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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。# l) ]+ N! S- V+ m' x
netlogo自带的social science--traffic grid这一例子当中,
# j$ G+ _2 Y: s2 r" j! s8 ^5 \globals
+ L% A' e0 [% n+ t[1 Y! [7 |3 b& D! m2 |
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
$ d1 ?3 f5 f- X  U& a* q3 A7 m( ~  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, C. {5 _+ z& D5 j0 H4 R$ z* U3 Y" P  acceleration             ;; the constant that controls how much a car speeds up or slows down by if1 a. F% D: u6 r. {' m( z1 t
                           ;; it is to accelerate or decelerate5 H: O2 k0 P% Z' j* g. b% z
  phase                    ;; keeps track of the phase, D9 Q# r) ^: q: L9 E
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" C+ Z: B) O0 W! W$ Z  `  current-light            ;; the currently selected light5 N  M7 P7 Q) l
  k8 {) H8 n  O% ?1 `' u. o& c2 F
  ;; patch agentsets# h9 [$ G. o4 ~; D2 B
  intersections ;; agentset containing the patches that are intersections* K4 p& u4 s1 p0 c) `
  roads         ;; agentset containing the patches that are roads& o+ z( r$ {7 ]
]8 ?+ Y+ ?. a7 K, R: `2 I7 [! y
+ `8 N8 r6 P7 M! J! G- V+ v
turtles-own3 t  V9 [" ?$ j
[
1 f; w" S) N( }3 A- l3 q  speed     ;; the speed of the turtle" O- r( x0 A; h$ ^3 _7 R' K+ @
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
) z4 ~9 E, D* e( h) R  wait-time ;; the amount of time since the last time a turtle has moved
+ q8 u3 f) K9 D4 ?9 W9 m; ?8 \" }]
* s1 W' n$ b) U- p3 {5 Z. W0 j. s( _; a9 a7 |) o7 l
patches-own
: ^5 q8 S4 A' N: |/ V9 j, U* ][
3 Q1 ]' S! p6 i( B' f  intersection?   ;; true if the patch is at the intersection of two roads. M* Y- U8 V+ }- T$ h" M0 k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" ]+ P7 z* @# i                  ;; false for a non-intersection patches.( }( s6 d0 a# X9 ~: W! S, V2 e2 I
  my-row          ;; the row of the intersection counting from the upper left corner of the
) H) Q) g6 b7 t' J                  ;; world.  -1 for non-intersection patches.
, ?+ _* g: b5 j) g- u  my-column       ;; the column of the intersection counting from the upper left corner of the
( ^; I4 S5 e: c- x9 |4 q                  ;; world.  -1 for non-intersection patches.
4 }& [- E& G% q8 U" w! P- H, T5 T  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# l2 \1 k9 I- b+ \8 e* J+ \
  auto?           ;; whether or not this intersection will switch automatically.
# |1 K  [" D9 I3 C4 a0 {+ Z! u" `: V                  ;; false for non-intersection patches.! }' Y6 N7 G/ k0 O5 a2 \
]- c. c5 [# |& u" V+ @: c- b  y2 i
9 K5 m. Q6 v: b/ C. A
* O9 L+ l, j  S$ K6 O3 N, f# x. K+ t4 b
;;;;;;;;;;;;;;;;;;;;;;4 v6 E! {& i, L6 v) q, v
;; Setup Procedures ;;7 `: H7 N$ V3 F9 S1 z8 y4 {
;;;;;;;;;;;;;;;;;;;;;;
# `9 J0 O! j# C) E( k. k
9 A. b. J, _: J' y8 U;; Initialize the display by giving the global and patch variables initial values.' H+ \9 ^+ V% d3 J4 e
;; Create num-cars of turtles if there are enough road patches for one turtle to
& e; d$ l& c( p; m) z! W;; be created per road patch. Set up the plots.7 j4 l* a  H) ]: N
to setup! {/ _* K. P- |0 E& d  K0 W) F: J
  ca
6 K7 a$ k0 P$ `9 ~- g6 o: N9 {  setup-globals
7 g; Q0 V5 K6 O5 A( A/ _- f1 v& X, O% u. C+ z6 U3 Y1 l8 V
  ;; First we ask the patches to draw themselves and set up a few variables, R; _2 `4 }( a: y6 U  Q: Q
  setup-patches7 X' ?% q  A5 N' G* B6 r2 j
  make-current one-of intersections
% `' _, w7 I9 o% P1 J% Z9 v1 Y  label-current
& B0 h7 g" `1 f& @, K3 o, M# w
/ ^6 p( _- n( R& l1 |) U/ D# X  set-default-shape turtles "car", q" T6 r7 N9 n5 E3 D
2 z2 r- K6 w: `0 Q2 W% _
  if (num-cars > count roads)% ^% w$ W6 ?7 F3 X# S
  [
$ x+ x1 ?$ O/ a8 e" u$ w# m    user-message (word "There are too many cars for the amount of "
6 V1 C! F- I" ~' C                       "road.  Either increase the amount of roads "
! V5 I: l2 R! k) T  y; G% `                       "by increasing the GRID-SIZE-X or "2 t, S9 b# r7 F  H  _6 Q2 X2 w
                       "GRID-SIZE-Y sliders, or decrease the "
6 f" s0 @( N% ^& c                       "number of cars by lowering the NUMBER slider.\n"
% C0 G4 G" _0 T                       "The setup has stopped.")0 ^' G& P0 `; ~  t, _! i7 w- `
    stop2 p' _2 Z# u& w2 n- E
  ]$ w8 |" s0 e( G6 \, r
7 x# S2 p- d( \7 d
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
! O, O1 H! u+ \% R  crt num-cars2 c7 G- d" r$ B, Q" c* Y" s9 W6 Y7 S
  [9 [" J2 n- \" Q# Q4 ^# r$ ~
    setup-cars/ w8 u# R$ v' b& B  l: X' x
    set-car-color& G( o( B5 j2 B& P; [" P* C
    record-data8 ?  B6 Y/ E) x& G+ V+ ]
  ]3 Z& p# i& [' Z. ~# a4 n5 P
6 l7 Z) o# X- t& Y  O, Q
  ;; give the turtles an initial speed1 K8 w$ E7 |. p1 A$ E+ f
  ask turtles [ set-car-speed ]0 a3 Q& T+ R- `0 C+ D! i- y+ G& t0 K

( ]) r- x, G% m8 x: D0 D9 P5 L  reset-ticks
: I/ @8 N* k+ \" l) ~end
% U! G1 O$ G$ M
: c- S2 G( I6 z+ o( g4 a;; Initialize the global variables to appropriate values
1 V7 u1 \5 F6 {to setup-globals
  s; R2 _) Z5 Y& J0 Y* F1 t  set current-light nobody ;; just for now, since there are no lights yet
8 T: c9 ~  J" g  set phase 0
4 v$ W$ l- \+ ^! }: G( K  set num-cars-stopped 0! B4 n  r' D  p5 I# D, T
  set grid-x-inc world-width / grid-size-x, F9 c" ~. S) _) l
  set grid-y-inc world-height / grid-size-y
5 C4 a; O( `, x* T/ Z5 O6 N1 u: {7 S3 p6 C: \5 O* a& R
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ ~$ p. [; g/ N+ q. _  set acceleration 0.099
6 _- E; p  i, [5 t6 p, Y! }- u$ Send9 e# u! c  t% p" D+ Z/ T( o

6 ^$ D6 N; D/ B1 Z5 G3 N;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
8 a8 `- r; k4 p+ x;; and initialize the traffic lights to one setting
3 |' [. F8 O/ t$ Y" i- Tto setup-patches
, L7 K) W6 h& m% t, d: {. q  ;; initialize the patch-owned variables and color the patches to a base-color4 D# `4 N: Z% o4 h/ z) F" Q; ?+ }
  ask patches7 p# f; k* ^- b
  [6 [5 {9 I! \5 V. A5 \9 G. U
    set intersection? false
) f+ l/ D/ p. ?+ h    set auto? false* t6 O" ~" ~: W  e  v
    set green-light-up? true
3 j8 g7 j, L& G2 ~( \$ R' ^    set my-row -1
- u& k1 H) f/ q    set my-column -1
- W" t& b% n( N+ V    set my-phase -1
) W' M' }# R" t& }2 A3 m    set pcolor brown + 3
& y! U* v) n* [. u/ g" d. [. E  ]
" H" m( U# P) c# D  F- U9 d
; Y) K' ~$ `" N7 b  ;; initialize the global variables that hold patch agentsets
, ^6 `. z) x$ W: e' L) b7 P1 U9 G  set roads patches with
& j( J- _- P  I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  ^% q3 f4 E! i9 b5 L  e
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], o/ v( E, `; _1 i
  set intersections roads with% I0 j- }, A% d& L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 y+ q3 P8 }- _& d3 E: Z) ]* f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; H# O: b( o3 T% o7 o. U' l! ?8 M" ]" J6 L; W7 U
  ask roads [ set pcolor white ]
! Q% s8 t. u2 h    setup-intersections% M+ I* U5 q8 H1 B4 P. Y; Q
end  f3 R* M4 _* T& p8 Z3 h
其中定义道路的句子,如下所示,是什么意思啊?
$ r% I! ]+ L8 X$ b set roads patches with
8 Q5 d' `7 b6 P- @* A' L7 y! o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& O1 D2 O$ ~7 |    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, F  O/ q. F; [) _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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