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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。
. s) A. S' H/ R  Vnetlogo自带的social science--traffic grid这一例子当中,
4 E; v+ I6 [' G$ o8 h) eglobals7 }" v' A2 d7 J6 ~2 w5 V
[
) c# b) A- E- b  U9 {3 I2 E  grid-x-inc               ;; the amount of patches in between two roads in the x direction
  g! n! u- x1 ^" F  k% X  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) [/ H& G& _, x# k" q4 A  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 i0 N7 ?% o5 ?5 f$ s! t, }6 n' e: V                           ;; it is to accelerate or decelerate1 q) E) ^  M( E
  phase                    ;; keeps track of the phase
, j) |# N- J( j0 a& ~+ n4 X) O$ [  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure  {4 M* Y# s) @7 Q9 [
  current-light            ;; the currently selected light; l, [  {6 N: t. t. Q# z

5 d5 v4 c3 }6 p4 s0 _9 X  ;; patch agentsets
/ T3 A8 j$ ?$ {% X  intersections ;; agentset containing the patches that are intersections
" c  ]: ~7 D6 s3 `. \  roads         ;; agentset containing the patches that are roads2 O: t: v, e) y4 q7 @* t& Q3 q
]
" x0 o  y& D, a. V2 H# ~7 p$ _) V5 f) e" t7 T/ C
turtles-own! F$ J# [, Y) e8 P- g
[
: o7 s" M  K! d  y- D: Z  speed     ;; the speed of the turtle) F0 A0 @/ {' Y0 \4 s/ b
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
: {7 }7 s! Z+ k5 B" @7 U& Z  wait-time ;; the amount of time since the last time a turtle has moved
' F) A& o4 [: y6 |+ H6 Z+ o1 a1 f], C0 N! ]* Z4 x& z* ?+ A
) L# \8 d; i/ q& l8 N% q  d
patches-own1 o+ O  l* C5 g! E# n9 V, y
[
: h2 k8 _0 y8 K  p9 J  intersection?   ;; true if the patch is at the intersection of two roads
# z8 ]; L3 n: n5 [+ A  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 {7 N* U/ A4 l                  ;; false for a non-intersection patches.$ D* T7 e6 W2 W) S7 s$ f
  my-row          ;; the row of the intersection counting from the upper left corner of the8 s0 ]& _9 E- V4 T- z/ V' T
                  ;; world.  -1 for non-intersection patches.  T/ [: F% P2 j9 U) s: n
  my-column       ;; the column of the intersection counting from the upper left corner of the
4 n. A0 E3 N, C2 B$ M) U" s' Q                  ;; world.  -1 for non-intersection patches.' r, Z: b2 `( m& z
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& `$ K% u" a1 C  auto?           ;; whether or not this intersection will switch automatically.
! L( t, e# I7 b2 C9 f) Z                  ;; false for non-intersection patches.
, m/ [; z7 k9 U' j& o]
( ^$ \; N  L: y5 [9 k2 {  Q8 ~6 k7 t# a" f8 Q

6 \" t" U6 \: u! D;;;;;;;;;;;;;;;;;;;;;;/ `# ~& _4 s3 N" e* t
;; Setup Procedures ;;
8 A3 q( H0 I! Z- P  r  i3 \( x' n;;;;;;;;;;;;;;;;;;;;;;; J! O9 o/ @3 S3 I

( t1 v: W/ |, k' H;; Initialize the display by giving the global and patch variables initial values.
9 [4 ]( L8 ?" F0 e' b' i;; Create num-cars of turtles if there are enough road patches for one turtle to4 `. n# N! O  U
;; be created per road patch. Set up the plots.
# ]6 B5 s3 r, K* |9 U$ [to setup) m5 @( E* q" ^4 ?8 d
  ca
( d( L7 a+ W4 F) F1 K5 Q- Z  setup-globals
+ @/ V1 X2 R4 ^! f* g% x# `# B" O6 ?/ I3 ?
  ;; First we ask the patches to draw themselves and set up a few variables- |& I; U0 X" j) g4 S- N0 g6 y
  setup-patches0 k: k9 A- N5 o/ i  P* n; E
  make-current one-of intersections# k7 {. I5 I) X6 P, Q$ o( q5 a# }
  label-current
8 t) J, s. f. W) w! R, ]$ [& ?
7 p: E! I, _7 _  set-default-shape turtles "car"9 o* V' O4 _& y

0 L; \+ [7 I6 e2 e  if (num-cars > count roads)0 [/ \8 M. h: m! B) X
  [
" n+ X# `+ D/ A/ C8 @7 I    user-message (word "There are too many cars for the amount of "1 [) y  Y2 p8 d& d# }8 m5 ?5 s
                       "road.  Either increase the amount of roads "
! `9 u7 ^  N8 `6 ^1 ?/ `                       "by increasing the GRID-SIZE-X or "
4 {4 y' _; S0 C( b                       "GRID-SIZE-Y sliders, or decrease the "
: P# }1 O( c+ x& \                       "number of cars by lowering the NUMBER slider.\n"
' |7 k6 L: i. Q1 w; H" @+ K/ D& l+ n                       "The setup has stopped.")
9 u2 q8 u( B. d; G    stop* j6 `2 m% g! t2 K7 A) \
  ]
- H9 Y8 R8 P1 H# Q$ c5 j6 r" m
  U  h5 O0 q7 \. H# N" p$ L  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& Y( M+ X3 w$ |, g8 X' q
  crt num-cars
# ?$ X5 P1 Q% ?. a1 u" w( e4 c  [
; Q  L- L4 |8 x3 Z5 r    setup-cars0 l2 ~1 ?% K; w- P4 `
    set-car-color
  J* Y6 s# H5 g& p% j    record-data$ [! d# N: Y3 l  }" a
  ]
0 C# ]' g6 r2 b  o. O$ Q- ^( l
$ U& N* v6 z! \* ^2 i1 t. Z  ;; give the turtles an initial speed1 }. ^+ O; G: m7 t  M/ ?
  ask turtles [ set-car-speed ]+ d. O6 U2 y7 [) V
: q! r6 i2 C% g# g) o" q
  reset-ticks
7 P" g7 ~* |7 V& ?" [end: q) M8 |9 J0 f$ R% \
, q; D2 C9 q# ?+ A5 `7 C
;; Initialize the global variables to appropriate values2 M- ?( k2 E, b! y8 W
to setup-globals% m7 D7 P9 j2 _, T/ L: t+ E
  set current-light nobody ;; just for now, since there are no lights yet
! H" |) M) A+ L6 k  set phase 0
2 J. ]( H/ Q1 |6 B: K3 ^; p( S  set num-cars-stopped 0
6 d& l0 q7 P$ R  set grid-x-inc world-width / grid-size-x
8 m5 P1 G2 A: }8 V  set grid-y-inc world-height / grid-size-y
7 ~% N* X$ B6 O2 O: c; L7 O
. }3 x4 p5 B2 {' o9 w& m  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% U* F' F5 e$ w* w" z  set acceleration 0.099( J* y# i( x. E0 `! j' X# A
end
9 m3 a5 v: A3 t. O5 y
/ }3 L! o  _' W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 B3 j2 \! B5 q% M1 A5 m3 y;; and initialize the traffic lights to one setting0 S& W% I  f3 @  R5 {! F
to setup-patches
2 p* J  a3 `- q% j, z9 _  ;; initialize the patch-owned variables and color the patches to a base-color6 |, k# X& l* `. w% a: }
  ask patches
& p8 x" N0 X* K: I  [
- Z" {- w) h  u5 I    set intersection? false& R( I  {# i) Y
    set auto? false& [. o$ f& s- O5 ]& W7 m
    set green-light-up? true
# M* ^6 Y5 n+ O' f" {7 i' f% D0 D    set my-row -1
) m) h0 X9 v" i% h. y3 |6 |    set my-column -15 n1 ?9 R, u  x
    set my-phase -1
9 V3 C$ ^% D7 q3 Z1 p; t    set pcolor brown + 3
- h5 }' D4 f0 t' h3 A& b3 d, u  ]
$ \! i. B; x- ^# a1 p8 l
1 w% g/ v( K3 B4 I( T- |1 _. [  ;; initialize the global variables that hold patch agentsets
0 Y4 {7 Q& u4 u2 _+ y3 g) N. S4 {; a$ K  set roads patches with
. b: n( }8 ?! l: q. l7 N: p9 w/ [2 O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: m$ z9 V' Y7 |
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ ~. y. _" I- ?( s! `  r6 j8 v2 }
  set intersections roads with
" N0 n, A8 }( c- A, W. U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* \6 x  g2 H6 g. V    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  ?; n) w9 p. S. `9 [

: s6 ]5 p, t. _2 F3 d2 G6 h  ask roads [ set pcolor white ]+ f/ Q* q/ K% ^2 w$ G! M0 z
    setup-intersections8 r0 k3 A9 s  p  H
end/ l5 q2 H, m  s4 L$ C0 L) t! _$ q
其中定义道路的句子,如下所示,是什么意思啊?
  J$ Q+ D+ q4 ]& M& o# A set roads patches with. O6 H+ q6 }# `- D! R
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, U9 i4 I+ E! ~% w5 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 a& I& D% U+ i. |0 k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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