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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。  [* n, E* C6 q& B" X
netlogo自带的social science--traffic grid这一例子当中,
$ q: _2 j; z6 h! n! m. Q. [globals+ L% R8 E& t- L5 e! Z  M
[
2 U) A& M2 W3 W$ r  [  grid-x-inc               ;; the amount of patches in between two roads in the x direction& N0 G0 E2 s) \( h
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
" w5 \+ I# f# ]3 Q  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 W# p9 h9 n' t6 ?4 H                           ;; it is to accelerate or decelerate: G1 p- ~- i: `# O
  phase                    ;; keeps track of the phase6 b+ D! z5 ?8 p  h7 K
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. _3 K0 w3 }) D7 g
  current-light            ;; the currently selected light
2 G& s% k0 P; n0 s
4 z1 M1 h! j7 {. L* K/ x  ;; patch agentsets
3 C3 C& n# o- G: V0 s  intersections ;; agentset containing the patches that are intersections
- p  s, ~" S3 T' M4 c  roads         ;; agentset containing the patches that are roads. X- o# |; k6 v9 }% m8 w2 ~& G
]6 z9 c9 X+ @; g4 n( k3 O
, y+ i$ O0 B$ l5 x  L
turtles-own
" \& K1 x  A' e! Q) n/ k[  X2 |) E+ d! r6 O3 s
  speed     ;; the speed of the turtle
. \$ G, ~/ P" w7 \7 [  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 r& y3 {6 M7 S$ m8 E' X  wait-time ;; the amount of time since the last time a turtle has moved! t$ h: V4 N! f" e3 K
]$ u1 I; d3 g) [

# z( S% I5 s$ v+ D/ w; s$ G* Kpatches-own
9 Z; T8 P% G' J/ o  D- m% n; y[
/ u; R' R5 j: J4 _5 J8 K! w$ p  intersection?   ;; true if the patch is at the intersection of two roads$ g' ?, ?) p, ?- ]7 S: x
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.9 N* _& e3 d& t* x) p* c
                  ;; false for a non-intersection patches.0 j- Y5 \5 q  N; n% T$ f# w
  my-row          ;; the row of the intersection counting from the upper left corner of the# F7 T, I1 y& ]& K) V( R" v. a; ?
                  ;; world.  -1 for non-intersection patches.4 A7 Q7 ?7 n  E" J/ y6 J
  my-column       ;; the column of the intersection counting from the upper left corner of the
5 }  m# @( i5 v( f, R/ K) N5 ~                  ;; world.  -1 for non-intersection patches.
: e. R( w1 B" M# m" n. `' J  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
: m  y# ?+ K" C" n- d9 |  auto?           ;; whether or not this intersection will switch automatically.
  p3 D7 K3 o. k5 j9 o# c8 b                  ;; false for non-intersection patches.- y1 L7 B$ \* H6 ^% P
]
# v) f* B: p1 S' C; v$ {
1 O! z8 {3 n. S! ?
- e* x' Y/ x  Y# f% M;;;;;;;;;;;;;;;;;;;;;;6 @) S( N- u9 \- f7 ?
;; Setup Procedures ;;6 \4 S; v( \) s6 X
;;;;;;;;;;;;;;;;;;;;;;' ~/ m$ c( N: [2 u! m
6 b2 @0 o; w1 e- I/ Y; M
;; Initialize the display by giving the global and patch variables initial values.% w# J% Q, \# A3 M& |) O0 b+ n' d
;; Create num-cars of turtles if there are enough road patches for one turtle to
) O/ C7 @5 V5 T9 s;; be created per road patch. Set up the plots.
# N( v8 B, ]: _) [; H9 J- mto setup6 \( ?* R. g3 R9 \* T
  ca
9 Z8 c$ f& |9 d5 z" b" g  setup-globals
7 {, j+ C2 K' F) C. ?: z# N4 X) o& Y" E: e: E. ?5 M
  ;; First we ask the patches to draw themselves and set up a few variables
& |2 j) |% R- J) i' Z" O4 H  setup-patches+ v% G( s5 b8 K
  make-current one-of intersections9 {' x! C. P8 h" y  T2 R2 m
  label-current
# A7 W9 _  D/ [5 z' D) H2 B7 ?
7 l) v6 Z) w) H0 j" p  Z  set-default-shape turtles "car"
& {2 S9 b7 N0 y8 ?; d4 n. H: G9 `: I+ H* B$ \! M% S
  if (num-cars > count roads)( _5 v& `* K2 ?+ h0 L) \0 G' ?4 n' g
  [
5 E! r6 x* A" d1 ~) Z) C    user-message (word "There are too many cars for the amount of "
  g% a/ E. d' }" ?                       "road.  Either increase the amount of roads "- [5 _' O' V. l5 Y
                       "by increasing the GRID-SIZE-X or "# F( @* e! a/ u1 z6 E
                       "GRID-SIZE-Y sliders, or decrease the "
5 `  N6 i7 x2 d3 y: X                       "number of cars by lowering the NUMBER slider.\n"( w, t' G  U2 d# h; h# R
                       "The setup has stopped.")
1 v7 n6 M% M8 Q7 o6 }1 b! _    stop: F5 A) s# y0 n' c: ~" J  z
  ]7 B/ @6 _! s: u! P  Y5 g
7 C7 a8 f+ `( N5 A, [
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color; w, F  s* p  U3 `
  crt num-cars
3 i6 S( r2 u# g8 }. \  [
& G" v: \! i1 I' V/ d    setup-cars
2 H; }: j) y1 b: Z2 y  U: g    set-car-color3 O! n; U5 a6 I' ]5 F7 s0 t5 h0 n
    record-data0 o, l, ?5 T& P" y6 c7 O
  ]# n) V4 `2 t0 `+ C* }
" B  z9 y9 K, B: _3 C
  ;; give the turtles an initial speed
$ v# i( q/ m5 H  ask turtles [ set-car-speed ]2 O  ^( k! S( z3 C: d# [

+ _! o% v- }/ \! C3 [4 V  reset-ticks9 f0 V5 h) B+ r  t$ n7 T
end) C6 X  G2 R7 b" `  Q7 k3 ?( {) e9 ?
7 t1 Y' d- T2 D$ {* {6 T' ?
;; Initialize the global variables to appropriate values
1 b. m1 f( s0 }' X( v, z' zto setup-globals0 a! f' n# u* s$ Z! p& p$ z: |1 s
  set current-light nobody ;; just for now, since there are no lights yet
2 m5 C" J) |3 i! \; x  S  set phase 0
' b. u* y; i; w' n2 Z) E# _% a  set num-cars-stopped 03 D, Y/ Q. x. A3 p7 ~7 p
  set grid-x-inc world-width / grid-size-x9 w, a0 J3 b7 o1 y! @
  set grid-y-inc world-height / grid-size-y$ k% ?5 M9 R" l* ]+ T* S! s

7 @& a3 ?! a3 k5 A. O/ H  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 R, F8 V4 S2 Y" U' v  set acceleration 0.0999 U: Y9 S* w' l
end
2 u8 [! v; `5 j2 x  \8 t
/ F- W# w) w8 Y$ P; {;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
! e  r! l# }; U, o$ X& l;; and initialize the traffic lights to one setting
" D! G+ g0 Z# G" Qto setup-patches
( K; Q2 [: k: j- `9 J' x  ;; initialize the patch-owned variables and color the patches to a base-color
/ ]; n: l0 L8 d3 [  ask patches
/ J4 H  d# i3 N  [
& z) f  e. {0 l* n: N' ]    set intersection? false
# y, H# ^% d# F4 Y6 ?, A) V) B3 F/ S    set auto? false
, ]; P2 c' |! B# W# f    set green-light-up? true( Y8 v+ o1 w0 k. t
    set my-row -1
7 s' r4 m6 X& t) @; L" X    set my-column -1
, T" C  k! A( |! X# A    set my-phase -1
: N; J# g' r) S( j% w8 M    set pcolor brown + 3
/ o; N- D- l  w" D' @: w. u/ }6 [  ]3 r2 z; y# n, q9 R, ?, z6 v7 f

8 d# ?9 {3 O# `- X  ;; initialize the global variables that hold patch agentsets
" U$ F! M9 `; `; i* ^/ h  set roads patches with
' o3 M, B0 d2 H7 Q* _: D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 a. I  u) t& k0 r
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( d% j3 l7 L4 b  set intersections roads with
+ R! }% l' n$ O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
/ G/ @/ [/ L8 Z6 T- x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 ~! m% z) C0 {* ^5 ~2 ~; x5 M3 [( E) ]# W( K& b
  ask roads [ set pcolor white ], n) y: E' F7 v
    setup-intersections
2 j: L# T7 P$ X  V) H5 u6 jend- J1 j; q  q! o* V8 ?1 L
其中定义道路的句子,如下所示,是什么意思啊?
, K2 @4 `& C" l) |' k2 d set roads patches with. l2 Z. p" C9 U% ?6 {
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* n6 B  ]  S- |; q$ B6 J# @5 N    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 a+ e0 _: V1 @( 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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