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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。7 ?* v1 h6 `' \# h8 B
netlogo自带的social science--traffic grid这一例子当中,
6 |8 b$ W7 ~1 Yglobals# U: b; Q: ?% r3 z' y& d% n
[; g+ T, B2 ?$ Q/ X+ O) `
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) Q4 u; b- g* p  u6 C5 K+ a# e  grid-y-inc               ;; the amount of patches in between two roads in the y direction
& z$ w3 x0 T8 h9 N1 B  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  X. `: H7 a) e. Y: G- s/ \" F                           ;; it is to accelerate or decelerate6 q. h- n2 D9 M2 i/ w1 ~
  phase                    ;; keeps track of the phase1 t7 L8 ^5 X+ S4 a4 g
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" ], ^: ^# H8 V% L5 m1 p  R  current-light            ;; the currently selected light, G7 H4 Q" R0 \; h' l

* A% D1 e+ c; S  ;; patch agentsets2 `, l! I: X& d" s2 G& S+ B. D* B* Y: _: t
  intersections ;; agentset containing the patches that are intersections
  }, i  T3 E5 d# e) X# s7 ~- R  roads         ;; agentset containing the patches that are roads
0 U' l, |& Q- n& f]& q4 K  }; o1 ]( n# }1 m
* I2 z$ `. D% q4 a: _6 `! B  i
turtles-own
, B6 Q$ Y" F1 X4 r! U[
  q% w2 V: U0 e/ z- z7 o. R0 U5 M% _  speed     ;; the speed of the turtle
9 W$ V8 e) P% r7 i6 e" P  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# C( d  V9 F! Q6 v. y  wait-time ;; the amount of time since the last time a turtle has moved
, H( F2 a4 M5 O& J( |3 z; `/ e]+ X) Q4 z" h4 Y

) i' A" C- r. B" X6 Xpatches-own/ K& S2 [8 R& h1 v4 \
[9 @; `' p7 v# D% K4 w' p
  intersection?   ;; true if the patch is at the intersection of two roads
' T1 V( R( y0 I( h% \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
; s( B- `5 X, e, M! J; ]                  ;; false for a non-intersection patches.
& W5 n& `3 e" e  my-row          ;; the row of the intersection counting from the upper left corner of the
8 _; C4 l, S3 {5 _6 t0 p; n                  ;; world.  -1 for non-intersection patches.* r1 C# C  ~  u( ], s# t
  my-column       ;; the column of the intersection counting from the upper left corner of the- O. L3 H6 t' F  K# e& d' k. W8 l
                  ;; world.  -1 for non-intersection patches.
: h4 e8 k% o) V' K' e* p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.8 C6 j% u0 \0 V* B
  auto?           ;; whether or not this intersection will switch automatically.7 m% g" {; ~, n/ f, ~& h& ]( c
                  ;; false for non-intersection patches.
; U: `1 X) H- I2 u6 i]& X% ]$ m% V% y# X% M' ^

7 W5 R$ f& e5 b0 G3 x: {
* w# s& }' q7 R8 q# u4 Z* `+ M;;;;;;;;;;;;;;;;;;;;;;; m4 ?  F2 o4 q4 W. k
;; Setup Procedures ;;6 Q9 w5 |8 S. [; f+ D* o
;;;;;;;;;;;;;;;;;;;;;;
4 C% P; l+ m- t' M- l8 S6 s' W' b, z9 r
;; Initialize the display by giving the global and patch variables initial values.) z: P* W: p# N1 n$ N. q5 }
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 L, G' G$ e1 r$ l+ V;; be created per road patch. Set up the plots.
) m0 O) ?2 T) w; B% bto setup
& V2 V" }- S+ M' j  ca
. b9 o# Q( u; o) Z5 F& [  setup-globals7 ?' z9 E+ o* e9 K: Z) D, J

5 a+ ]+ f0 v) W( K+ a  ;; First we ask the patches to draw themselves and set up a few variables; p+ j5 u% H4 n! t
  setup-patches
  X3 |( T" ~! q, g  make-current one-of intersections
: ^* ~2 h9 W6 ]7 w- D8 i  label-current
3 |5 [! x2 x0 `+ F4 |
$ E$ \7 q$ Z0 Y1 L8 b  set-default-shape turtles "car"3 G1 r6 T( y" c! N. }

2 b4 r$ i3 q" S. }% i& h( x  if (num-cars > count roads)- [: W, k0 _( Y6 e& N$ {
  [' Q+ i4 b4 {8 M: H) ]* V4 n& o
    user-message (word "There are too many cars for the amount of "2 D( e; ^( ~5 N0 w2 x
                       "road.  Either increase the amount of roads "
& [3 S  f8 G2 Z' p1 j1 [; p" k                       "by increasing the GRID-SIZE-X or "
# ]2 I- H: ]. |                       "GRID-SIZE-Y sliders, or decrease the "1 V7 v  Q2 k7 A; s" @8 \' [
                       "number of cars by lowering the NUMBER slider.\n"
, C% t: P( t1 [% |2 |$ D3 V                       "The setup has stopped.")
0 y% K+ h& S% V$ v$ g; {    stop. m: o4 S  |$ s5 [2 I
  ], y) ?- E+ i! N' m+ @% Z- ?/ [
9 m9 K3 w2 M: e% n) l0 L
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- K. Y6 _, p  j$ ^  crt num-cars
4 X7 R6 \5 }9 z1 Z  [* z2 K- R) Q% u
    setup-cars
) A2 U3 }+ {; o/ _- e( E    set-car-color
# z/ J4 Q( X, V* h& _! M    record-data' }! o: M8 z9 W5 b/ d" |, Q/ }
  ]
1 z* G: g8 R- f3 a6 u
/ s$ m. {& q, w  ;; give the turtles an initial speed! {7 c7 G& o1 q3 a0 L& X3 V
  ask turtles [ set-car-speed ]
5 F1 v& m6 z  o" {5 V( B+ p! V) b/ `
  reset-ticks! {' q$ N- V$ W, L+ D
end
+ r2 k3 ?5 m; V$ `7 Y, R0 ?( W7 R/ r' p* b( ]* i
;; Initialize the global variables to appropriate values. y) q" I. ~& j: a) E7 K9 K0 i
to setup-globals/ E) W/ e; F% H; w5 f" L
  set current-light nobody ;; just for now, since there are no lights yet9 O6 A+ E4 i5 y; e
  set phase 04 t; l3 ?- \/ _
  set num-cars-stopped 09 O/ R7 b. d. [. c. j' Q
  set grid-x-inc world-width / grid-size-x, x/ X$ V! @7 I; I
  set grid-y-inc world-height / grid-size-y
- @' Q$ }$ `0 U& J2 ]5 `3 Y8 L& S
2 `- [7 _" A/ s5 x  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary3 y" u5 t2 S+ j* D) {7 v
  set acceleration 0.099
' c- [* g' s6 N3 a3 M; Mend  `1 \% J' w! u$ H- x* O8 E1 |

9 S6 p- e) g7 G3 {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,  g6 Q7 A% C( \% W) r
;; and initialize the traffic lights to one setting
2 \; I) X& [. ]5 }to setup-patches+ Z) I, f$ x5 z+ R6 n
  ;; initialize the patch-owned variables and color the patches to a base-color3 l2 O3 @5 p8 V2 d- R* |
  ask patches
- M- L% L9 F% B" S  [
6 z- @) X* X6 C2 P9 k: B    set intersection? false5 i+ H* q; I  J9 j( H9 }% N5 S3 d
    set auto? false% j. @2 E  m2 K# T7 a3 I6 S
    set green-light-up? true4 _5 j* i7 C3 ^0 `
    set my-row -11 B0 a5 a/ D# x% {' i- G
    set my-column -1+ `, L( f9 ?, b, Z
    set my-phase -1
" |: u% ^9 b$ f3 ?6 ^6 S    set pcolor brown + 3/ y# s4 L) _- _/ D, k
  ]
' ?9 d1 l  c1 a! [! y9 n
- [1 G9 u5 p5 o7 d' O3 L, K  ;; initialize the global variables that hold patch agentsets& W/ s1 ]+ W2 J2 V8 v2 `
  set roads patches with- Z. G) d( G9 Y8 `% h- [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 o* Q: Q+ L) W: ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( @0 N( }, y+ }* L2 \1 N  set intersections roads with, k" r9 Q4 c; H+ t( h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
# H2 d* E. z6 F0 L9 N' |3 p5 l5 U    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' _' T. |4 D/ a5 W
% h1 `. R; m# \. s/ S. l" ^  ask roads [ set pcolor white ]$ w, }& c, @0 r" D
    setup-intersections
1 f1 N  B8 ]) t  u" U$ p8 eend- h% ]& O# x2 l& {5 h
其中定义道路的句子,如下所示,是什么意思啊?5 ~3 q, `% l$ _& a; X" `. K& Q
set roads patches with1 P7 v0 w/ j2 d- ]1 ~- C2 [
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; _) Y& t- p0 l' y; v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. _2 p& [- f5 g' R: D& ~. U; Z5 S
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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