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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。4 H6 n3 B4 {% ^7 _( Q4 |
netlogo自带的social science--traffic grid这一例子当中,+ L/ a) A+ `2 q7 x8 x- y* d5 u
globals
( [1 t3 S+ k: @1 ]" y9 X9 W1 r[1 _: }  [( L7 Y' o
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# \3 y# @- j' R' K; V: T; g. m  grid-y-inc               ;; the amount of patches in between two roads in the y direction
2 N1 K- D7 P5 w& r  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
/ ?1 u% X0 h# Q! s! t                           ;; it is to accelerate or decelerate
5 i" U% @- Q& |7 H" y; O5 k  phase                    ;; keeps track of the phase+ c7 ^/ s3 \6 ~  i
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 \/ d1 c8 }2 W" `  current-light            ;; the currently selected light
7 _3 j1 l0 D* Q2 m/ `$ R' Z* y+ @$ B' h2 `$ _
  ;; patch agentsets
" I( {' p3 g5 i2 j# I* ], k' S- r  intersections ;; agentset containing the patches that are intersections
" D' t9 h9 [& J( \, V( j8 e' _  roads         ;; agentset containing the patches that are roads/ @7 q8 y: o; J' b) z
], K" |4 _+ d. `8 y0 k

& n8 m! x) m/ w( M; C2 P& L& C, ], Q0 xturtles-own
6 T9 c2 l  b3 h; J% f[
& q( ^, C7 l3 p  speed     ;; the speed of the turtle
* y2 [. }  [' P9 m, @  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 y) C; O& T) M4 `  wait-time ;; the amount of time since the last time a turtle has moved
6 M  d# }1 c3 f+ `3 |8 j]) Y+ z- ]9 T1 E% ^

7 _# B& `: m: }patches-own
# o4 e  C( P$ ~. Q4 ][
- ]2 x" A/ k0 \- y: F2 W: H  intersection?   ;; true if the patch is at the intersection of two roads
0 S8 p& Z  J0 `. A( X. p. L  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.+ ]2 _) R1 a5 W5 X3 b3 M  r
                  ;; false for a non-intersection patches.% ~4 e: A3 B5 b; [4 C2 _
  my-row          ;; the row of the intersection counting from the upper left corner of the
0 n  c2 Y) N$ {2 i                  ;; world.  -1 for non-intersection patches.+ M$ V$ e% h6 h# T( v6 y& y. g  b! Y9 y
  my-column       ;; the column of the intersection counting from the upper left corner of the: E- {& t9 ]) d, W
                  ;; world.  -1 for non-intersection patches.
& R4 ?: W, _8 m2 r, g2 }5 g! e. X  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 m3 k5 f: l+ ?9 q  auto?           ;; whether or not this intersection will switch automatically.
  J) F& g6 S. ?5 d+ U* w                  ;; false for non-intersection patches.
5 f( I6 V( n; n, Z; s  e- i]
$ s- b# H; R: J/ r# I. y8 Z" v$ f/ f7 j4 z+ `3 A
! b! D' ]4 q# V" w9 T
;;;;;;;;;;;;;;;;;;;;;;
: I( ~8 t, p' i4 K, e/ X) x;; Setup Procedures ;;' X1 @% X1 B7 K) \4 }6 c( k# L" i
;;;;;;;;;;;;;;;;;;;;;;' F1 t3 H3 O1 D$ a' L

, @, t1 v8 ~. L/ a! v;; Initialize the display by giving the global and patch variables initial values.1 H1 \% r+ L5 d
;; Create num-cars of turtles if there are enough road patches for one turtle to3 `$ Z7 L+ C+ Q+ }1 \
;; be created per road patch. Set up the plots.5 Y3 {' M* _) a. z4 V, \% p
to setup
- S5 {3 l) `/ ]* p' U# C) o. W  ca% x' {, d. y5 W. p4 a
  setup-globals( Y! R0 `/ g* }* b$ t: j
! u9 D" n. p- |$ l
  ;; First we ask the patches to draw themselves and set up a few variables' W4 |3 L% o/ v  d, m9 v
  setup-patches
" t) W5 b6 p" A. e  make-current one-of intersections
9 b& s& d" r, A; M  label-current& Q6 s* L& p' B+ S4 L
9 r) E; h) |& ]+ E
  set-default-shape turtles "car"
9 [+ u& A0 D  O- f8 n# h) B4 Y+ I; [! a- V
  if (num-cars > count roads)
9 Z$ l/ N3 s! v' J( s' h9 {) V  [  B$ ?! T: U$ |4 m6 X2 o, U
    user-message (word "There are too many cars for the amount of "' k1 V+ r" d# w3 k9 w0 [5 B
                       "road.  Either increase the amount of roads "
& h) P, J$ g4 K$ }6 @                       "by increasing the GRID-SIZE-X or "
% q# }0 |) I9 _* x/ o4 x                       "GRID-SIZE-Y sliders, or decrease the "% a9 H( D5 d( @1 o7 u
                       "number of cars by lowering the NUMBER slider.\n"
$ M1 z4 h- R1 T4 {! I( U- p) I2 |                       "The setup has stopped."): t# I. g1 c" k4 C4 J" u5 H
    stop  f; p4 K! }( N+ y
  ]
1 A+ P% R% {$ W+ C
0 |) n5 F* {$ W' P  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
1 y/ E: Z# V9 c6 M3 Y  crt num-cars9 p; v9 e. H% Y
  [* {' z8 ]4 ]4 T; }, x# N3 r
    setup-cars: a1 Q3 S$ a+ {
    set-car-color; w4 i( K, j- T+ N
    record-data
+ S) s& R/ m3 X  ~1 O  ]
# D8 u8 y% A' f4 Z3 z/ K/ R5 ~( l$ \! {7 C! i! M8 J7 w
  ;; give the turtles an initial speed
7 a% H2 k5 A  ~, Z. }9 \# X  ask turtles [ set-car-speed ]
( U" u% |: n4 B5 t8 Q) S( K5 T$ t7 r, ?+ D) n. ?. k( k) K
  reset-ticks
2 Y2 {. u; P6 U( ~. O$ y8 lend* w% ]; t+ M  n+ Q0 g6 q
1 z* I- I  z& s& b
;; Initialize the global variables to appropriate values8 y, R- E  U# x7 p& D. [
to setup-globals$ C5 k& o4 m( x; N5 U# g6 F7 x
  set current-light nobody ;; just for now, since there are no lights yet4 a5 R- v) d3 C% ]; R
  set phase 0
! J1 V, Z- i% g/ g3 H  set num-cars-stopped 0/ c4 D, z& v4 y! E: B( M, `
  set grid-x-inc world-width / grid-size-x8 G7 j6 d4 Q! F, m: w! D3 E
  set grid-y-inc world-height / grid-size-y& x, J, P2 U7 M7 f; L9 f' `
. Z4 Y9 t" v9 ~6 t; `  u
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
: F- c: O4 l! z3 v; I  set acceleration 0.099: H0 i# H5 Q( m" _
end+ w4 x) x, C! Y. n3 F  H- Y. x
" F' G: E# ]# }2 g( g9 X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 l' B6 l: g7 q0 h
;; and initialize the traffic lights to one setting
" V- \" Q' k& k* F/ V, tto setup-patches
3 ]7 W8 M3 {/ ~  j2 M+ d* S+ y/ o  ;; initialize the patch-owned variables and color the patches to a base-color
0 R1 a7 d3 [/ U9 i( u' c  ask patches
, p) `" j/ o  n/ `  [3 @2 |) k- }& N6 C+ [* B. u
    set intersection? false& Z+ d+ J6 o6 U; u8 k8 z5 l% W
    set auto? false) U# L, P, q2 k5 k% l, `; X$ ?% P0 Q9 T
    set green-light-up? true8 s! o, `9 @5 N& @; h/ L! _+ C# g; G
    set my-row -1
4 L; t. ~: _5 x* R$ D6 D) [( S    set my-column -1* m" g- Z& c; v9 j; b2 x
    set my-phase -1
7 l  N) ]3 \& h! n# S( z7 [    set pcolor brown + 3. n0 o0 U, T& C- y) }1 N
  ]* U. C% }; w) G4 D6 i) ^
7 p2 N( [6 _! U( T% |' C2 G# B
  ;; initialize the global variables that hold patch agentsets
, k. z# c* p* a. e/ |8 n% h; L  set roads patches with
: O+ ~9 V" F9 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) _9 U" [, N6 H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* _4 v+ r( X6 P  M2 \
  set intersections roads with
4 e4 l# Q( [) f' ]* M    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and! m, A  `3 Q3 q0 j5 m
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) W& M* v0 ]$ p& T6 W2 \" l, L/ h: ]; p! W( C8 N. d6 d
  ask roads [ set pcolor white ]
+ `3 U. w7 n3 G$ D4 u$ s1 h, V8 ?' R    setup-intersections
0 [0 C, g8 V7 jend6 K$ ^/ w" R% A
其中定义道路的句子,如下所示,是什么意思啊?0 w! |, v5 A- }. G1 ?
set roads patches with
4 \* n. e" }0 ^2 c' A1 @1 U* k2 `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 J6 e2 E# A* V! a$ q* p! w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 h' _$ E7 b' m. m$ U) A. @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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