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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。
- c, u! E& r$ g. m, gnetlogo自带的social science--traffic grid这一例子当中,5 \/ @1 g. g) r# d! \) a
globals# p+ ~1 v8 k' s" r; S
[5 f4 v5 K% _: E3 R0 U# P1 w' S
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 l  z# c# O/ j
  grid-y-inc               ;; the amount of patches in between two roads in the y direction0 W& B' K6 W+ k4 q# F
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ ~6 F% J# G" ]0 L" y$ d+ z
                           ;; it is to accelerate or decelerate  n1 c8 I$ \; ?: z4 e
  phase                    ;; keeps track of the phase
% p' V" s- @6 r( n$ Y( G4 u  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: D6 O: f/ y! h' e8 n5 T" U! H  current-light            ;; the currently selected light3 H( C$ n* r4 r, r+ i% t3 |

' A6 L; Z( v1 l, W1 ^  ;; patch agentsets
+ B1 v* S( ~  _, ~& S/ b6 Q  intersections ;; agentset containing the patches that are intersections- b, |- h9 [8 w3 U: J
  roads         ;; agentset containing the patches that are roads8 {1 U( C1 s$ s9 N
]1 p& x$ m2 {; N2 u3 i4 U
' F( I% X! |: u, R) O" j6 W
turtles-own
9 r" K& C1 {% j+ q$ W[
' z0 Z( {6 I" M! E( o5 i- E  speed     ;; the speed of the turtle7 E4 b/ {" Z9 `5 T
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, [. c+ G2 V8 u6 ?# Y! j
  wait-time ;; the amount of time since the last time a turtle has moved) d6 }# Z5 g7 \( x6 B( B
]2 Z/ `5 V6 D* S8 r5 l

! |( O  s2 S2 {: dpatches-own
, ?/ O1 n/ s* f- z2 Q1 A  }[% f- i" S% m, w1 |, `" G
  intersection?   ;; true if the patch is at the intersection of two roads
  e  U% F  }4 @# d0 e+ }  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. S& ?3 z) J( [" G                  ;; false for a non-intersection patches.
& I( |$ R6 U" s  U( N  my-row          ;; the row of the intersection counting from the upper left corner of the
5 x+ N. g- z& Z6 T" C0 t. v: K                  ;; world.  -1 for non-intersection patches.
# L1 U2 x1 K; ^3 d  my-column       ;; the column of the intersection counting from the upper left corner of the
7 W+ T& _. D8 k9 l5 O# f* T                  ;; world.  -1 for non-intersection patches.
7 `5 h$ ~% q4 ~  F  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
  w) r4 D. p% \7 _6 K' Q/ H  auto?           ;; whether or not this intersection will switch automatically.' `7 _) q8 A; c
                  ;; false for non-intersection patches.
2 `' \7 L; c3 L2 A- X5 @]
/ e/ x$ k; }" y6 o0 e. S: R: x# U# }  x

! X* b' c6 l$ ^7 ~! _- ]5 C;;;;;;;;;;;;;;;;;;;;;;
% P& S  F* K, E% E# z: S0 ?;; Setup Procedures ;;' j2 U  |! V' c6 ?6 v
;;;;;;;;;;;;;;;;;;;;;;
+ E0 `0 }6 M# q5 K+ K" z) b5 \1 P7 C5 j8 x; Y
;; Initialize the display by giving the global and patch variables initial values.
8 [& ^3 k) O" `;; Create num-cars of turtles if there are enough road patches for one turtle to- E8 w" u9 I( @8 I1 M- K
;; be created per road patch. Set up the plots.
4 W2 u) q* e9 j  H  F* Xto setup
" x% \/ q; q' b8 q  X: h  ca
4 d) y3 G5 l: ^; U$ m) `  setup-globals  |2 Z) @9 g$ P- B8 M+ ?( Z
, `7 }. _0 R6 d6 E
  ;; First we ask the patches to draw themselves and set up a few variables  _" O( W' b: v6 ]( i9 d! l
  setup-patches" X2 q% h% b* x6 Z8 R. y
  make-current one-of intersections
/ N2 N# G. R# d0 W  label-current& l$ F; e  e3 {% f3 i6 t
/ Q7 l: n+ U. c2 n% l, v
  set-default-shape turtles "car"
2 X, F2 J7 s/ L' k5 v. u' n  ]3 K% E9 i7 C
  if (num-cars > count roads)4 L: `8 W% @9 z; G' E+ T9 _
  [  O7 `$ U5 v3 z/ V8 x
    user-message (word "There are too many cars for the amount of "/ k% A+ @5 i1 _" S5 S/ d7 ?
                       "road.  Either increase the amount of roads "
4 m* A: i* B3 ^" u, Z, T# a8 w7 Z                       "by increasing the GRID-SIZE-X or "
( l- \' H" E# f                       "GRID-SIZE-Y sliders, or decrease the "
( O" B2 z* ?. u  J3 z9 J                       "number of cars by lowering the NUMBER slider.\n"
/ j) T5 f' D. d# g2 ]. n                       "The setup has stopped.")
/ \  r' I. k. m3 ^+ g    stop
5 W6 M& G' o- I! R* ?3 N  ]% J1 _# @& o- \
9 B+ |, @% K. t% g
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
: O& u( ~2 l/ [3 }$ ~2 `. N  crt num-cars
# e; ?) Z; x6 v6 U. }; m  [! e6 N. u: J2 r$ O
    setup-cars
, i# j& P4 w6 M0 V' ~6 r# @4 E( E0 y    set-car-color# j+ ^0 A/ }* i5 K" N$ w7 I
    record-data
$ U- {9 f* N6 K  ]
5 e- M8 Q3 V. m- q0 D* U1 i6 T$ `4 o$ N* V! v
  ;; give the turtles an initial speed
2 G  H2 {! c% n; T  ask turtles [ set-car-speed ]
6 `- w) d" P) S. f/ \: |' [/ n7 v% ]! L, y& Y' s
  reset-ticks
9 Y0 M) K6 C$ Rend
1 {, W8 U2 Q' b' Z+ t( B1 r; y+ f7 m/ J# U/ m
;; Initialize the global variables to appropriate values
9 ], ]/ Q( o& Z) V) H2 Eto setup-globals
* `; Q2 l6 N3 c* M: `3 S) v  set current-light nobody ;; just for now, since there are no lights yet) E5 F4 k8 ]* i$ H+ \
  set phase 0- s' d. M3 Q! ]0 D1 T' O
  set num-cars-stopped 0
$ j1 L0 j- \' w- e  K  set grid-x-inc world-width / grid-size-x
& V3 ^" S  A" T$ ?6 N  set grid-y-inc world-height / grid-size-y% O% c$ s& t- p: v" J" A4 I9 R

5 i0 s9 U' k1 e$ Z$ `& N3 ], B  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& E( @+ g, ?. E; E6 m- b8 v( ^  set acceleration 0.0997 d- c$ p) W1 ^& Q
end
2 V" F7 |. E1 c9 T4 w
5 f  _$ I. o2 ]' ^1 W;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  r5 \& @, s- L2 ?( K;; and initialize the traffic lights to one setting8 \8 m) c5 K, g* y+ A# g' k7 C
to setup-patches
  t/ _) ]7 N- n  `- x' `  ;; initialize the patch-owned variables and color the patches to a base-color+ _$ O* h2 ?/ I4 w
  ask patches( y. P$ t+ t' D* T& V
  [
2 q1 o9 {; c9 N- K    set intersection? false
0 f) y1 j4 v1 D5 X5 i+ Y    set auto? false
9 Z: u2 L' x) r5 O' m; W/ g    set green-light-up? true
* d% z, n; A6 j' `' Y) w* ~# W2 L& s    set my-row -1
7 [4 B5 ^0 Y0 Y3 B+ W- H. `% [! R    set my-column -1, T8 E6 ]) F7 L' w
    set my-phase -1; l) H6 N$ \( ^6 C' a; m/ l
    set pcolor brown + 33 H- \. T! Z3 b6 E
  ]
* O6 H1 I. u, E; i& D4 [
0 A( s9 W! e, U6 @& @  ;; initialize the global variables that hold patch agentsets
( \1 {1 J8 c" }4 M: S7 A9 S4 t  set roads patches with  n5 a' A3 H2 \* ^' U- E, R0 e
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 m, K2 Z* n, j" u8 Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 q. D0 K4 d/ z2 J3 l  set intersections roads with5 O6 `% ~5 _1 i; v) a0 ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 a- \- s) O* Y/ f& i6 v
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  {+ \: d! `6 \8 |( z! R# @: m( ~; Y3 G5 N
  ask roads [ set pcolor white ]
- O' O6 b: z1 t4 c* {% {+ \8 T$ t0 |    setup-intersections
+ @6 V! d8 x/ e' j( Iend
7 z" \. E6 Q; X8 a8 c其中定义道路的句子,如下所示,是什么意思啊?
" T' F3 }( a8 ]# k  H  P$ G set roads patches with3 l6 K. H. }% c6 s4 }5 d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
- T) }8 L- p+ W- o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% V4 G: t% z0 C" `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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