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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。1 m- K/ U2 }+ U0 |& {
netlogo自带的social science--traffic grid这一例子当中,
; |2 T; l2 E+ A7 a  F# o) Lglobals
  D+ j: z) J& a+ Y[
+ Z: k2 i: O) }$ A  grid-x-inc               ;; the amount of patches in between two roads in the x direction+ x- j% n, O- v$ |1 ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction# u1 |# d& N& I, c( S# w
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& ~. I# V" _  `5 {( [
                           ;; it is to accelerate or decelerate
! v2 R5 J7 m) n- o  phase                    ;; keeps track of the phase
  K1 |0 V5 \$ a  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 T. e. c, F- j$ m; G# p  current-light            ;; the currently selected light
' D' ^3 u3 o. J5 z" f
( W% [6 [4 Z8 S# R/ z  ;; patch agentsets2 i, X) c5 s/ W+ B( k; g
  intersections ;; agentset containing the patches that are intersections
5 d5 C$ r' p/ a  roads         ;; agentset containing the patches that are roads3 u* M6 G. F. F& F1 c) y3 O3 \/ f  |
]
( W$ w( v, Y, B7 K& }/ r) x# r
! J& u' v# r; G' Rturtles-own
& \3 I$ W) B# |; c* f3 x  k[6 O; o4 [" T3 P
  speed     ;; the speed of the turtle6 }* L3 d* I( P+ p9 v9 e+ K& P
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 q$ J* w8 i/ R7 M  wait-time ;; the amount of time since the last time a turtle has moved
/ W" H! Z3 g  i6 y( m8 p7 g" Y+ i]
+ {% v. n9 k, z9 y$ v, v- H
! X# {5 v6 K* X" Q# [; A/ g0 _patches-own
4 M1 a1 E/ {) g; z& L- [2 i[
2 T3 m, V- e$ j7 e* H  intersection?   ;; true if the patch is at the intersection of two roads
) K: T/ J: G6 n  o# V3 `# S: `  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 O$ i1 C+ S2 [  i- [0 X3 i                  ;; false for a non-intersection patches.
  o) Y; B4 x. j0 G& t  K  my-row          ;; the row of the intersection counting from the upper left corner of the
! K- P/ ?" g8 Z# S/ ?7 `1 }: ^                  ;; world.  -1 for non-intersection patches.' e7 G' W/ y: k, j
  my-column       ;; the column of the intersection counting from the upper left corner of the& w7 S, E3 u( c8 I  B  M& k
                  ;; world.  -1 for non-intersection patches.
8 ?! {: V+ D8 B( ^8 r  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! R2 P: L7 w6 M: z- Y! u9 _
  auto?           ;; whether or not this intersection will switch automatically.2 @, ]2 }5 V# O4 s
                  ;; false for non-intersection patches.
; }* j* R" g; q7 U; @]2 N6 w- u) h% H7 n( \% X

3 @; q# L& ]6 q. x& S, v" J7 y
$ x! _$ n5 Y" g$ C7 N5 ~- o;;;;;;;;;;;;;;;;;;;;;;. e6 _  T) p3 L( x) Q
;; Setup Procedures ;;
1 \# c! H4 y+ W: O;;;;;;;;;;;;;;;;;;;;;;
- _# N+ K  g- E% {
/ }1 |' _& z5 \;; Initialize the display by giving the global and patch variables initial values.
# r; d3 t! n& b& E% f6 D1 b# p;; Create num-cars of turtles if there are enough road patches for one turtle to8 a0 J4 r6 T7 U
;; be created per road patch. Set up the plots.
2 E  g. Z4 P: C$ P. o1 f8 c* c2 T2 G$ fto setup
$ W/ ?: C: z; a* @5 x- h; K  ca1 j" O( z$ p  |5 v( y
  setup-globals+ H. u/ X3 d+ D* Z' r9 M! ~% O+ O, R

& i( p9 ]; Z  r2 L9 u# M# o  ;; First we ask the patches to draw themselves and set up a few variables
/ g8 f. B) E- m  J- n* k  setup-patches
& T! j6 s% f* I: M. l  make-current one-of intersections1 p* C* p* p) ]" T, ~) w8 L9 t
  label-current
& R' O* Y: C2 H( _  N% x: o, `/ f  Y+ z/ R
  set-default-shape turtles "car"* N0 l1 Y  p8 k, c3 }

4 o6 @( w) m1 g6 b( Z' v  if (num-cars > count roads)
3 ]4 L& ?9 H. j) ?& N# q  [
) b/ j, [) z! @% ]- C) t1 e3 a    user-message (word "There are too many cars for the amount of "
. C# o5 R( }4 `( ^                       "road.  Either increase the amount of roads "
: E1 m( a2 n& l7 i4 v0 a                       "by increasing the GRID-SIZE-X or "
" g% a) N; V  |0 g4 f7 ]. _0 t                       "GRID-SIZE-Y sliders, or decrease the "
! l3 c1 y' V: E/ [9 [- i  d& d9 W                       "number of cars by lowering the NUMBER slider.\n"1 l2 K7 N" E7 D3 Y; q9 E
                       "The setup has stopped.")
/ n8 D8 }7 w! N4 u8 n    stop
. {' b; V7 q* k" e6 O  ]# L; {% r5 c6 v" }8 F5 @
6 j- \$ l1 B$ c
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color6 H2 M6 v- q% y4 B* c
  crt num-cars# L0 @0 Y1 M' W8 z
  [$ X6 q* U" p  n7 P( _/ }+ H
    setup-cars. \7 v, k/ k  A9 b/ \3 {& t
    set-car-color  S! U  Z: w& J& ^3 ^7 O7 j8 b' F
    record-data
' ~; h) u1 z/ t  _  ]
% }' Z6 i' Q2 h, e
) i8 e5 c/ T+ Z- t  ;; give the turtles an initial speed
% k+ U2 y( Y# Z* J9 m) n  ask turtles [ set-car-speed ]
. ]- ?. o& `; W% R8 y( [. B& s8 J! @2 a5 k. b0 R
  reset-ticks1 {( @/ V& ?: ?. W7 |
end' ]6 `+ [' I9 q

: D% X7 l$ x( H: R;; Initialize the global variables to appropriate values
9 Q% _% b4 M1 e! ^4 l* {5 uto setup-globals
- v0 ?* x8 C' t- P6 e  set current-light nobody ;; just for now, since there are no lights yet1 q5 y* R% ?. k7 c7 }
  set phase 03 z& ^* Y7 X, m
  set num-cars-stopped 0. y6 n; q- t" z4 }: ?4 m; E
  set grid-x-inc world-width / grid-size-x
) U! j; T* k+ Z1 O* f  set grid-y-inc world-height / grid-size-y5 V  N: Q- Y. o
8 M+ G& f1 u# q  s3 E  h! q' Z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
4 A: `- O5 ~2 `+ x0 L0 M" o  set acceleration 0.0994 q+ \% R! v% R+ ~, p
end
( I5 e1 W: R' x
, z, W7 r1 a& q: Z! [0 L5 Y;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
& p) h& }4 n5 ^$ a. g;; and initialize the traffic lights to one setting
; l+ K: t, D5 dto setup-patches: M6 S4 w& T/ m3 Q7 T$ @# U
  ;; initialize the patch-owned variables and color the patches to a base-color
8 ?% b1 b, v& ^- o  ask patches# R0 `# z  J9 v6 A2 x8 M5 w
  [
  p& R4 Q$ ^( f0 A3 R    set intersection? false2 u0 ~9 R' G! F( Q0 j
    set auto? false5 G( }1 P" [9 n4 T' C
    set green-light-up? true
7 l# \' g; s) c" c6 p    set my-row -1  B* C# M+ _3 x% \
    set my-column -1
( R- B# ^: }# W* `9 k) ~; Q* ^0 l    set my-phase -1; F& {- ~; w( J) b; l
    set pcolor brown + 3- u. i9 @8 p7 n4 i% Y* U( v9 D
  ]$ {+ J" z' L/ Z% K! ^
( _9 f# L$ j1 I7 u# }
  ;; initialize the global variables that hold patch agentsets, Q+ R/ l6 p2 y2 {0 U0 q! G# l! r
  set roads patches with. P! V/ ]& W$ V7 Y1 j0 i7 Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
6 b2 V' [' [3 G# m3 ?; v    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 \  g, `4 \3 x3 \& O
  set intersections roads with
% {# m# |5 l) j    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* g) b, k7 B' J' l& p    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& H) S% B3 Z- e! B
0 Y4 I# U( O% f+ J  ask roads [ set pcolor white ]
- q6 q* z7 ~# `  \. K# q' y    setup-intersections
( H7 E; h/ v/ j% E+ \' r8 k* Iend
$ f3 h$ z$ P) ?6 b5 F- h! c5 f- f! T9 J其中定义道路的句子,如下所示,是什么意思啊?
3 m7 w7 Z/ r% q0 h8 K/ h1 S set roads patches with  u# Q, h% o) N
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 d2 ~7 D& m5 Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]# a- M0 C- B# O' G
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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