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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。) A8 _/ W' |+ X9 @) {
netlogo自带的social science--traffic grid这一例子当中,  b! T2 e% n4 e- m
globals
3 V& e5 K/ u% b1 G! R$ f& A- a[& A4 i/ @" _  |4 h) p1 t6 ]% E
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 ^: N0 C0 A" o  w  grid-y-inc               ;; the amount of patches in between two roads in the y direction
* w$ }- u8 |5 k( s+ i0 s  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
% R9 C. x; n2 G                           ;; it is to accelerate or decelerate
0 n0 ~* z3 t6 ]8 k  phase                    ;; keeps track of the phase/ I  E$ E8 a& ?9 M7 p* O
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# j. T2 @0 F8 N5 r  current-light            ;; the currently selected light, X6 ~; |# I- O! _- [% J
0 T. z' @" C% Z0 [( B# U
  ;; patch agentsets  k, `+ d4 D: H/ V
  intersections ;; agentset containing the patches that are intersections' o8 v3 B1 L) s5 d$ b3 Z$ y7 K
  roads         ;; agentset containing the patches that are roads- e  q+ O) Q9 g" d1 U4 E
]
+ q3 A: ?  z7 Q- w5 I4 A% L7 A1 h7 V, m
turtles-own
3 ~- x- ?& W6 t! Q- P0 o+ N: F5 L[% ~8 m  B0 F% m* ]" w) H
  speed     ;; the speed of the turtle! w! x0 v  o+ U* S, N6 W' K! k4 g
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' r+ N. w% N) h; x- ~2 Q  wait-time ;; the amount of time since the last time a turtle has moved
- u- z" C& N3 }3 Z( Z7 i7 e6 h8 j9 V]& w$ B# [8 L  V9 [1 J

0 c7 W$ a1 ?( p% K4 ^/ K! Fpatches-own
+ I' [$ t2 ?7 @% a2 k) s[, V+ |/ p/ x) m$ N
  intersection?   ;; true if the patch is at the intersection of two roads+ k3 L; i2 Q, r  F0 q
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( o+ K# c1 K7 F/ s; c                  ;; false for a non-intersection patches.& N5 x$ H% L# c% J6 X4 R1 C
  my-row          ;; the row of the intersection counting from the upper left corner of the$ w" K: w. J, N0 J! V  B& P. O9 t
                  ;; world.  -1 for non-intersection patches.3 |  a' I" v/ s  V! l
  my-column       ;; the column of the intersection counting from the upper left corner of the3 u. {# ~4 y, j+ X! t
                  ;; world.  -1 for non-intersection patches.
+ }6 x2 y+ S+ d! b( Z* h3 ?' ]$ w  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ L2 N8 k3 c6 E0 P
  auto?           ;; whether or not this intersection will switch automatically./ L  g4 W. P, M0 i, n/ V2 k* N$ V
                  ;; false for non-intersection patches.% q: t: ~+ _! t0 w
]6 x% f* O/ {3 ~
" S7 y7 f/ t( `/ M

+ U+ V: R' Q. W;;;;;;;;;;;;;;;;;;;;;;
0 V# ~0 B9 r- p;; Setup Procedures ;;# e# {% C; O7 D4 x( U. O7 ]
;;;;;;;;;;;;;;;;;;;;;;
1 |+ A' h& L" B# W: D& W+ x- l# F/ T- M: Z% R% Q, g; |
;; Initialize the display by giving the global and patch variables initial values.
! [7 M9 a8 X0 x( Y- ]9 q;; Create num-cars of turtles if there are enough road patches for one turtle to
. X1 L! [/ a- `, c7 |;; be created per road patch. Set up the plots.' l  r8 |: H1 Q1 A4 H$ `7 }
to setup
+ i- u! W, `( b0 Z  ca
8 u5 E, L9 O& l7 P. h  setup-globals0 _7 ]* J/ e2 d7 R7 L, J; _" A- C) X

$ u: e5 M7 ~" l* a+ L! L, I  ;; First we ask the patches to draw themselves and set up a few variables$ C( O, _8 A8 x% p" p
  setup-patches  Z. }* E0 N, F" W
  make-current one-of intersections. ~( j- t! u9 }
  label-current: K" W3 e& _) i5 ^' A

) S. J. R7 G. L3 C3 e3 d  set-default-shape turtles "car"
# f- ~& F% W1 _" A4 |8 L8 v! d$ m2 O2 I3 I
  if (num-cars > count roads)) \% q3 b- y, C: f
  [
& `  T9 D0 @* I4 d- v    user-message (word "There are too many cars for the amount of ". B5 H& v$ P0 @0 p( F* A# X
                       "road.  Either increase the amount of roads "6 t4 T; D: J& \- A* `
                       "by increasing the GRID-SIZE-X or "
# c  U9 u5 b6 r& ?$ c* P                       "GRID-SIZE-Y sliders, or decrease the "% V+ J5 I( m- ?, a) w: d3 @0 N
                       "number of cars by lowering the NUMBER slider.\n"& _/ k" G$ g$ G  d0 ~
                       "The setup has stopped.")
" r# s* ^* D6 j* t7 p1 f% O& S    stop' _0 E1 v4 d% y* P2 s+ N% N8 [2 R
  ]
! j# Q2 q1 W5 V% o& J% n
( c$ V2 R+ j+ E" D- C. Y9 s  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color3 M  F2 r+ H" x# s3 s
  crt num-cars
9 _$ @0 U- ?$ I/ N  m$ A7 B0 a: n  [
. _4 a" a( y# E9 m" V/ k9 E' E0 p6 Q    setup-cars" f3 j  V9 B7 B
    set-car-color
& K$ a+ B& C; n4 |8 P" Y4 I    record-data# I' [/ e1 u$ j2 a6 v* x
  ]) W. \, f- o+ s8 o3 a& \; z" Z
8 I7 D7 q4 k# @3 z- m
  ;; give the turtles an initial speed' A$ \1 E7 ?2 n$ J! Q
  ask turtles [ set-car-speed ]
* l2 E6 l: |; g
% \/ Z% A1 C' @1 p1 D) J2 M  reset-ticks
8 _5 M* i* H, S( J! q1 q6 `3 @% ?end
% u/ z1 R: H; x. X& X6 I& C: G$ P. F$ \& {
;; Initialize the global variables to appropriate values6 E: p* u/ k4 C% L* i
to setup-globals
" ~( H" V+ p. V: \4 s  set current-light nobody ;; just for now, since there are no lights yet
( [# C2 @# B' t# B* n  set phase 05 }+ R' i' ~+ j+ E/ l
  set num-cars-stopped 0
5 U3 ~; r. c( b) O7 ~  set grid-x-inc world-width / grid-size-x
, X$ h: q. j0 I8 T% R# L9 v  set grid-y-inc world-height / grid-size-y
* C3 P* R: R4 Y! q7 w/ A) s3 R7 B4 p! `, i% }' A
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary+ w- a7 l, s4 h2 a
  set acceleration 0.099
. G/ G! U" ^6 |# qend& {. d; |9 f3 q9 e
  R$ S) b0 r6 i& U/ L) A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) T" @- \2 P) a4 h, r# X8 C
;; and initialize the traffic lights to one setting' j) O; ^3 m, u; K
to setup-patches
. H, \+ a1 U( j  w$ q  ;; initialize the patch-owned variables and color the patches to a base-color9 q7 W4 X% L. A4 `. B2 x4 Y
  ask patches7 X! x6 y) Y( N! M- u9 e' n) `
  [
6 |2 x5 x1 k8 n) z/ M, h    set intersection? false
- f, S, ]7 b) e* v8 a" K' g3 n    set auto? false: U" l8 S) S" r; C
    set green-light-up? true1 |3 _2 J4 j* R3 J& e6 _+ @& w
    set my-row -1- g- `% C1 G3 c8 i
    set my-column -1* u; |( [8 S* Y; m
    set my-phase -1/ @2 R/ J) m3 ~- V
    set pcolor brown + 3
  B. v0 }( d3 \  ]; x; S. P# G! K) p4 `! }
2 Z; B9 P2 a' h; U
  ;; initialize the global variables that hold patch agentsets$ b  x" ~, B0 M
  set roads patches with6 l% S; c# ^* |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
9 W$ k9 ~% c$ b; l. d& y# ~8 \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  ?& ?% Z  K3 m
  set intersections roads with
4 W: u  P; k% n3 a7 ~" H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and7 o6 i3 k* s1 |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% n) [8 M, D# @1 D0 N, X: G. X2 o
5 C# Y  s2 J' y# [2 z3 i
  ask roads [ set pcolor white ]
4 n1 E/ K2 d: X% V$ Z' t+ t- `5 f: K    setup-intersections# ?5 |7 C, d; _8 \$ S, Q$ c2 j$ ]2 m3 U
end
6 P5 ]' N2 |* z) g4 O, J其中定义道路的句子,如下所示,是什么意思啊?
) s$ n* |3 A6 i3 R! m. }. @8 g set roads patches with
# _/ E0 I/ \4 H( Q% h7 U3 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 Y9 @& T2 c0 Z. A1 L
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 v. _0 w6 @& ]( W! l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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