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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。$ Z) q5 X6 [. J- t, k$ l0 \+ v" v
netlogo自带的social science--traffic grid这一例子当中,
$ U8 L5 J& j1 l$ g9 s' H% {4 Kglobals
7 K/ b+ p! b' Q! ]( e) A8 q9 r[
+ ^! ?2 B  _) f/ E& S  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* y5 i+ Z) G- i! Q% K; m, f, F  t  grid-y-inc               ;; the amount of patches in between two roads in the y direction
9 V1 W0 b$ x# }3 I- |9 N* g" k  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ {' |* k9 R: D; }                           ;; it is to accelerate or decelerate7 M9 @7 v5 o8 D: Z9 {
  phase                    ;; keeps track of the phase
) `  j$ L! p. Z6 `  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure$ B+ k, _6 b* y( e) I
  current-light            ;; the currently selected light
1 i% j+ }4 Z0 t8 y2 M% k% ], f7 R8 Z1 P2 |& }% Q
  ;; patch agentsets
, \( h- s+ l4 w# ]  intersections ;; agentset containing the patches that are intersections
. |: {1 D/ o6 X/ u4 L" R! ]  roads         ;; agentset containing the patches that are roads
+ P$ r( Y9 |3 m3 z- N8 y3 o  c]
( y; d0 O. A/ P' u- z0 G8 D
+ [; `1 q% h2 `! Y) P4 Z4 cturtles-own$ h& E) M8 M6 F* ~8 a" x4 _& |& |& k
[
* y) @, s% t2 _" U  speed     ;; the speed of the turtle
, ~) i; m- L7 j  K. a6 W5 q  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; J( p. \. Q' I7 u2 ]
  wait-time ;; the amount of time since the last time a turtle has moved2 D1 x. P9 O) t
]
2 }/ [# ]7 x* O0 F$ m* K. }$ w5 ~& R% j0 y8 r5 h
patches-own; r/ {1 v7 ^8 Y+ W" X
[4 B2 R/ c( d( i  K$ ?
  intersection?   ;; true if the patch is at the intersection of two roads+ s+ b+ l/ A. i2 j% m" h) {8 ?& u- }
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.2 J2 X$ j& |  G1 q9 }( ?' u
                  ;; false for a non-intersection patches.
" Q- _( s8 B" B: A, q, t+ g8 l! I* w  my-row          ;; the row of the intersection counting from the upper left corner of the
. Z3 _! m" F7 l7 K                  ;; world.  -1 for non-intersection patches.
. E( u0 O/ B  ?, Q  my-column       ;; the column of the intersection counting from the upper left corner of the
$ `' ?: l! N5 v8 n# [                  ;; world.  -1 for non-intersection patches.: G4 m( m, c1 I' b/ M' K4 s
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% F9 N1 k) k& ]" z  auto?           ;; whether or not this intersection will switch automatically.
& \% m. |7 Z& W' J                  ;; false for non-intersection patches.* T6 b( v  a; f# E
]
( C; x0 I; V0 ~" O2 N" i1 U* z" D) F/ D# n" r
) g! j+ u- U) `& {
;;;;;;;;;;;;;;;;;;;;;;3 I6 H- I% _! g0 \5 z7 [5 T, e
;; Setup Procedures ;;
# p5 W; o7 c$ r. R% F" L;;;;;;;;;;;;;;;;;;;;;;* C  n- L4 |: |6 B9 M+ M1 ~* I( a
! F' F4 {2 b" V
;; Initialize the display by giving the global and patch variables initial values.
# [% l/ X5 _/ q6 Z;; Create num-cars of turtles if there are enough road patches for one turtle to
! |8 [$ x: r/ K* X' n: g;; be created per road patch. Set up the plots.
* v/ m2 a, C/ E% n) E( Q! Fto setup
3 k, K9 v3 s5 D$ @+ b7 R5 A* n  ca9 B/ M/ c7 _  h3 B
  setup-globals4 O% T( \" ~( G& ^) T% z$ {; ^
" S. j. |- F& _  D6 h& D2 r
  ;; First we ask the patches to draw themselves and set up a few variables) n! _% ^$ _% R/ b, X
  setup-patches
/ r: {4 v2 U0 i+ Y. W$ Y  make-current one-of intersections
" X& K  i! c4 F; `  U$ p) l1 F  label-current: |( Y& p/ ]  j: ?' ]0 V/ O$ B
1 o5 n- t. v2 t7 p5 f
  set-default-shape turtles "car"
; r# k% U/ b1 g' R
' H0 n: d) D1 {9 n9 c, j) M) W! l9 m  if (num-cars > count roads)7 t5 n& o+ f- s  G
  [: u( K; O! P; b8 Y0 @. r
    user-message (word "There are too many cars for the amount of "
) `% A2 f- l- g% s% e                       "road.  Either increase the amount of roads "
/ k; O1 W( t' e  h$ v4 E                       "by increasing the GRID-SIZE-X or "
  K+ ?2 ?( d# V. g+ T                       "GRID-SIZE-Y sliders, or decrease the "
  c, C/ h2 U6 i  U                       "number of cars by lowering the NUMBER slider.\n", n8 T! s4 j% g1 k  Q+ V, n: N
                       "The setup has stopped.")
( _9 X. x3 C" H3 b9 d) s$ g% i- L    stop
2 u# P  t+ K6 |2 j+ Z  ]% s; e0 d8 R9 R8 \- F! M3 L& U
/ t' K& b8 @6 F9 T) K  g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 Y+ B4 x# [4 d. u7 g  crt num-cars
3 N( v$ W, f: a  [( l, J9 F! k- H& E+ k$ s
    setup-cars
5 x( ?, ?# p/ a8 t3 w- X2 M    set-car-color* Q+ S  K" f9 P* Y: e- G
    record-data; }/ v# f8 s' N6 R/ W% R
  ]
! [8 s) n& u; ?' V% ~# v, d* k8 w# u) V3 ^: z; M% e  U# u( O( o" o9 ]; @
  ;; give the turtles an initial speed0 `- g/ s: E9 a7 q6 Q3 |
  ask turtles [ set-car-speed ]: M* f! a8 w. O& \2 _  b8 {0 r

! v" X: ^2 h+ {& {" \% J: w1 r  reset-ticks% s; A' w2 }' e! W$ I4 k
end
( L1 A: y$ \: n" k0 r' D; S$ x
# `/ }; c4 N* o;; Initialize the global variables to appropriate values
6 Y% E6 w+ s- N# f6 ato setup-globals
) e7 o8 B; q$ @" B, c  set current-light nobody ;; just for now, since there are no lights yet# }9 |* `1 {4 |& d0 D$ S
  set phase 09 v3 x' M; a% d
  set num-cars-stopped 0
9 T# [8 `4 j: |0 s2 ^  r  set grid-x-inc world-width / grid-size-x$ b0 e  Q1 a3 f1 |* c+ T
  set grid-y-inc world-height / grid-size-y# L/ \+ f/ p- v% H/ Y* K4 F
5 j9 c) V( M2 v- O( A# P" C
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: g9 K+ P, z% Q5 D" r: T5 K  set acceleration 0.099
% e% u3 r2 E0 V# T, R; r+ o+ fend; Y9 T9 @, C1 |7 _

# Y! \4 h0 t  u) a5 |;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
( o$ n1 u5 c: @# M, t1 E;; and initialize the traffic lights to one setting* L1 g' j! B) @) A: s$ _  t3 R
to setup-patches* G: G% B- r9 l" Y
  ;; initialize the patch-owned variables and color the patches to a base-color
/ h0 x9 i9 S9 f6 T4 z. L9 [  ask patches
* R8 b3 E) g# q7 N/ p: s  [
8 y/ Y* M; ^. F0 ?2 n# {( z    set intersection? false
+ Z/ b0 d6 n+ i% X) |; P    set auto? false
' M" c2 i' G* Q$ S    set green-light-up? true
9 N% o0 d- m% e/ W    set my-row -1
$ {& a; K0 W( Q0 P( x% c    set my-column -17 E' v: j& J. t8 `( o
    set my-phase -1
7 U" ~. l# I! Z! h0 q    set pcolor brown + 3
, y4 i/ d' S0 f- ~6 O/ u  ]
# ]. U% F6 Z9 ~7 L  M
& @6 _+ v% B5 K1 l) g# `  ;; initialize the global variables that hold patch agentsets: ~& t2 ^1 P+ n, w7 M
  set roads patches with* w  y1 r- X& C0 \. K6 z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 F; w3 i8 e2 o5 R9 H3 _# k+ G: q  x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' `- T2 g& r3 d  set intersections roads with
0 d% N6 A4 ]9 H3 |7 k( y3 _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 k, a$ W3 v6 A9 b- o' B' p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 x7 K2 _! Q7 Q9 w1 c" v( \$ w+ d* Q+ D5 D
  ask roads [ set pcolor white ]
  C1 a/ w5 S3 t% L# _  T- W    setup-intersections
) D4 u; O4 l2 F$ Z- e8 u" v( S/ ]end
7 ?; S2 W9 r( B. E' ]7 p其中定义道路的句子,如下所示,是什么意思啊?9 [2 a; O7 o! o- t' G- `6 s8 W/ X
set roads patches with
& b2 R4 X) J6 @' C( q+ h, |# M# i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or4 r: u/ E0 g, U3 K- Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], G4 `. @$ ~2 c
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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