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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。
% C+ o/ t4 O# G  f: @netlogo自带的social science--traffic grid这一例子当中,
2 X. Z6 p' ]3 f3 ^/ {globals* p" ?4 O) v6 ?. O* k( t. b
[, y" h. Q7 ]6 Q0 F0 L
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 ]' C  [5 B+ f! D
  grid-y-inc               ;; the amount of patches in between two roads in the y direction' b( D, f% K8 n% b! W
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if% |# m, J5 d/ p1 n3 L; g8 y# e
                           ;; it is to accelerate or decelerate* `0 o: G& l. |! W- M, l$ T# f
  phase                    ;; keeps track of the phase4 s+ b. a1 Y! K9 p, n# M
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 M$ V- J2 t, o0 n  current-light            ;; the currently selected light
, A/ e2 M! G% W4 Z1 C. \' E* Z0 I/ @9 ^+ B- X) o2 h) p
  ;; patch agentsets
3 E" D: L% ^! e  intersections ;; agentset containing the patches that are intersections
* v3 b/ L, S; a0 U' h4 W  roads         ;; agentset containing the patches that are roads
4 u3 k9 _. S) o" T; B( X]
$ Q3 `$ G+ Z1 r  i1 P5 i: r8 _0 N" f- S
turtles-own7 S. d" [/ U; N2 n& ~# ~! l( `, O
[
; T/ f8 b4 b# |. `7 Y! B  speed     ;; the speed of the turtle4 Y& ]8 ~+ O( R: G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 c( z# d. Z+ x! S  C6 q  wait-time ;; the amount of time since the last time a turtle has moved* h5 N# h: C$ ]# l  Y* B& s8 j
]
9 U' v6 W$ h4 `4 R+ z& {, d
2 m6 j0 l3 l+ |, s) {/ F% K: Epatches-own' b& w7 A) L4 w5 S# t. ~9 e8 ^2 k  V
[
) P! K% \. e/ k2 x4 ]1 o  intersection?   ;; true if the patch is at the intersection of two roads
0 f% v' X4 L7 h) v  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# ]% e3 \0 v& n$ Y0 J4 x
                  ;; false for a non-intersection patches.4 D7 d; l2 F7 m$ r6 e
  my-row          ;; the row of the intersection counting from the upper left corner of the# i' r/ Y4 [- t8 x
                  ;; world.  -1 for non-intersection patches.8 X1 Q- R5 G# W8 }: w
  my-column       ;; the column of the intersection counting from the upper left corner of the
, U9 a: n7 Y3 G                  ;; world.  -1 for non-intersection patches.8 R5 P/ H( J" z# ]! M
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" A" @* h( n$ F% Y5 _% c  auto?           ;; whether or not this intersection will switch automatically.
4 ~) M5 z* C% Q1 g8 ?                  ;; false for non-intersection patches.
$ q- D! n* ~6 p' u3 Y9 b6 K4 B- R]6 d% V% Y" T! b

) K; z0 N! {; Z( o0 ]% Q5 D, ]4 Q5 o- S+ A
;;;;;;;;;;;;;;;;;;;;;;
" ~- m- g- ?8 `! n& F;; Setup Procedures ;;
& x9 l1 L( V, M& ?8 B" x; t7 H;;;;;;;;;;;;;;;;;;;;;;
* q0 m& ?( r) D
8 M/ {- j9 ~" O8 s3 B; V1 M$ p;; Initialize the display by giving the global and patch variables initial values.( c! x/ I) G3 x5 _  A; s0 U' M
;; Create num-cars of turtles if there are enough road patches for one turtle to
! w% a; @( |6 s% n/ c& f/ X;; be created per road patch. Set up the plots.+ c+ K1 h8 q) q
to setup$ Q! P: {: U) O# G7 p- b2 F& r
  ca
1 v% [% ]+ u: k0 R  setup-globals
  G7 }# r- l. \' M% C( q1 p+ b7 \+ ~/ n- H& H9 U) D
  ;; First we ask the patches to draw themselves and set up a few variables. z0 E8 ?# y# b/ M7 r& [6 ~
  setup-patches
5 W1 e0 ]$ \  l1 E  make-current one-of intersections
+ J3 X' p. {) w0 X1 L  label-current
. j7 G* X( ?3 Q- ]  _$ {; |, e; D9 C( E$ e2 e, c
  set-default-shape turtles "car"
( e, s% l6 l0 b( g9 s* i& |# ~" K' V& l# q" h7 y
  if (num-cars > count roads)
5 J5 k" O( X: G  @- j, g  [% M0 A  L* f' c$ H
    user-message (word "There are too many cars for the amount of "9 u) P' `9 w+ q0 }: R
                       "road.  Either increase the amount of roads "9 F; U; q, ?: C0 I: {- B% U4 {/ A& o3 w
                       "by increasing the GRID-SIZE-X or "" g3 u6 v2 _/ z
                       "GRID-SIZE-Y sliders, or decrease the "
3 m4 V* ^* H  q                       "number of cars by lowering the NUMBER slider.\n"
$ I, b- e1 A5 L& J& M0 s                       "The setup has stopped.")
* @! [, _% o8 C5 ]3 N( i+ C- y; \    stop
6 n4 X/ u0 u( j- h# H% s# ^" a% w  ]
3 ~$ w/ C. U$ w. P" F8 O* [$ D8 W1 n) y: J
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, {6 R3 T- Q5 c6 s% g# r. Y  crt num-cars. k- D- k5 S2 k$ w) r
  [8 `* n( C! }2 l8 j/ z3 t3 u! @
    setup-cars+ s3 L  N- E4 m6 O$ W: l/ {- M
    set-car-color
. e+ \) J' ~1 R$ E" y& ^    record-data5 L' h; }- \  N* Y
  ]" q5 j* B+ P" y$ \. I

) D( {) |/ P8 G* ^  ;; give the turtles an initial speed  Y9 i1 E" Q8 u; C
  ask turtles [ set-car-speed ]
9 F+ I! {0 c3 }/ a+ R  G. o  D; e2 B8 d& V) P/ Q3 I
  reset-ticks+ [' i  E8 D* Z1 \- j5 z0 l
end. M% R1 E  U8 i

1 A; S4 [4 a) p/ ~7 k;; Initialize the global variables to appropriate values
3 [9 [& Z% @6 J& i7 Qto setup-globals2 [- u: [) a: z; W6 P
  set current-light nobody ;; just for now, since there are no lights yet
( N/ X: ^( d5 N+ w+ T) K6 ^  set phase 0
8 G/ u: S; Q" U  set num-cars-stopped 0  s/ m( q- v% d/ p8 }" v. z  k
  set grid-x-inc world-width / grid-size-x: R. g1 ~% b2 E, \& u' ?  N
  set grid-y-inc world-height / grid-size-y' V0 k# \- r. t: D7 r* S
6 J! D2 o; Q  q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary* e3 l) k7 T0 E
  set acceleration 0.099
  s& d/ z; ?; fend; F# X* D) J4 s( t) t  E) v
+ N: |: D4 ~6 P, r; G6 @! E
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ n" z1 C* u. I9 M1 I
;; and initialize the traffic lights to one setting) e0 g" f' u: `- X
to setup-patches! x( J% e" U6 N4 h
  ;; initialize the patch-owned variables and color the patches to a base-color
* U( z3 `! c3 Q  ask patches
& k/ b( c, X! [5 m- L5 i  [
8 L* E% Z+ m+ J( c* {' C4 f% h    set intersection? false* t8 m" h3 Y0 I* E& y$ d- a
    set auto? false2 Y/ w' W3 c2 v8 R
    set green-light-up? true# b, @1 P  E# T: T6 `+ H
    set my-row -18 ?7 F1 Y+ Q" U  h% E: p. F/ O
    set my-column -11 M& z5 X0 ^. o& Q
    set my-phase -1# H, K4 a7 V; z9 f4 _
    set pcolor brown + 3+ G$ V0 \# {2 W) s
  ]
; w- z5 C0 x+ j
' T6 u* z% |5 X( {( Z/ [  ;; initialize the global variables that hold patch agentsets
/ a, Z6 j& Q+ e! T1 o  set roads patches with% r+ W6 b/ w$ n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ w2 U/ h3 Q! ?) w, b* \4 c
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ H; @: r; j0 p* W" L  set intersections roads with
. _' _5 J) H4 _6 i9 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 O% x% `: H" N( N, E" ]5 V
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
' v0 t  h4 J! ?# A4 a3 s( h4 y4 @7 u3 n
  ask roads [ set pcolor white ]) ]) M& p5 A7 ~! C$ [1 B  e
    setup-intersections8 n6 v# T4 a; Q6 x' m/ u! G5 \
end4 Y4 }5 z7 K/ `# W3 e
其中定义道路的句子,如下所示,是什么意思啊?  P" A* |, z! d
set roads patches with( ~. K, e: H  E6 R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. ?6 ^; Z9 q/ S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# \' X+ [; Z4 Y0 X
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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