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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。# w( E; T+ {4 D- Y+ G& x! A& I
netlogo自带的social science--traffic grid这一例子当中,) V1 g8 `6 m8 R0 f3 y
globals
% h* H3 ]) a* |. i: W% B& w; [9 i[
% ]& y. k9 B# {5 z1 q, J8 k% J+ T  grid-x-inc               ;; the amount of patches in between two roads in the x direction  l7 {$ k& G9 D4 m
  grid-y-inc               ;; the amount of patches in between two roads in the y direction* x7 E# y) s7 t% w
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
$ w. Q- h+ s+ q                           ;; it is to accelerate or decelerate
8 \4 w4 O/ P8 W  phase                    ;; keeps track of the phase
1 s' h' D6 H$ L2 i, t2 S3 u# W- k& G  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' ~0 e. |# |  {4 M3 n7 t
  current-light            ;; the currently selected light
, x1 \- i* D" @% s) J
) Y3 i9 h& Y+ e/ l, f( u  ;; patch agentsets# o1 ?2 |5 l0 o0 v0 d6 @  C3 F
  intersections ;; agentset containing the patches that are intersections. V+ `0 l5 m& G3 N: G: a2 \
  roads         ;; agentset containing the patches that are roads
8 `' N5 h) n& ^; M]4 V' I0 [: N  w8 T* i  P
, l3 ^# C9 m" ?' t4 P: Q6 a: S2 I
turtles-own7 B1 O' @3 T" E$ X8 R
[. D: s  m* W; i! B. v
  speed     ;; the speed of the turtle
4 ^$ K  X' G9 D8 ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ P$ n% ?+ E2 h8 h  wait-time ;; the amount of time since the last time a turtle has moved
$ Y; g  V3 t( o  A8 |8 \* k]0 c+ d3 r* F3 J. V

0 Q, _+ L, |3 U3 H% Fpatches-own; @0 U- R2 T/ R" o/ F
[) G0 W! |. o' d4 A5 p5 Q
  intersection?   ;; true if the patch is at the intersection of two roads7 u0 j' ?  K* j7 I5 b
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 ~7 E: h9 _& s/ U
                  ;; false for a non-intersection patches.1 X; _) H. ^$ c; g; F1 o3 P8 k
  my-row          ;; the row of the intersection counting from the upper left corner of the) ]* t* o/ c" }9 J' m
                  ;; world.  -1 for non-intersection patches.
2 \$ b6 X* `8 l  m: Y  my-column       ;; the column of the intersection counting from the upper left corner of the
+ q5 [, I! P0 f* B6 ]% }                  ;; world.  -1 for non-intersection patches.
9 }6 q4 T1 d' J4 I8 `1 i  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( W: L6 K4 j8 S: d2 C$ W
  auto?           ;; whether or not this intersection will switch automatically.9 k! X6 V! S* @- j( f& U+ G% b
                  ;; false for non-intersection patches.
+ G# {3 ^' q: O  v]
7 X  d/ t  l% q8 M* `: L: o8 r, E2 E
6 }7 Y: r  Q4 u6 h- q% B% }% i; J! c$ s# @6 V, @9 X  {) s
;;;;;;;;;;;;;;;;;;;;;;
) D' |3 t+ Y' T/ {, {1 o& U5 C* d;; Setup Procedures ;;
5 F  J4 J% k2 G4 U5 [* N/ A: w;;;;;;;;;;;;;;;;;;;;;;
" v4 n; n8 B2 a8 U) D! y, @
0 Q9 K3 C8 i+ n  {; Y;; Initialize the display by giving the global and patch variables initial values.  H3 H2 a1 l# i. j* L, u
;; Create num-cars of turtles if there are enough road patches for one turtle to' G/ J5 ^- Y  w* ~) @% e
;; be created per road patch. Set up the plots.
  z. c) _  G$ bto setup
6 @% {9 Q+ T& d1 C. e  ca$ `8 f1 }; R1 T2 J0 g# X+ ]
  setup-globals% N) ~6 x; |  b5 q% c) c4 P

' ?9 }, E8 L; M4 T* G0 Y+ F  ;; First we ask the patches to draw themselves and set up a few variables
: \, }$ Y  l, n9 m. h( \- `  setup-patches, [( c7 A' ]: z" j! R/ z1 W2 P
  make-current one-of intersections
0 \0 W9 M, z9 ~4 c  {  label-current0 O* J9 b7 g3 g' E
2 K$ }1 _" N! t6 k" a& M
  set-default-shape turtles "car"
. Z  \/ B( m  C0 r0 i$ `: j9 |8 v: P! P, \. b, A6 g5 r& _
  if (num-cars > count roads)9 u  p) R; W$ B8 V) p
  [2 H1 _& f( \( F& y4 q( w7 e
    user-message (word "There are too many cars for the amount of "1 e6 z) p& [9 R% }7 k
                       "road.  Either increase the amount of roads "5 P0 R6 r8 `& T& g4 K
                       "by increasing the GRID-SIZE-X or "
' o. p0 U0 x1 \. k( J4 T                       "GRID-SIZE-Y sliders, or decrease the "
; }( z7 H. U) o                       "number of cars by lowering the NUMBER slider.\n"7 p4 N: w7 R- ?
                       "The setup has stopped.")' A, d2 \* Q# J( k4 A
    stop
- Y/ B6 [) |& `2 n$ \1 C0 R" [  ]3 F! q0 I; R0 ^$ D, ~' W  |
! ^- Z) q- A: Y- Q5 p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& R0 O; ^0 s0 a; K' O0 }" a8 W
  crt num-cars% l; e: z- n; ]. m
  [
0 E2 K9 ~" y6 k+ `# ?( Q    setup-cars
" V6 C- p! }, ?+ \6 l9 D    set-car-color
  ^) N5 O$ F0 r4 O9 E# a    record-data) Z4 ^/ s* [4 |6 X! a! i9 o
  ]" M: p; S5 y4 S% ^- Y5 T

& ?3 @/ e# S- V. D3 C; S1 F  ;; give the turtles an initial speed& c$ c" j; P2 V1 b  i$ m! x7 L1 S1 r
  ask turtles [ set-car-speed ]5 `/ G6 b$ |; x% ?  E$ J
0 P6 k. [' G9 f' L
  reset-ticks2 J) O0 H2 k" ?( L" |
end% H# T8 z5 [2 D. e4 u; {2 G

! P" V- ^; s! T& _% u;; Initialize the global variables to appropriate values
% K+ q8 T* y8 e$ I8 G5 E: O5 m# Fto setup-globals' R4 o* c5 z1 G0 t! F0 p& X& j1 v8 ?
  set current-light nobody ;; just for now, since there are no lights yet
5 D7 s! J/ F6 L& V8 U4 i  set phase 0
1 |) b! B' |$ [1 W; W, `% Q  set num-cars-stopped 0& _9 f: h: N  M4 @
  set grid-x-inc world-width / grid-size-x1 p0 e5 v5 G9 a# l6 Y
  set grid-y-inc world-height / grid-size-y6 ]9 ]9 g% F9 G* _4 ?* X3 R! m

, F2 e( a) X0 D: K4 R( S  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- u+ B( C/ [& w4 N+ T1 A
  set acceleration 0.0997 Y# L3 o2 P6 ^% ?! l* X. R
end3 j/ y- u% E# r

% Y$ `- e* d# D: m; V;; Make the patches have appropriate colors, set up the roads and intersections agentsets,8 T+ `: Z" T) Z) K5 H
;; and initialize the traffic lights to one setting8 j8 {4 h2 Y' U8 M
to setup-patches
: I1 t* O6 u, X  ;; initialize the patch-owned variables and color the patches to a base-color5 N, z5 e+ `( u# a
  ask patches
- u( W) E- B/ {1 \7 X) r* G  [
& @/ e; _# ?( i8 p    set intersection? false
: w' k4 Y, y# r/ L    set auto? false! c( H  r( B3 w; _
    set green-light-up? true- v1 d, Z/ Y" Q2 O' \
    set my-row -1
! X: }7 ^* |- D" [- h4 @    set my-column -17 |' `4 y) Q0 f, s' j
    set my-phase -1
7 f9 s) i2 h0 u    set pcolor brown + 3
% z" k2 q/ U; h' u8 g1 m1 f* {' p  ]" H6 G% z. A) z6 V2 b
6 \$ s) t+ S: g
  ;; initialize the global variables that hold patch agentsets
6 x) \- X7 U2 J' }% z; p8 g  set roads patches with2 T/ o* F5 {1 E
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, S: W  t. d  A( U4 n8 X$ G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 a+ n- g: r. ~& H" k8 B  set intersections roads with
1 E1 A! E- L5 t, `. @8 h4 q  z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and3 M& y; |1 j1 t. {* \* O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  `) O/ c2 v* G! m, T: z5 D
) g/ M$ T) Y) r  x7 t  ask roads [ set pcolor white ]- Y8 i! U5 N$ u
    setup-intersections- y+ G! q) S( l6 ]) |# n1 s
end
! j+ V  ?. d% ?9 ^4 Y8 a7 E/ @其中定义道路的句子,如下所示,是什么意思啊?; z/ j5 H) g/ _/ m& ]1 U. R
set roads patches with- A; L. c8 i4 \2 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! `4 Q0 D1 v$ l3 X& i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. @7 |7 Y- a+ a, m# d
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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