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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 D" B9 Y5 Z! @4 u, l
netlogo自带的social science--traffic grid这一例子当中,7 p% M# ~3 x. m1 J1 G
globals
# G& _! D" e/ V[% @5 `6 f  j, l( m: S0 L5 ~
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ q* q& ]: Z, i/ R" W6 |! t  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, ?' {  P1 o( v) {  k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
! ]/ S& a. @) y3 D; z                           ;; it is to accelerate or decelerate0 \2 ?8 ?; k. v6 \2 x2 @. o
  phase                    ;; keeps track of the phase5 Q1 [' `( z. L% t
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 l7 k+ C- r3 {, y& z  current-light            ;; the currently selected light
1 k+ g- o, E7 O3 m( u3 W/ Z% N& n/ |9 U
2 o/ x/ J& u! N4 {2 j2 m  ;; patch agentsets
8 I; n5 t0 a: G: Q* d6 z* U3 i' B/ i  intersections ;; agentset containing the patches that are intersections% o! ?9 V/ c& D% w* J: m% W1 V
  roads         ;; agentset containing the patches that are roads! _) P3 e8 W- e1 A' Q8 `
]
7 q* _/ i9 L( O  s
4 h* P8 ~# a9 Uturtles-own% |3 T- ?" R* h5 J+ P2 p
[3 {4 N* S( B* C6 u5 {
  speed     ;; the speed of the turtle3 U6 \: Y9 A1 ?2 L# n) K/ W
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right8 v* L# b% h) c
  wait-time ;; the amount of time since the last time a turtle has moved2 j3 [) R& a/ R  l  i
]; Z7 r7 g" N9 T: |! ]9 L+ o- ]
/ C! ~5 `* o8 \" f+ {, k! A
patches-own0 K& f7 B2 o+ }5 ~1 C, M! {* M
[" {' l' Q' W( @4 U# _  k# n
  intersection?   ;; true if the patch is at the intersection of two roads0 m% t6 R" l4 A7 V8 L" H; r5 o! E
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
) f5 n( p) V5 z) |- m: D                  ;; false for a non-intersection patches.2 N7 o( J! L  j  j! y- t& e
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 f  s' g* R; _6 U! _                  ;; world.  -1 for non-intersection patches.$ R! w+ f2 R. }+ J$ d; q% }+ t
  my-column       ;; the column of the intersection counting from the upper left corner of the" p( ~. Q( _  `+ n% u
                  ;; world.  -1 for non-intersection patches.
" N. d% j  R- ~( H# I) B/ s  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" k) b5 a9 _, q  auto?           ;; whether or not this intersection will switch automatically.6 X2 Z/ _! N) C2 n9 U
                  ;; false for non-intersection patches.; K' z2 G5 ~* M; ?0 o8 |, z
]
/ R7 w% u, f/ f/ _5 e* a, m
% v  Y8 j5 P" F* W. ~" g- X2 L! J: L7 f
;;;;;;;;;;;;;;;;;;;;;;
" }% A% F0 }- h2 Z  v8 [% A* h;; Setup Procedures ;;1 X( Q. \1 p+ T9 M/ g: ~! o. k, @! m
;;;;;;;;;;;;;;;;;;;;;;; f8 p* A, _- D$ L. Q

0 B/ f; p/ p1 s, x! i;; Initialize the display by giving the global and patch variables initial values.
: I, t& T6 X* Q- o$ T, v;; Create num-cars of turtles if there are enough road patches for one turtle to# E1 T- w' [/ q* E; j5 x
;; be created per road patch. Set up the plots.4 U& C; v+ z# L# [. S
to setup# l% |  d7 D( h4 `6 z& {( i2 W, ?4 W  o
  ca! v- ]+ @7 }) k' @/ N
  setup-globals& P+ k. {$ f0 t4 r1 B* l8 ~8 }7 m. Q

" Y# Y: L) j1 Q% g1 N* [4 N  ;; First we ask the patches to draw themselves and set up a few variables
* B9 Q* ~% g2 Y; z) E6 \  ^7 F  setup-patches
; t. u0 F7 N$ p8 X* M  make-current one-of intersections
" N7 M) P/ o, F' v  label-current$ O1 E& D1 C& I

! y. `& K% U' D" \3 H  set-default-shape turtles "car") a5 u# W) I; C9 H  _3 @

7 |9 @. R+ x( p$ a( S  M; W  if (num-cars > count roads)- T! D4 u) B, I; q4 t$ e
  [
* j2 l% u: Y- ]  y4 e$ B    user-message (word "There are too many cars for the amount of "0 y& I$ I) b3 R, i# V8 ]  y
                       "road.  Either increase the amount of roads "
3 G8 Q' F/ z7 |% @: u                       "by increasing the GRID-SIZE-X or "0 X4 o. w3 |  |
                       "GRID-SIZE-Y sliders, or decrease the "
+ y" s9 v( f7 {                       "number of cars by lowering the NUMBER slider.\n"* `$ g; t/ [+ z
                       "The setup has stopped.")- ^% y" V1 S/ {! J* F8 ~+ ~- X2 P
    stop
" q( n8 P6 u( {$ F% F  ]
5 C9 B8 w- h' r% N8 Q6 Z& S  `# p/ `! d/ s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! T$ f# J& \( S' x- ]5 |  crt num-cars6 [0 Z: F, u3 l9 p2 ^, [/ n/ ~
  [
# m$ H  p" S1 {( @    setup-cars
0 u2 p# T" @: b1 ?) h+ S, l' N. t* ]    set-car-color
1 j9 N) O2 f1 o( p# t1 z    record-data
9 G/ B3 b0 i' l6 J/ H  ]
  K7 P$ q2 m; m( n1 M. x# B9 B; U9 R9 [
; W6 J, p, A/ P/ i4 N2 I  ;; give the turtles an initial speed4 b" o6 U" e5 K+ j, G6 ]$ y
  ask turtles [ set-car-speed ]
2 {- r: N9 X; ~; l8 v. O  h
/ K  |/ n* n+ V2 }+ Y( x- W, Q' v  reset-ticks
* G# E; N2 r# o* [1 X  ~" l4 ^end" z  z2 |) z3 M$ Q! x1 g" V) v9 Z/ O
% p0 P% E3 o8 N& m( w; @9 k
;; Initialize the global variables to appropriate values, l. s0 U9 G. j9 h% T( ?
to setup-globals
3 l" j- G$ c5 H" A  set current-light nobody ;; just for now, since there are no lights yet7 R0 V, o: g' \- J
  set phase 0" U+ P* }" F7 i1 i5 e' g0 u# u
  set num-cars-stopped 05 L( _  J. V9 ~& N) h3 I
  set grid-x-inc world-width / grid-size-x3 _# r) `1 `5 ]2 \
  set grid-y-inc world-height / grid-size-y
- F5 |9 j/ |) u' [/ T
* B4 S. i9 m- |  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 I) y1 }  E* y: ]$ P  set acceleration 0.0993 g) N  A) W- {& x
end
. s/ r: Z2 n- i$ h) f! o7 z. _6 A8 N+ Y5 L8 t$ C! C
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,: G0 Y$ ?& t9 T- M( @
;; and initialize the traffic lights to one setting7 B- H& ?8 V/ u3 [! ]& D& |
to setup-patches/ k# @. \: C! |1 E
  ;; initialize the patch-owned variables and color the patches to a base-color
- N$ h( B! P" x0 M& k1 d+ W  ask patches
, i5 P- v2 t2 h" a& d: s9 s' z  [
& ^& N6 b1 o; V2 a    set intersection? false8 l( h4 A+ r3 F% T+ k$ r+ T* @$ i
    set auto? false
8 F( }8 m9 {7 [, e  U2 a    set green-light-up? true: n/ w, Y: E( B- w' Q4 L) T/ l
    set my-row -1
0 o0 B: d6 Z; y" D    set my-column -1
9 C/ o6 B, x9 B. Z" L+ Q5 l    set my-phase -1
- Q0 B2 q5 ]) U& A7 B  |+ A# U0 p    set pcolor brown + 36 U5 s. u9 [, Q
  ]- Q3 G1 t0 _/ e3 n  _* _
9 p9 ~# t0 y+ f  ^  s7 s
  ;; initialize the global variables that hold patch agentsets
5 K6 Z# ?3 R( ]9 T  set roads patches with2 e! G1 U( q: ]* I3 Z+ u: B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" r. w9 @- Z" w# t. d& D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 A4 I" _0 f3 E5 L  set intersections roads with
, \* @/ T$ E5 |& \! d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 N" \, W: E$ n& q* `/ c4 l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 ]; ^- P3 F# q3 N5 W, M( m2 ?* Y$ A' a$ o# r
  ask roads [ set pcolor white ]
7 ?, i3 S- W+ ^& @% c  b* x    setup-intersections( J! `8 a* s' {7 Y8 D
end
: L7 [4 K) S( A% k  }- t  `其中定义道路的句子,如下所示,是什么意思啊?1 S/ I' n) X- u4 Q5 I
set roads patches with: F4 \$ A6 D/ L6 [! l9 D0 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& e; }5 c5 I( x- z0 v- ]
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 t8 w9 T  _% i$ y2 q2 {. s, 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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