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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。8 p' M  i: Q$ P: Q
netlogo自带的social science--traffic grid这一例子当中,7 W8 p! T+ c2 _( c. U, I
globals1 ?9 C, ~9 r$ W8 N/ p! f
[) F, t- f# w$ E
  grid-x-inc               ;; the amount of patches in between two roads in the x direction% C% E# N# s( v- u% m& }. `( i
  grid-y-inc               ;; the amount of patches in between two roads in the y direction& @8 K, `2 N3 k0 g( V+ W2 x0 z3 r2 c
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: m7 ?7 y( ]; g% K" v3 t
                           ;; it is to accelerate or decelerate
# r2 p/ L6 B" w, n1 @/ r8 a( ?  phase                    ;; keeps track of the phase
% p/ ~8 s8 T; }0 Z) N  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% J3 y" D; _9 U& F1 [  current-light            ;; the currently selected light9 u1 f0 [' d% V
1 t7 ]- I4 S' K. w  ]
  ;; patch agentsets
, R& o" Y8 w2 I4 J4 ?. r7 w( K  intersections ;; agentset containing the patches that are intersections* Q$ A/ n6 Y  m" Z6 K% H
  roads         ;; agentset containing the patches that are roads
7 i$ q* s2 H7 D0 U3 u]
2 j3 o: z; O# p/ u4 d! _, F4 V/ N: Y( [* R4 {/ ?- Y5 N
turtles-own$ _8 T, R3 G2 L: f1 e- T" b; T  f
[
/ c7 T3 O$ t" ]  @7 _: f: W& P2 a  speed     ;; the speed of the turtle
8 H! o6 v" q8 ~+ n5 U( ]: h* ]  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
- U3 ~- B" M1 G" ?9 J* y  C6 i  wait-time ;; the amount of time since the last time a turtle has moved
  e1 ]6 l9 Z6 O# N1 t9 ^]$ h! k, @$ C: V( `
6 T& p6 O; v$ h' l/ y- \
patches-own$ U' Y  C) @& O, a5 E3 X& d* `) G
[
+ B8 U; t9 u$ @" {$ Q3 t  intersection?   ;; true if the patch is at the intersection of two roads
: X0 y$ d) s% [8 R  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- `* S& R1 s3 {4 v# k+ `                  ;; false for a non-intersection patches.
; \6 Q- r1 f( K6 b& ?% m% ]( |0 n  my-row          ;; the row of the intersection counting from the upper left corner of the2 J  G2 @8 X3 U& D/ g& c
                  ;; world.  -1 for non-intersection patches.5 \; K# r, u- g* G' Z% p2 C
  my-column       ;; the column of the intersection counting from the upper left corner of the
9 Y- h! H! }5 E) d9 @6 q: _! I5 s                  ;; world.  -1 for non-intersection patches.
  B0 P  o( h7 }8 u6 L: Y7 d( ~- I  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 W" e# |. P% N$ u
  auto?           ;; whether or not this intersection will switch automatically.
/ R) N3 ~" w4 B* Y                  ;; false for non-intersection patches.
+ U' B, p6 I7 S4 @1 o]! ~2 }' I9 D1 O% q: j5 }& d

  e, z( u6 g6 r" y& n: o4 x
& Q$ m& L/ J4 x: _& m  v7 R;;;;;;;;;;;;;;;;;;;;;;
$ z/ O* [, H" j; M: g1 C* d;; Setup Procedures ;;% R6 M$ f& b, p; K$ X, J1 o) w5 R
;;;;;;;;;;;;;;;;;;;;;;! f) v+ h1 F; B7 G% M
; Q; @3 }+ N3 `0 z
;; Initialize the display by giving the global and patch variables initial values.. n6 M# m7 k+ [* g0 Y. @7 O
;; Create num-cars of turtles if there are enough road patches for one turtle to
/ }4 P7 Y: K. R4 P;; be created per road patch. Set up the plots.
3 a) }+ o# m" c2 `7 uto setup: K; T! Z# j( K, E' n9 Z3 |
  ca4 L7 k; h, O, k; Z# ]0 k/ z2 _
  setup-globals
: q( _$ U) ^. I8 u/ e
# {3 v- y% F1 n0 l9 {  ;; First we ask the patches to draw themselves and set up a few variables3 N+ [, J% }# s4 S1 Q9 \1 a5 H
  setup-patches3 G1 _# C8 r! \# k* K5 X! k$ C, k  N( L
  make-current one-of intersections
1 Q  q! w/ K+ |! k! v! v  label-current
) N) o# K- ]* V  I7 U% N$ d' S. L$ [6 X! A# d
  set-default-shape turtles "car"& e, C! T$ h( p$ ^4 n

: E: t, F8 b( r% H6 _5 Q6 [" O  if (num-cars > count roads)
7 l4 h) [$ |" O7 ^1 ^" W2 w  [
! u: K# ]- P- p& N2 _    user-message (word "There are too many cars for the amount of "# M0 S9 d0 _, P9 g
                       "road.  Either increase the amount of roads "/ j1 k4 v- P3 ]7 D+ {( _6 ~
                       "by increasing the GRID-SIZE-X or "9 r4 g% K3 N/ |3 {) N- l: Z/ `
                       "GRID-SIZE-Y sliders, or decrease the ". v0 ^' Z* U5 g% R2 W
                       "number of cars by lowering the NUMBER slider.\n"
8 U  M3 M2 m9 I9 S1 G5 a                       "The setup has stopped.")3 R6 b7 I& u$ C$ S" G( K
    stop
% }# Z$ [, k- C9 H! e, c1 j  ]( V1 j" x' J0 O- L8 @" m+ Z( q
+ U; Z3 {; E( l/ }! [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
2 }6 b3 W5 C' x: W& C& s  crt num-cars1 A' J4 e  G) ?. ^% y% C
  [
/ \/ S  |8 s( K! ]    setup-cars
( W; g' O8 |) [    set-car-color4 c9 i- a1 @$ ]( R! B
    record-data
% o: j7 j/ b/ h0 E9 f  ]
7 ]+ t5 r' m. E: X" z$ v( Z& Q; W  ?; Y" [( H2 U
  ;; give the turtles an initial speed
5 M2 w/ {* l/ W0 J; Z' O  ask turtles [ set-car-speed ], K4 Y3 z) n' r4 ~+ N$ J. I

9 }; \( a3 L6 E* f- N4 _) b& d  reset-ticks
9 h) ~4 o. k- y' R9 b# x5 p! m- lend: x5 C) z+ O2 X5 p. r

' w9 T% S" i$ W4 h: D6 m, F+ i;; Initialize the global variables to appropriate values
( v3 L1 Z- p! k: h: @/ ~9 Wto setup-globals
& n  G) n, q  j  set current-light nobody ;; just for now, since there are no lights yet) m: p7 d$ h9 S
  set phase 03 B7 u, F" t* s- j
  set num-cars-stopped 0: W* a  f) }8 ~3 g3 _( U( ^# q; A5 T
  set grid-x-inc world-width / grid-size-x
) q) _% |8 b7 V( z0 ]  set grid-y-inc world-height / grid-size-y
& q! w( L+ O3 @& r0 m; D* V
( i: G/ H" g  H/ ?1 p! z  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. d6 e3 J; R) \7 @( _4 m
  set acceleration 0.099
( h+ G6 C, d* W* Eend
" b3 q6 e3 q4 J; E# z# h
" T8 `0 D; a2 c: A4 N9 d; H;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 U) {! F) M+ P! ^
;; and initialize the traffic lights to one setting9 x, J$ f, V; ^2 s$ @6 \
to setup-patches9 j. Q1 ?- \' Z( a5 i+ X
  ;; initialize the patch-owned variables and color the patches to a base-color: C( x! b- f  H
  ask patches& v0 s6 Y6 S& R
  [
& p( g' D  h) e' B2 u4 V: Y    set intersection? false
4 e* T% ^) [9 n    set auto? false
$ y' U% g0 ]" s( T" S, M2 k    set green-light-up? true; d' l1 d% z: D" [7 k5 T
    set my-row -1: U- F7 G2 F2 ^
    set my-column -1
% ?& M  d7 _: r" y: k    set my-phase -1
+ ^$ ]6 p, @9 q+ y6 X    set pcolor brown + 3
3 E& m/ E  ]: A2 i$ x  D( l  ]8 M, ~' x, k+ \6 ~, J
4 x) P. e0 M5 b' s! }. ^. I
  ;; initialize the global variables that hold patch agentsets
4 ?) S  `9 z$ e$ l& {0 N, i: U& u  set roads patches with
) X7 q3 l* T( J0 ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  h- J7 @& U9 w, Z' I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: L& G9 a, t2 q8 _& |1 U  set intersections roads with
& i4 Q/ Q2 {( d; M3 t* H0 F) Q- V    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
2 m4 A, R$ n3 @% m# o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 \+ O( R4 k5 y2 {& P6 U
8 N0 ^! o0 W; b+ `  c7 ~  ask roads [ set pcolor white ]
4 J' `0 }! }/ n    setup-intersections  V- L# R) f5 R0 Z2 a" _0 A
end
! [) `7 i8 o5 n+ ]: R$ B1 j其中定义道路的句子,如下所示,是什么意思啊?
$ G; g9 _2 f1 Y- m2 h! ^! @ set roads patches with
! Y0 D- Z  L" D. R( i    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ c2 i9 p) f, O: M- J1 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 C- N& [5 w  y' @  h8 `0 |1 f( g6 A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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