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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。' F- m# V1 I4 d7 G- J# ?& I( F
netlogo自带的social science--traffic grid这一例子当中,
9 b5 [4 ~3 G; y) E6 h1 hglobals# `8 k* W( t0 u3 ~
[% I9 \9 }3 i, n3 J4 c  a
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
" F+ t/ g" I4 r; |: [! U9 M  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* d; c6 P, k) m4 o0 p7 y  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( u/ ]. @( p4 `6 h3 t) z                           ;; it is to accelerate or decelerate
% [# H- a$ g: D" u) ]8 e& [0 g  phase                    ;; keeps track of the phase
. f& X4 w; I: y' i  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. R% }/ M) h1 f2 S! C. J! C, e* a$ t  current-light            ;; the currently selected light
: ]" D+ ~/ e& F- N1 K
" W* h/ p0 X7 X+ @  Z% t* o8 J  ;; patch agentsets
) @; o7 x) _0 ]/ d8 m  intersections ;; agentset containing the patches that are intersections% p# Y( p( n) U- V! S
  roads         ;; agentset containing the patches that are roads
9 t4 g) `* z' c& A/ O]
/ Y2 D& K/ H1 ?3 J8 {+ {
/ Y- d9 y* i6 Fturtles-own
1 E. L: a) `0 J* Y2 X5 d[+ F  |$ R% x- C$ ~6 |! j3 v/ Z& U" G9 b
  speed     ;; the speed of the turtle
) x1 F5 {3 R; B3 t7 Q* T/ ~% }* L" a% o  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 g" i9 }! u0 ~+ N7 U  wait-time ;; the amount of time since the last time a turtle has moved, ?) f- E: [5 ?2 z
]: N+ ^( I6 T' [  n' ~0 _% _7 t" p
6 s- `- ]" k1 [4 s" X7 o5 r2 Z
patches-own
* ^! H% J3 z' i% O- Y  O# n! e% y[: T; d9 N' z2 J+ h& O- x
  intersection?   ;; true if the patch is at the intersection of two roads( D2 D+ x( Q8 {! B& D+ H7 ^
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 N! X' F) |: U                  ;; false for a non-intersection patches.5 Y& V4 g# B# M* f3 ]& T9 _9 \& a
  my-row          ;; the row of the intersection counting from the upper left corner of the1 x/ ^$ n) B; U4 B" F8 `
                  ;; world.  -1 for non-intersection patches.) S4 n& F0 q) N* W: {$ c
  my-column       ;; the column of the intersection counting from the upper left corner of the
* n- u- Y' H; z                  ;; world.  -1 for non-intersection patches.+ _; s! Y- Y2 J. p7 E+ C% |
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.5 F; P* {! s( ~4 L  j$ f
  auto?           ;; whether or not this intersection will switch automatically.
3 k* q$ X" `, \% [1 X                  ;; false for non-intersection patches.  V3 U5 U/ @/ w5 U  F
]
) \: x; G/ ?$ I! U6 m/ e9 N4 w3 N; Q! z0 H7 \9 X7 ^  v! X% N! l- T' A2 H
2 x, e) d6 j8 i& c9 ]3 {/ P! A
;;;;;;;;;;;;;;;;;;;;;;
3 X3 u; q- _6 @& g3 F1 Q0 B3 R;; Setup Procedures ;;
7 H5 u) n( E# H/ r; Z. T;;;;;;;;;;;;;;;;;;;;;;0 u" R9 j6 k: m# w8 j/ Q

+ a- X- f+ y" r$ F# g;; Initialize the display by giving the global and patch variables initial values.
9 z  I( l3 a$ \* J, [% M; |+ q;; Create num-cars of turtles if there are enough road patches for one turtle to# l+ r; A+ ~/ g7 }5 p( u
;; be created per road patch. Set up the plots.# x3 G' X3 J/ e
to setup( X8 \. j7 J+ G& e# U& f
  ca/ k; q4 H& l& R) P
  setup-globals( D3 ]( b& ?) j' Q  h* R4 x! ^

2 J. V' N/ w+ D% a" {2 L  ;; First we ask the patches to draw themselves and set up a few variables, |4 h5 }7 O1 G
  setup-patches
8 E- |0 N2 T. C$ H, k: n4 o8 H' Y4 I& z  make-current one-of intersections
0 F5 U1 f4 o2 A" {% S4 J  label-current" l: i) b5 O# x+ e+ K+ ?+ d
9 c* k+ s- |( N9 T/ J8 U/ e* d
  set-default-shape turtles "car"9 A7 S+ `, k) V# r

2 @# ]5 W  p; i9 p  if (num-cars > count roads)6 o% F9 J7 p/ g5 l0 }" m; P7 M- J- V
  [  J- P$ T; f# j7 \* x1 a6 |! P0 }
    user-message (word "There are too many cars for the amount of "
' {* U9 `* c) ?0 ^" a8 c                       "road.  Either increase the amount of roads "
" r; j5 K1 @0 `/ P$ Q                       "by increasing the GRID-SIZE-X or "
+ t  p! f! E" Q  O; Z                       "GRID-SIZE-Y sliders, or decrease the "- g6 g% j7 b; L; X- |& T+ g2 b) J
                       "number of cars by lowering the NUMBER slider.\n"6 w4 Q+ }3 k6 i$ I8 w
                       "The setup has stopped.")7 G4 I& N" M! c8 [8 t) Y0 p; _# h, C
    stop& ]: U2 f8 y' }/ B* h6 `# P
  ]
6 O: T/ q! F' ]$ h2 S  ]  }
/ ?- l) V& S8 }# K, [  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ R! ?# ^( E( b! e: ^  crt num-cars
7 ]+ }; j* j* S6 ^  [. h4 Q4 {( n  s# R( i. k
    setup-cars' o4 C* g0 [: ?3 D/ y0 j
    set-car-color! D6 x; O2 Z7 d+ Z/ P: J! p
    record-data: k, e  H' I" W
  ]8 v7 G$ f+ d/ M
7 y5 `. k9 h3 E3 ^0 ~
  ;; give the turtles an initial speed6 c+ S; }4 ]( i; |/ S$ Q6 Z
  ask turtles [ set-car-speed ]  L' M! I7 K, _1 ?+ m

/ l! q! d& Y. Z8 |4 m  e  reset-ticks+ }! h% K, G' W! W( J, M
end1 @# u3 N0 C- N* h
9 v0 Y! {1 v( v$ q& a- T
;; Initialize the global variables to appropriate values$ V5 x- k5 ]: b8 z, v
to setup-globals
% i- [4 G: ?4 |8 D- W% Z% C  set current-light nobody ;; just for now, since there are no lights yet
/ b1 H/ J7 q/ |/ g: P$ g& H  set phase 0
; g# s. o) O/ P4 M  set num-cars-stopped 0
( G4 _) u$ c9 u0 p) ^  set grid-x-inc world-width / grid-size-x
; V  e) n" j1 V3 w/ ^2 p! {* z  set grid-y-inc world-height / grid-size-y- P( B: e$ ~# D" |

) n3 F/ T* N. E( l$ q$ ]6 y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, h2 x$ m/ M( S1 N6 ~2 u) L2 o
  set acceleration 0.099  R! V; }( l, s  y" [
end5 k) s+ z1 p5 J8 H/ a6 }
) |9 q  @" t, c& f* {
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% }) Z4 T0 ?- u  J3 q  ]7 \; e;; and initialize the traffic lights to one setting5 v0 T6 W" A+ @8 U
to setup-patches
/ b) x6 V; R$ ^3 k8 ^* D# p  ;; initialize the patch-owned variables and color the patches to a base-color
9 O5 {  e( H' {1 N) P& w! @  ask patches
+ q$ l2 `% P2 Q9 O- g2 I& ^  [
/ l4 U9 p; ~9 S' Z0 U" v    set intersection? false8 ~3 M3 j  u. ?1 a! _% V
    set auto? false. ?) Z6 R5 s4 X# |
    set green-light-up? true% R# o, x) i2 \* m) l- k1 p, f
    set my-row -15 N0 u. Y: i5 {) F; W
    set my-column -1" f4 z, b! D6 W1 @
    set my-phase -1: m) i7 l/ k5 y6 Z& \- x
    set pcolor brown + 3
/ C: c; p% @4 `9 e- B  ]
: S  P6 @6 X3 c& E
$ c1 Q) c. n5 v7 b' @% {  T  ;; initialize the global variables that hold patch agentsets
5 X$ t# z8 r$ b) v# [) `! o  set roads patches with; f  n3 s- N/ V9 i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 ~% J$ D0 U& ^2 X' I$ J$ G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 N( Z: j3 N6 ^( {; t, I  set intersections roads with* }0 b+ l+ f8 \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and) m6 g. f0 H( ~( V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 R) s% }" F$ ~% J4 z
2 d2 y5 A8 z) I- o  ask roads [ set pcolor white ]
, a' ^% N: j4 X    setup-intersections2 `6 @* h& ~1 y4 s7 i
end" K! {; a& D3 C- ?6 [
其中定义道路的句子,如下所示,是什么意思啊?$ S- i9 r- d8 D) ~7 C9 g
set roads patches with
1 A2 z8 U0 u3 a  L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 P" F- ]0 r5 Q. ]3 W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, N/ d! J. j( X8 y" k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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