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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。
1 R: c' j& G8 w& `netlogo自带的social science--traffic grid这一例子当中,
  S% F0 z! e1 T/ Y9 p0 K  \7 i' g( cglobals; W( _( N7 L5 R/ `" p5 u1 U
[
/ {1 d$ o! {8 q3 |' o1 H  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 m; _4 a/ O7 {+ B$ H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) e1 V5 K  z) @/ M  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
7 }$ m/ N5 i4 _- z- Z9 B5 |2 v                           ;; it is to accelerate or decelerate
: a3 _; L1 z/ A0 E& d  phase                    ;; keeps track of the phase0 z2 k# z/ V' D  I3 F6 }( k
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  Z/ S; R4 ]9 `) J. \" U
  current-light            ;; the currently selected light9 g! e8 z8 o" S( a$ o4 k
8 [  w1 g/ v2 |+ a# R
  ;; patch agentsets
6 V6 a  A8 }" ~' b" c' f0 M  intersections ;; agentset containing the patches that are intersections
* ^7 w" {* A7 w  roads         ;; agentset containing the patches that are roads3 L  j/ y5 ^* @( H
]9 c% D& f: [) }( o

3 _% Z( Z6 w  l7 Zturtles-own
5 y# i3 T+ T( @  H3 V0 Z[: b% S) m( k) y2 F( u1 |! z3 y
  speed     ;; the speed of the turtle4 r. U2 g9 o$ ]5 p6 y8 V4 T0 f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
4 T6 H6 ^  L1 K$ r( j' S3 a; ]  wait-time ;; the amount of time since the last time a turtle has moved' h* h/ d9 p8 v+ Q
]
. S; J* X0 q0 T* b
8 q7 ~" x7 f) W# u+ j' C  R$ upatches-own
7 `, r+ n# f) f* G/ y2 \& L[0 }+ O- q0 f7 g1 g5 @: j" Z5 P
  intersection?   ;; true if the patch is at the intersection of two roads2 c& V. D* T/ d+ t) W3 D0 C
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
7 u. A1 v" B* _% _& R& x                  ;; false for a non-intersection patches.
! `/ e- y7 n1 N9 `! n$ f  my-row          ;; the row of the intersection counting from the upper left corner of the+ t- `5 c2 v# u9 C
                  ;; world.  -1 for non-intersection patches.
4 f% r  M# w6 I# L) V1 p+ [4 G, N  my-column       ;; the column of the intersection counting from the upper left corner of the
1 q' E& c2 }- x/ x                  ;; world.  -1 for non-intersection patches.1 {( c2 ]5 n) t5 J& q5 p! D2 h
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.1 A) r# u' p, e* `7 y  d0 e- r  Z
  auto?           ;; whether or not this intersection will switch automatically.
  l  R1 I: P# \' t6 Q8 {                  ;; false for non-intersection patches.
* |, T8 j) q6 A& ~]
. z; N* I) o( m0 i8 ~
7 r6 Q+ l  k4 h4 Q
) W8 f/ F  V1 B7 ?; m, Q1 G/ O4 G;;;;;;;;;;;;;;;;;;;;;;+ G, O) v: k. Q3 s( }3 X
;; Setup Procedures ;;) q# m9 J, R) k; M& D
;;;;;;;;;;;;;;;;;;;;;;. w8 V/ B" d0 A$ N9 z2 J7 O0 m

8 v* e: F7 b- V! z; e;; Initialize the display by giving the global and patch variables initial values.
1 y. g8 \; f5 M8 m- j- ]7 O;; Create num-cars of turtles if there are enough road patches for one turtle to
8 J3 x. r) M- z: x# c;; be created per road patch. Set up the plots.
& g6 E$ ^5 c3 g3 q* E% Q% s' Dto setup7 M4 U$ S/ q- m/ A0 S6 U& ?
  ca8 s1 m% q& q$ s
  setup-globals2 [  S) {- |. X: k) f5 ]0 u& w8 ?! O# u
1 [/ U$ p: p7 s- B! ?
  ;; First we ask the patches to draw themselves and set up a few variables  d' M) o1 s+ u/ m6 `% e$ ~* z& T
  setup-patches  |7 l: c% e  S: ~$ k( ~
  make-current one-of intersections
* g3 p  |  m3 _# L8 T( Y' U7 }  label-current
) S( m  ?9 Q1 D+ y; A8 `
, d: d# `! U  X  set-default-shape turtles "car"' e' _7 }9 A; g8 P9 `, ]: q2 t

/ |; t# ^+ E4 j: `! E# T  if (num-cars > count roads)% y3 O9 M2 r4 Z6 s9 p/ U5 r1 a
  [, j2 [: R3 d' c
    user-message (word "There are too many cars for the amount of "
& f+ C& N* i( V$ q; N2 E; ?* ?- i( s  V& y                       "road.  Either increase the amount of roads "
1 n/ F. O7 G2 f                       "by increasing the GRID-SIZE-X or "
. d4 j/ ^2 a- o5 S5 \3 x: c                       "GRID-SIZE-Y sliders, or decrease the "/ r5 H6 ~! c( V3 n- a
                       "number of cars by lowering the NUMBER slider.\n"$ z: Y4 |+ T2 ]1 G7 L$ W
                       "The setup has stopped.")* z) e3 y& P. W  ?. ?5 U$ p
    stop7 V4 h) Q  z: c. i
  ]% N: M1 L) |5 b' i
. S' a( L# u6 u( ?4 |
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
$ Y0 {2 G" u. `( ^; z* ~- i% a1 ?  crt num-cars
) _) h% c* N3 ]" W  [
, z" {  M4 J! N0 Z4 l' S8 B9 ~    setup-cars  H  j4 M8 a2 i; J
    set-car-color
0 P2 u9 x: b9 ]    record-data4 `# H3 v( D" Q/ J0 S9 |* D
  ]# u: c! g+ h! M' Z
  ~: c4 @$ m: B! m; X" ^5 k- P
  ;; give the turtles an initial speed* b% n4 k+ q0 a2 V  W/ u7 G
  ask turtles [ set-car-speed ]& u. W. {+ o" K4 ~

* n( B. t/ v3 @  reset-ticks0 z, J& h6 `& b  b3 X
end: b) y# k. j& q8 S0 U1 c6 _

! ^+ N/ j1 X3 x3 ~+ y% B;; Initialize the global variables to appropriate values- O# A( s, K8 ^! s3 g
to setup-globals
0 j/ \1 ]* u: M. ~% w3 X  V4 B  set current-light nobody ;; just for now, since there are no lights yet. {1 Z3 z( f- j) u
  set phase 0
' q6 W5 ]: q4 c9 J$ A, P/ z5 k  set num-cars-stopped 0
( h1 a$ M- L# |$ c6 I- u% n  set grid-x-inc world-width / grid-size-x
  r" z, @' `9 Y6 I' w$ {' ^# M( M& y  set grid-y-inc world-height / grid-size-y
; ~+ o8 E5 U9 i( X) B0 C% E$ v# P+ `0 H  {
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 _( \$ X3 Q% |5 M
  set acceleration 0.099
& Z! u# I: Z& [: g8 S  K5 \end
" T( ?. n( T' y% c
, k! x' g$ N: ^, v. J- X6 x;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 E5 C. L9 t/ x* D8 @" c;; and initialize the traffic lights to one setting
8 H2 g8 [: F: r( j' H; p0 D: x7 zto setup-patches
6 c1 {+ b; F, Q  g% D3 [& A1 N  ;; initialize the patch-owned variables and color the patches to a base-color
) L& v  C0 j! P1 D6 j$ I& v  ask patches
2 \1 W$ M7 u8 n3 z  [
( D: K' W8 Y4 R# Q( F5 M8 m    set intersection? false
% A' V3 f  v$ b  a" o0 N    set auto? false7 K2 s* I  S) w! I
    set green-light-up? true
0 T1 n+ b3 e+ g- I7 }7 h) R    set my-row -1* d; a5 f9 q7 F; e
    set my-column -1
1 J; j. X6 h8 G9 g& u' A: _# v" m    set my-phase -1
! ?) H0 e  @4 f% n# t* T- H) ]    set pcolor brown + 3
& J1 R8 C2 ?9 b3 m/ X0 ^5 O7 C  ]: p. P; k2 }  ]: J4 s7 [% w% y
: K* j$ r% r, ^2 `3 g' k
  ;; initialize the global variables that hold patch agentsets
+ q- I9 L$ e0 ^& a4 q1 U( Z  set roads patches with
0 E: h8 w! c/ T4 ^) a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 E2 j7 I' A5 g" s4 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 D* h' O" ?( P/ d# S, G' H3 t
  set intersections roads with
* N' L, i. v) h1 \: B4 g' V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 m) u* l# Q" b+ [: }* o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ P, B# r/ _- J5 U  w
" }* i9 `/ P0 Z, N1 K, e9 Y  ask roads [ set pcolor white ]
& k0 F+ B9 C) u4 f, l+ G0 N    setup-intersections% f5 i) Q! W+ f) ?( j
end
4 O9 J  l0 B9 e$ ]( }8 N( b, I3 l其中定义道路的句子,如下所示,是什么意思啊?
5 Y: y  D7 Y) R set roads patches with
) C7 q: l! {7 a. {4 j& I! E0 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 B! P0 f. H' y5 O, z0 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ Y- u, d: K( r/ M' T: G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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