q% h/ d  g6 p9 C$ Q& [' J[
0 x+ k7 D( u1 [4 |  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* }/ O% y1 g; n  grid-y-inc               ;; the amount of patches in between two roads in the y direction
0 E0 l6 I2 G* T" n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ p4 G/ r8 ~- [                           ;; it is to accelerate or decelerate% w3 O1 ]" w9 F! d) }" T+ S* T
  phase                    ;; keeps track of the phase
9 l( j' N6 c! A+ i# B$ R  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, Z$ J+ y: H  J, z. {" N, {6 m
  current-light            ;; the currently selected light! }1 w, X5 T! B

* c- ?: X, ]1 t' w* P: [; Q  ;; patch agentsets* x- G0 X; ]$ j7 u7 ^. n! F+ i+ e+ K
  intersections ;; agentset containing the patches that are intersections
) }! C7 F( h3 ?8 k' q$ q0 V/ ]* z  roads         ;; agentset containing the patches that are roads1 |; {1 X1 N! M; x
]0 f9 H+ d3 k8 O. ?

8 q, i, U0 X3 q' A" zturtles-own
, r) c9 ~- c) K7 T. r7 F- v[
! H/ j, u3 G5 A, Z  speed     ;; the speed of the turtle9 e5 V4 p, {/ \# m7 b$ K* q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right2 t' P% w8 Y5 F7 s0 g! p; t! Z
  wait-time ;; the amount of time since the last time a turtle has moved
! r2 B3 {3 }% C' q# t, q]& x: g4 O* u+ _9 K& F
. o! C$ j/ s( f+ O! a/ R7 {) f
patches-own
4 _6 i) ~; F7 {9 |5 W[  a" T( {+ k) w5 f3 G
  intersection?   ;; true if the patch is at the intersection of two roads0 g7 E% F- S" \- b) u
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! o  T" l  h8 n' C$ j                  ;; false for a non-intersection patches.
5 h. N6 @2 R: z5 f  my-row          ;; the row of the intersection counting from the upper left corner of the
5 n: G% }0 u. w  m" k( v, f                  ;; world.  -1 for non-intersection patches.
$ @- ]7 z* E! E- ]5 B) R  my-column       ;; the column of the intersection counting from the upper left corner of the7 {2 v$ B8 c6 `& t2 d
                  ;; world.  -1 for non-intersection patches.# N" e" X( p; ^9 H# k% D) ^
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
$ s; N* n$ I$ v5 t8 G; T  auto?           ;; whether or not this intersection will switch automatically.4 \' s9 _" [) |2 [2 q) r1 L
                  ;; false for non-intersection patches.
$ o' \4 ?& {; `' M]2 X" A- L  ?8 L  B0 Z  n4 i
0 S# R2 ?$ U2 v6 V5 a# T; S
+ o; j+ `7 Y- s2 i1 S6 X7 ^6 f
;;;;;;;;;;;;;;;;;;;;;;
. y% u, b( \. x0 z( b; N3 y;; Setup Procedures ;;
5 M% g7 t& I) `, i4 `+ P) M( A5 q;;;;;;;;;;;;;;;;;;;;;;
# P( [' p  P5 M  K0 s: ~+ w4 r8 z7 B7 K  Q) W" i* ^; Y. n0 w
;; Initialize the display by giving the global and patch variables initial values.9 v8 I9 {7 Q% ~) }4 G
;; Create num-cars of turtles if there are enough road patches for one turtle to+ |7 ]& q% i" s" L8 ^9 k1 G( d( }
;; be created per road patch. Set up the plots.
9 v3 m$ J3 o! C$ mto setup: L4 ]- r8 M. ?
  ca
" K' @( z  s( q9 A( o  setup-globals& P3 h1 H; {) V) ]' o

7 \& j/ U. n" ~& g* D  ;; First we ask the patches to draw themselves and set up a few variables( y& q8 w; v3 o: z+ r% l" g3 d: I
  setup-patches3 C7 C2 B7 u$ x/ b* ?( e4 E
  make-current one-of intersections+ k' T, z+ F0 L+ X; K
  label-current
- ~: k2 q4 M+ ?3 L8 d% \- E
. k& a4 F% k* N* T" d  set-default-shape turtles "car"
; }) @8 T8 |- c  k# U# d; d
) ?/ \+ `$ e5 o% e! r  if (num-cars > count roads)8 f+ Q4 C6 i( f  m5 @: |
  [0 K( R- z! Y2 M) O7 A
    user-message (word "There are too many cars for the amount of "% L! @* a9 s2 P6 v
                       "road.  Either increase the amount of roads "
2 s' {3 f6 {3 ]3 M7 [4 U  S                       "by increasing the GRID-SIZE-X or "
) G" Y" J, k- `4 S0 A( ?9 _* s/ [                       "GRID-SIZE-Y sliders, or decrease the "" F, C5 l1 j. @+ M
                       "number of cars by lowering the NUMBER slider.\n"" I4 r! w- N. e" a, q
                       "The setup has stopped.")7 @! e3 M  ]" P' m, l3 a4 j
    stop9 ]5 U: l0 r6 \/ H5 q: b
  ]! N4 ~; }, v. ?; }' d
9 k; g1 N2 \( t5 X' h3 j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  Z2 E% h  @0 M8 r% y) I1 M
  crt num-cars5 p. A1 G4 Z" N0 g! n( c
  [4 b, V  l+ H* p" m1 i5 i
    setup-cars4 h' y( n) j  Y# U: r
    set-car-color7 h( n; |! U2 c2 j: C7 q. x; E1 t! @
    record-data4 C; v1 l& I, m
  ]0 g/ ^, w3 q9 k$ R
1 o) R% [0 b4 V$ ]) w, ^+ g9 |5 L2 a
  ;; give the turtles an initial speed& n5 E0 s- v( x8 ?
  ask turtles [ set-car-speed ]! c/ g8 M3 p' Z
. U" X, V' f# }0 u. L* [% X; w
  reset-ticks0 H! @" y1 O6 {9 x  J/ {# Y
end( ~+ H4 R- r2 [' _* ^
! X5 U2 C1 [, ], N, z4 w
;; Initialize the global variables to appropriate values$ W  K  p9 U1 h+ o( e. y" t- ~
to setup-globals; l  W) |$ ^4 C/ `! p
  set current-light nobody ;; just for now, since there are no lights yet2 D# E6 w* H! ]+ O( L
  set phase 0# P+ w& c1 h, ]! q
  set num-cars-stopped 04 J( k0 a4 e  |
  set grid-x-inc world-width / grid-size-x
, ]* `* B+ ?8 r6 C* r9 U  set grid-y-inc world-height / grid-size-y
' X7 w& v* ^1 R# M* {2 B: g1 B: F$ `( w( L, C' s7 k+ I
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
  j! S" {) g7 H  set acceleration 0.099& @6 }  t# C; M! P
end# d9 H5 S6 T- X0 t9 U: d
, f& j1 e& X3 w+ n0 p% Q8 U$ ?
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
+ i; I4 @- c: A$ S, [: X. e  p- F;; and initialize the traffic lights to one setting* e2 ]' J8 m6 o, f* d8 L# o7 d
to setup-patches7 I7 e* ]$ ~5 G; }! w- \/ K
  ;; initialize the patch-owned variables and color the patches to a base-color% w6 R+ M- M3 Y! R" d
  ask patches
+ j, [# R" M( S: G# c  [6 W0 Q5 A8 N; M/ q1 ]/ T
    set intersection? false" Q" a% Y5 o  B) U' v$ m1 a/ o
    set auto? false
1 \0 z& z/ V7 b/ \$ f* r    set green-light-up? true; t+ j# P, x5 F; I
    set my-row -16 Y1 i6 B4 y6 [+ G/ ^+ I4 S6 _2 v9 F8 ^
    set my-column -1* v( K! w* q2 A: |* {+ w, n
    set my-phase -1
, @/ j2 T  }! k" b$ ^) F3 O7 {0 Q    set pcolor brown + 33 g& U, f3 O+ N  e
  ]" J. S- z7 ?' [6 a. L+ ?8 g4 X5 }( j

% z1 e% U. ?# x" j# D: o  ;; initialize the global variables that hold patch agentsets2 P: e( g+ s9 n
  set roads patches with
' P( J( s9 z  C2 a4 U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
+ h- s9 W: A' J! w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 u$ T- m2 u5 e2 b! m" c  set intersections roads with
* G9 y5 Q- c/ e5 {0 R; {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 S% k. P6 W, Z, @% s! P8 n
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 S4 S3 Y$ w7 Z2 V' o7 D; x) f. F* w' @& S1 w' j) j
  ask roads [ set pcolor white ]
4 f8 m4 I1 V! N7 I    setup-intersections! M0 [3 U( D$ D4 N& L
end3 |) t, e+ p- ?, p' a/ u- w8 s
其中定义道路的句子,如下所示,是什么意思啊?
' J3 A* L+ |& n' f: S" a. L. a set roads patches with
- `* a5 O  J7 I2 @5 G    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 w  w! H2 b+ N5 e+ o8 D* ?" g3 Q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, f! G/ B0 I, S; \% Y: A8 {/ ~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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