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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。
3 `4 p) ~8 X: O$ ?3 `( Qnetlogo自带的social science--traffic grid这一例子当中,: N% G2 p+ i  U$ z7 x
globals: v; m$ b: v! \
[8 d% }- h# a5 G( l2 D5 V) K
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
' D4 {9 O' h7 G+ C) q8 u2 C9 C& ?  grid-y-inc               ;; the amount of patches in between two roads in the y direction# |4 @- s. F* j) }' s& D' y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& ^) V! X# x. D/ R( v                           ;; it is to accelerate or decelerate
5 ]& d0 c% i( _( L9 h! B# h: |  x  phase                    ;; keeps track of the phase. `% ~% T- L0 t4 X+ @
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% ]' |6 W* ]+ Y/ o! e  current-light            ;; the currently selected light* e  V/ G, `+ z- V* Y& E% R/ ]: ~! ]! z

' `  \+ T, D, @8 V7 s$ a& v1 @) N  ;; patch agentsets
+ N8 |1 ]+ j/ A( q$ s  intersections ;; agentset containing the patches that are intersections
) a0 F  K, P# N! m; l8 F  roads         ;; agentset containing the patches that are roads
) E) P: d2 v; Z$ u" G]
. f- T& s% ?% ]8 r$ n
3 }; b! m8 X( o' n/ c5 Dturtles-own
) e0 R2 Z4 X+ J% `! e8 j# I[
1 _: o& b7 f3 w4 b1 D  speed     ;; the speed of the turtle
) R% ~2 D# H7 I  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( q0 B' ]9 @+ p, O% ^7 C4 z  wait-time ;; the amount of time since the last time a turtle has moved0 X! h' ^, i4 w; y/ ^7 U* h
]3 K  v* w& ~! |* f0 K. M
- V2 c. c! ~2 g6 [& E, x
patches-own
% S9 @& b+ A9 c( Z) N, N[7 @: T8 O1 r$ n; ^- L; Q' d/ u
  intersection?   ;; true if the patch is at the intersection of two roads
0 @3 j- D! {1 ~! o8 R; D; d1 o  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. P, q* B8 w& ]3 Q" R9 {
                  ;; false for a non-intersection patches.- y7 P* v! J/ |) I$ |* `/ _
  my-row          ;; the row of the intersection counting from the upper left corner of the
! J, a% ^5 G6 F2 D# l8 y; n* y/ ~1 v                  ;; world.  -1 for non-intersection patches.- r  N9 q1 G" E! o" C3 ?# R
  my-column       ;; the column of the intersection counting from the upper left corner of the
* O$ M9 }9 v6 s! ^                  ;; world.  -1 for non-intersection patches.1 W' x$ ]2 D* G9 ^' a  V  q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 ]% ^! ^+ k; l; _- C6 z1 S3 d8 N  auto?           ;; whether or not this intersection will switch automatically.
1 Z; A) {6 ?; d# E+ ]; f( p                  ;; false for non-intersection patches.- b) K: C$ a0 e  X
]
- K, ?8 J" |2 I; I. D
  |& \3 z! X7 G; W, _) j6 f8 U8 \% n5 b6 h
;;;;;;;;;;;;;;;;;;;;;;
9 ?+ B/ ]$ q) B. ^+ v;; Setup Procedures ;;+ ~) \8 {- m2 c0 a4 x6 J" h* @
;;;;;;;;;;;;;;;;;;;;;;  V; I- c, [( E& A, D

5 i9 C% d, Z: n; A+ {;; Initialize the display by giving the global and patch variables initial values.& o( z! t3 s5 ^. m9 O: f3 r
;; Create num-cars of turtles if there are enough road patches for one turtle to
, i( o+ t- |; ~. p;; be created per road patch. Set up the plots.7 o. F% L# y* x( |
to setup
* e8 Z) \( ^- M0 L& \" X& z! r: B4 ]* j  ca5 M; @$ z/ N" Q" h3 O( [1 d1 w
  setup-globals( H8 I& N! B, t5 o

2 z5 y& t, A8 E/ i9 a& j5 l  ;; First we ask the patches to draw themselves and set up a few variables2 ^: T. P5 _( N( d. ]
  setup-patches- B$ R# P# E, S" c" F- E
  make-current one-of intersections
3 A7 P/ S* x7 ~- v( {8 L, |. z  label-current4 b0 Y- i. \! o+ p8 v
$ }& N4 i8 N  r. G1 {: u) z
  set-default-shape turtles "car"9 ^% E! h; k. a

/ b) r2 [/ l9 H0 a  if (num-cars > count roads)2 i  A4 v5 P4 Z& r, Q
  [
) G! B8 b+ [6 n4 r, n    user-message (word "There are too many cars for the amount of "
! q$ J/ N8 d; u- I; {0 O7 _                       "road.  Either increase the amount of roads "
. T% E1 h: Z* T; _0 B                       "by increasing the GRID-SIZE-X or "3 ^$ {7 n' B) |( n" _
                       "GRID-SIZE-Y sliders, or decrease the "3 I0 T$ ^+ u' I* e+ Q; j, c7 [
                       "number of cars by lowering the NUMBER slider.\n"
3 `# }2 {, d0 w# E; L$ N- H) w& d* m4 m                       "The setup has stopped.")2 C& ]. J8 K4 ]5 I9 D8 R
    stop
+ n# R% u/ E. F3 I  ]$ t7 D' }" y+ [0 S# ?+ n- H7 L0 g1 z

, U! P) v  a( d: n2 C0 W: ?2 i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! {) ~6 q3 O- c8 S1 X  crt num-cars+ }; v4 I4 I7 {" Q, {
  [3 u2 z: j& t* H3 _, T
    setup-cars# Y1 p* \  J, ?; Z. D  A. U# D% P
    set-car-color% N1 L0 a5 {% C
    record-data
' d7 p( y8 A7 _* @7 D" `. N% k  ]4 O+ O+ b$ {: p

+ {$ Z, O" Z" }" M/ k2 ]  ;; give the turtles an initial speed
: H/ ^4 b, J$ n  t* B' ?  ask turtles [ set-car-speed ]7 ^& L& O7 a. u1 |7 n) Y5 f

) _; m9 }  X! [- K" P4 T  reset-ticks4 g3 h3 n) @& k: @9 x' }+ M. ~
end
# O* l. l  A- }. O( z" U+ Z( A/ d/ I7 N) D
;; Initialize the global variables to appropriate values2 ?; X7 m" F1 c5 H4 T2 Q& ?
to setup-globals& @! e% z4 ~" _7 i' B: S3 t
  set current-light nobody ;; just for now, since there are no lights yet
1 v% Q; D" g# F4 P  set phase 0
$ k# }/ t5 X( r  set num-cars-stopped 0- X- L- d9 R0 U' n
  set grid-x-inc world-width / grid-size-x
1 \& h3 ?+ L! N0 W! |  set grid-y-inc world-height / grid-size-y% W! G2 ]# ]# ]* |

, B+ ?, P8 s. R0 P8 }7 I% Z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% G7 y; ?( g: t8 Y4 G1 F% w  set acceleration 0.0991 a+ b3 C% p9 p+ l6 t  K0 B' c3 a
end
" C" p) b4 n( o1 E% P% {) ~6 z# D0 }
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
- P# B6 L) N! k1 Q- a( s! U) y: N;; and initialize the traffic lights to one setting. H( U8 C1 O  `9 B" G
to setup-patches
+ y8 v3 G* T8 J) Z  Z; I  b/ M  ;; initialize the patch-owned variables and color the patches to a base-color$ m$ d' L" Q) L# w% ]6 T+ Y. X; ~" h1 E
  ask patches6 ^' l# O! ?& k* z+ E) n
  [
4 J2 V5 U" k/ S0 X: n    set intersection? false
! ]9 J! R# K6 q2 ]! u    set auto? false
: O2 A' G1 P* Z& R0 B4 l    set green-light-up? true& s5 t' y* D2 T- y
    set my-row -11 W: K: A8 P7 a7 |" |; d2 k! L
    set my-column -1+ e, }" E) |) H3 D6 B4 j6 Y4 }
    set my-phase -1" X5 n  V# \& g8 N
    set pcolor brown + 3
$ t" ]' V( }9 g' k- m  l* a3 F" I  ]
! J1 y/ g, ?& o7 y
+ d. a- M9 ^: U/ [2 q8 C7 z  ;; initialize the global variables that hold patch agentsets
+ p: K( U) T4 _" A2 F  set roads patches with/ _7 H# _* K# N3 Z3 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) u, l5 c' D3 F7 \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 E8 h  k& _7 a  set intersections roads with
0 b  J2 S/ {$ e    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
' e  Q, H) A' V1 x1 v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 ]& f& k" ~6 y7 N$ J) \1 N

- t9 x2 h# i- i( E& D1 v0 f3 G4 ^  ask roads [ set pcolor white ]
: i, A, W4 U  q; O9 t; K$ y! b" l" V    setup-intersections
! a" c' M# z% ]/ Uend. y$ [; N0 T, U# r6 P; r
其中定义道路的句子,如下所示,是什么意思啊?3 r& m) o8 @2 g0 c" p$ d
set roads patches with
! N; R7 v  A9 M, i$ k) f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 q- f0 O4 k; q% Y    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 m- `" C0 f: o
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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