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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。2 H( s, ?" J% p% X: ~4 X
netlogo自带的social science--traffic grid这一例子当中,
7 t- ~; N) Q4 C: jglobals
0 M6 w) Q& l# W  U$ b7 |[: Q" g, ~7 q$ G
  grid-x-inc               ;; the amount of patches in between two roads in the x direction5 x, G2 q" ]! g6 h9 A7 I
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  V7 l; r1 Q; q) w' o  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
9 t% t* T7 Q; c3 V/ |                           ;; it is to accelerate or decelerate( B& K5 N7 \& h  {! ]( o* \1 v
  phase                    ;; keeps track of the phase- R1 J/ s' z) A9 W* S/ L" B2 x
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
  ^+ H1 \& q' A6 v  S! h  current-light            ;; the currently selected light: o, o. W- i6 P+ j. I5 o
' B" ?9 E" X3 D6 N
  ;; patch agentsets
/ P- N% P; u" w* F  intersections ;; agentset containing the patches that are intersections
! J( P3 z6 W. U, H  roads         ;; agentset containing the patches that are roads
- M' E5 n- S% ^- f2 ^6 u]
! S, ?  p6 I5 |: d* d7 w& j) H, `0 D0 I/ \
turtles-own! r" M- l4 E$ f( u+ M
[) y# y) c+ z. s& f1 H
  speed     ;; the speed of the turtle' X, o/ r7 [4 F3 ^/ Q
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 D  s1 d. w8 s) W: X: J! i" X" S
  wait-time ;; the amount of time since the last time a turtle has moved5 P# o- _+ J% E- R' k5 F
]- F' j( W* T. v" g! _" \% Y1 e; J
( Z  V( ~, f7 J( o' m+ b1 c# w
patches-own; W6 Y3 i- _+ |0 x, m! z# S
[1 o: N5 r: p$ m* ~' b6 v
  intersection?   ;; true if the patch is at the intersection of two roads7 b) H/ E& a4 d) W3 K4 j
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: X6 p! I+ D3 o9 o
                  ;; false for a non-intersection patches.% V3 x5 D$ w& c5 Z4 K1 G0 [
  my-row          ;; the row of the intersection counting from the upper left corner of the
( L9 Y( R$ O" Y( J' c- P$ u                  ;; world.  -1 for non-intersection patches.
! s# Z! g  Z1 J; Y. N  my-column       ;; the column of the intersection counting from the upper left corner of the
- u* v0 Q! s2 Y3 k5 G. M; c) d                  ;; world.  -1 for non-intersection patches.  r$ l, ^/ A* o$ r/ Y
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.  S3 H* U+ s/ ~" i
  auto?           ;; whether or not this intersection will switch automatically.2 @, v% J0 R5 Z; ]1 E
                  ;; false for non-intersection patches.
! L2 S) D" `$ m9 C* D( F" ^- F  w]# f( G' H& d' ^( ~2 Z/ ?: J. P
4 W. a: k; |; H( P' w

3 v, l2 m1 p2 z' O& T;;;;;;;;;;;;;;;;;;;;;;
) G, R9 k& a; e/ P. N/ P" B/ s;; Setup Procedures ;;# j1 S5 s, n8 {
;;;;;;;;;;;;;;;;;;;;;;
1 I( T0 H0 `* {* o; `4 d: E" s3 S) n6 z. q
;; Initialize the display by giving the global and patch variables initial values.: }+ G0 \2 m2 l
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 u( v1 D! ^4 g. M6 S;; be created per road patch. Set up the plots.1 I" E) O* x$ x( D# u
to setup# r; F# w; u' i. s" E0 r2 x
  ca
+ i/ e& ^3 a9 A( f$ _: k  setup-globals9 s% `3 P- ~' m( f# k4 r7 @
4 L  C  {; O( U7 t  K$ @
  ;; First we ask the patches to draw themselves and set up a few variables
- q8 ^  W7 W, q4 x! S  setup-patches
3 l. `4 Y- o, t  make-current one-of intersections
% T9 D: h4 D" p  label-current
( f" {$ ~. p* u5 y
$ u( E+ h$ M5 g# s3 N4 c: u9 Y6 H3 B  set-default-shape turtles "car"
8 c/ c% [# c" X/ ?. V: q) P- n
0 t" z; e9 {1 k1 y' e3 i" Y  if (num-cars > count roads)
3 F" e' N, ^: ]% t" L  [) g9 L. V8 s; j; ~3 u- F& ?
    user-message (word "There are too many cars for the amount of "
4 X1 F  P* I# O. D* n0 v4 X                       "road.  Either increase the amount of roads "2 C. m& O5 O6 H: U3 i* y9 z
                       "by increasing the GRID-SIZE-X or "
1 O9 u; U1 ]6 \                       "GRID-SIZE-Y sliders, or decrease the ", a# A1 I9 h5 z5 x2 F" W. z. Y7 T
                       "number of cars by lowering the NUMBER slider.\n"/ M# Q$ k- I0 @
                       "The setup has stopped.")8 X- {$ n& P( k
    stop
2 h" A' u7 g8 L# o; E1 B; K  ]% u3 ?! F" i* I9 Q7 T2 O1 X) Y# l

/ w! L; ?4 Y8 D  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color7 ?# b* b6 v, ^$ [* g
  crt num-cars
% t( G4 a  h* T+ q' Q8 k) N1 E  [  A! V, o: U3 a; n
    setup-cars
, K# _, m! Z6 k- O7 M% p    set-car-color
2 W& ]' x5 C2 d. R" t    record-data" ~9 r5 X0 F; p2 u9 w& C+ f
  ]/ _$ p9 r* ?. p$ p

& z9 H3 I- d  O0 b( z; D2 {. y  ;; give the turtles an initial speed
- G' S& K6 |' b$ S" U  ask turtles [ set-car-speed ]3 Q( g* p0 s# q' p, ~$ ?2 Y- H
, C$ R1 d/ K* I$ n/ f% D
  reset-ticks
1 z6 o2 \2 s! T( R$ fend9 s9 p0 J/ @: w* g: Q- i. Q6 [$ ]
2 y- ^! L- R" q* j/ a5 b1 m
;; Initialize the global variables to appropriate values
: j) y/ U3 d0 t4 B2 A4 A2 e7 rto setup-globals
5 p' [: K, Q7 M7 x; N  set current-light nobody ;; just for now, since there are no lights yet
4 B- ^5 S: k3 S( Q1 C* P% N- A  set phase 0
( I& t8 }& L' l  K6 _  set num-cars-stopped 0
4 q- u- {2 P3 w6 Q  set grid-x-inc world-width / grid-size-x
' Z$ W* u. d. ]  set grid-y-inc world-height / grid-size-y8 M, C7 j7 N$ R$ E6 b
8 }# m2 Q' s; s1 a5 I4 i0 x: R" y
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ e# w! z) z  g5 z" c! ?, a
  set acceleration 0.099
& X: M) {, |8 X/ Tend
( z9 |' J' m' E8 ]$ e4 G* `; E5 i0 {$ d% s- B/ `
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. C) ]$ V4 [$ L# Z$ D
;; and initialize the traffic lights to one setting
: u( \3 e3 Q- k- l* B  U. Fto setup-patches1 q' n, b: S/ m: @
  ;; initialize the patch-owned variables and color the patches to a base-color# Q9 R3 m3 d. N; S+ ~3 `" m
  ask patches
/ z* i0 \3 u* i( q) n" J- `# K  [
" n0 t2 r; d' W. s    set intersection? false
/ d) P! N! ]* y9 O! E5 H    set auto? false( ^( S* r' }% g% D+ x8 |. y% C
    set green-light-up? true
& ?$ B+ w) Q$ f3 U5 p    set my-row -1
+ u" S% R+ e; i% G3 W    set my-column -1
. O$ P  G  }8 ]# m3 ^( g( c    set my-phase -1
' V+ I/ J9 d2 k( }- P    set pcolor brown + 3
8 }" V. i' [+ @  \/ c& f  G$ l* M  ]
3 H5 A# m" e+ |  y0 D! r% a
7 ]- @0 E: B, |; L  h6 I  u) Y+ y9 e  ;; initialize the global variables that hold patch agentsets( _) X3 {  v6 S
  set roads patches with
+ ~0 D* S% @: x# R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: S7 X3 h: u. d" v/ x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; _# W! w" J8 O
  set intersections roads with
. O/ ~9 S, s7 Q" Z1 ~' o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and# m# y- j: ]8 X1 F5 E( Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 U- }. S, e/ i. n" C; a; C; q% U& k# V, G
  ask roads [ set pcolor white ]
2 \& b' Q6 c2 Q' T: j4 A$ g    setup-intersections2 M% o  j1 O  c1 ^
end+ I7 l2 F. H3 }8 _+ D' G
其中定义道路的句子,如下所示,是什么意思啊?
9 F( w: k* P6 i6 [5 y' H, d# } set roads patches with
, M7 V/ w" x6 |: v, M( t/ ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 h4 `( Q% }# F- C% j! j: x
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; ?/ @# e8 a3 L1 u" d3 C
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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