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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。
) y) K0 |) d& N. o; fnetlogo自带的social science--traffic grid这一例子当中,2 n# e/ k  \9 _9 r# q. Y& ]
globals
/ B  \3 F3 l: L! X" ][
  j/ L; L. e& u! E- r) q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
) w8 G0 x' W# j5 {- B  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 U0 M3 N, O5 {  B7 F; v  acceleration             ;; the constant that controls how much a car speeds up or slows down by if8 z& V0 B' M0 ]8 }0 F0 C
                           ;; it is to accelerate or decelerate: c# s  k& ~4 |% A) k
  phase                    ;; keeps track of the phase
/ w4 ^0 v3 N" l4 G, _, I- H  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* \( r: Z% O1 Y/ J6 q" d0 ^
  current-light            ;; the currently selected light# ~, n0 J4 W  _4 \4 X3 k
# p" N* P3 }3 l; W( G3 l; t
  ;; patch agentsets
6 j1 B( \. t) B" N. E; [  intersections ;; agentset containing the patches that are intersections
. [: W, A1 }! @. s: W; T; r' A; d- m  roads         ;; agentset containing the patches that are roads$ l; Z! \6 r  k- J
]7 K, {3 V. s4 u# ]2 L
( |$ G$ Y7 y+ s" U6 U2 {$ h
turtles-own# Q2 k2 h/ }& W' x, T
[) ]: j/ E$ e  w4 L0 Z
  speed     ;; the speed of the turtle
5 L- \0 `3 K" y( ~& x  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& L& n+ v# K. A& \) L  wait-time ;; the amount of time since the last time a turtle has moved
+ y* e. s, _+ \9 e/ O% _8 [. e) K]- O1 z& n3 z& q5 t2 s
. r- [7 D2 j* E) c/ L. y$ B
patches-own
/ q4 b% m9 l1 t$ Q6 M3 L[, x- `+ K" p/ p8 f
  intersection?   ;; true if the patch is at the intersection of two roads; y/ G( W7 T4 M& M, P8 U% U
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
: p  ?: C. o* K- d* \! ^                  ;; false for a non-intersection patches.1 m/ B3 f( d& a0 f/ V
  my-row          ;; the row of the intersection counting from the upper left corner of the
5 H( M7 B" l% Q8 \+ o                  ;; world.  -1 for non-intersection patches.
/ x( Y4 x9 `/ G  `; e) J' M$ e  my-column       ;; the column of the intersection counting from the upper left corner of the
% o7 v$ L: V% P) g7 E1 X* ^                  ;; world.  -1 for non-intersection patches.
% t' t( c: y* O  }& d  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ V5 d& b- F! z6 N6 \. `  u4 Q  auto?           ;; whether or not this intersection will switch automatically.! U' k/ W9 _4 |7 [, V
                  ;; false for non-intersection patches.7 X; l" e. Q/ G% ]1 J+ U
], j- I5 w: c  z  l! O# I( L) c; Q
4 @# J& ^8 Y! C: Y7 N. Z- o

* T7 j+ A0 O: M;;;;;;;;;;;;;;;;;;;;;;$ T+ y: d/ t8 Q) h
;; Setup Procedures ;;
1 R. ]6 E* \- A) f* r9 X;;;;;;;;;;;;;;;;;;;;;;
8 q" U% t2 z- r
6 l: }/ A* G% I  w; u: S0 A  e;; Initialize the display by giving the global and patch variables initial values.
8 {' o1 {% M' X$ c7 a;; Create num-cars of turtles if there are enough road patches for one turtle to/ ?0 \3 u9 }* ]. T, o4 H
;; be created per road patch. Set up the plots.
( y# J# I; R/ Q% kto setup. M# d; t# k/ H+ _; G3 w3 ]
  ca
7 F; e* U% t% T  setup-globals# l( ?  k& ^4 h- ]

6 r3 G+ _& v, I, ~- w: s  ;; First we ask the patches to draw themselves and set up a few variables5 i7 ^  Z2 V: k$ M& t
  setup-patches$ y" v3 }; Z% ^. F8 w( u
  make-current one-of intersections+ ]5 Y4 p% ]2 N+ a/ m9 k
  label-current
" |/ c; D7 S6 ]' r
: g& L1 B0 o/ j; k1 T& Y2 {# C" @  set-default-shape turtles "car"/ N5 I- F$ W& m% H' s
" `+ P) n- X( l0 @2 s9 Y
  if (num-cars > count roads)
6 L0 }/ Z9 ?/ m. g0 f2 U  [/ q+ k* ]7 F" I  L
    user-message (word "There are too many cars for the amount of "; k5 h9 R! Y4 r- a" B
                       "road.  Either increase the amount of roads "
% a* N; }! `* c8 B+ a* A3 r                       "by increasing the GRID-SIZE-X or "
. ]6 I- `$ R0 z5 l9 Q5 E                       "GRID-SIZE-Y sliders, or decrease the "
. g$ a- `, a7 L* |4 |/ A                       "number of cars by lowering the NUMBER slider.\n", e) S' [+ {1 H+ Y4 {) F
                       "The setup has stopped.")
. M' g, \' g4 ]: n    stop; ~6 m% j3 S- M. @5 [5 K
  ]
- p; @/ ^$ q6 E$ Y$ V
  s. k. A- [4 f  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" c" W2 Z0 ^. ~& M6 C
  crt num-cars
3 A- T; s4 Y. y3 N  [: r3 M& g/ h2 f+ G+ v8 l
    setup-cars
. C; J2 s9 h( a+ L    set-car-color3 I# K  r# R, N) O5 b
    record-data
" }. N+ @" C0 ^7 R  ]
  @2 ~5 ]% W" e8 D3 D7 S3 Q2 z, Y# ?1 [* h
  ;; give the turtles an initial speed
9 m6 u3 p& S+ n5 J  }' q  ask turtles [ set-car-speed ]
- \' Y0 s# p  f5 y3 F# ?# U+ t
  reset-ticks
* e1 j* p  b' send( O' F9 z' U% K1 v! t

7 z% u/ G, x7 q9 b- P1 G; o;; Initialize the global variables to appropriate values4 c: O1 Z  P& A
to setup-globals( {! n5 b% @( m1 ^9 c5 k  S4 l/ P
  set current-light nobody ;; just for now, since there are no lights yet3 r5 _! ?) n" j* `' j) t
  set phase 0
8 D1 R! p5 f* q, d  set num-cars-stopped 04 H% @) @0 m1 h- _8 p
  set grid-x-inc world-width / grid-size-x
8 y' v! Y' `  ^: z; f5 v4 `  K  set grid-y-inc world-height / grid-size-y
+ w( P+ m# B) y/ {. R7 n- S4 Q# ?) K" F: G! T. K% R: q* v
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 u8 D' @9 k/ M( U  set acceleration 0.0991 \" Z1 ^$ ]/ Q: I3 I- u
end* p' y3 d4 Y8 i0 ^' t

) j6 O6 x( _4 |" o  [;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
$ S% z$ r9 R3 u& g3 y$ F8 U;; and initialize the traffic lights to one setting
' H: x5 o( V9 \# Uto setup-patches
3 X* c6 y5 n: `: M# l& l9 |7 m  ;; initialize the patch-owned variables and color the patches to a base-color
7 W" a% n4 H* z/ U9 {% n% H7 m& I/ `, M  _  ask patches
" d# D1 T. \) T0 s# W  [
5 W7 x3 P4 _( |) O6 d# o' y* s    set intersection? false  I( e% |! h6 i$ H' ]
    set auto? false. R/ `( R: U6 _
    set green-light-up? true
/ ?2 I8 A- Q& z3 [: D/ m8 @    set my-row -1, b3 I. L1 ~% U6 w* H& R/ X; i; X
    set my-column -1: K+ L% e' l% k9 w4 P. c, Q: O, Z
    set my-phase -11 A( P' `+ D: S3 C
    set pcolor brown + 3  P7 ?" z  Y2 S
  ]2 W, Q4 H5 B* @: c- G8 J: p

# r7 c" F' ]5 W  h9 O+ v  ;; initialize the global variables that hold patch agentsets
- l2 b% p3 I) H$ h/ `1 z7 A5 j  ?  set roads patches with
' i+ e* o# ?2 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 E- S; c! z+ O$ C. J3 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 b. o. z2 _/ R6 M$ s( r( ]# P  set intersections roads with6 o& y$ P7 A9 y9 A1 _3 |9 S; C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
: m3 p( [  w- c1 K3 H2 z    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: m) ^2 D- H. j" H# }6 s

3 K- ~  f- f# h$ Z) ^  @# w# y  ask roads [ set pcolor white ]
' L, K1 t3 P5 P0 k+ J3 q: G3 l( I- z& V$ K    setup-intersections2 I6 C+ \) o+ N! ], v+ o! r% e5 s
end
5 u: M" e, O4 E7 b8 F8 g' A其中定义道路的句子,如下所示,是什么意思啊?) J3 ]# o' S  P
set roads patches with
2 e- z7 O. e5 g! `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
% r, |2 ?/ Y6 Y$ Q- A4 u    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' ]  }, b+ ^- h  F* v% G8 ^; t
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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