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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。
2 M4 e9 X4 x! F% T3 z- i; P# cnetlogo自带的social science--traffic grid这一例子当中,
9 n% ]0 i( y; rglobals
7 ^" L7 p3 M$ A# J7 W% U4 p6 o[" E' e( p! R! f7 d4 u7 V- i7 i
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
7 n# J6 E' e) \  grid-y-inc               ;; the amount of patches in between two roads in the y direction
$ \+ U( `, B& C( k* e0 n1 |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 K( g) r- f1 M2 f9 `- E
                           ;; it is to accelerate or decelerate
5 W6 I4 R4 H  Z# i- U- v! c  phase                    ;; keeps track of the phase9 k" X! r9 t+ p7 Y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 y: q7 M. d' i# \& K  current-light            ;; the currently selected light! ^5 N% l3 C, t" b* C; I" v; E" y
! Q5 H5 p- |2 P- H2 s2 S9 m$ T
  ;; patch agentsets
0 I- k0 p0 Q  t. p& }2 o% O# |  intersections ;; agentset containing the patches that are intersections
/ j% q+ `1 u& ~  roads         ;; agentset containing the patches that are roads
' L8 v0 [% z7 m; R]
: \: F" V6 V2 j& b
  X3 J: ~& y$ O2 W; wturtles-own% s( c# O, [/ y5 Z5 C) a
[
" c3 ^( u1 r3 @( Y3 V2 o1 a  speed     ;; the speed of the turtle0 }7 v. ]7 W" ^/ D$ x3 d9 [) m
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# e$ M$ D. a# L! v  D  Y6 v  wait-time ;; the amount of time since the last time a turtle has moved
) \( t( |+ j+ k2 h' `]3 K2 O$ i0 v0 b: B8 u6 i
* ]# p( @# ~& {+ {$ }. a
patches-own3 G* h7 o- y- z: W. M+ O5 k
[- K0 k8 G" t' P: y& X  ]$ g
  intersection?   ;; true if the patch is at the intersection of two roads2 y! V/ x: K* u. i; P- i
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 K2 @' }4 N! A3 v5 c+ D
                  ;; false for a non-intersection patches.# o) e' h% D: O$ b: Z: Q! s* i+ S
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 g& D9 @' [  v& T2 \                  ;; world.  -1 for non-intersection patches.; y3 o" D( A3 F, y
  my-column       ;; the column of the intersection counting from the upper left corner of the
+ r4 M" F7 `4 K6 i                  ;; world.  -1 for non-intersection patches.
; a% p% {6 g! H8 D7 W! H; ~  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ c& }/ P% S6 F) h- v0 ]2 J
  auto?           ;; whether or not this intersection will switch automatically.
, j& `) ^. E0 `& s% P" P6 u                  ;; false for non-intersection patches.
, W, c5 E7 S. @- y]
$ A4 r/ \& r2 ]4 C+ R
7 d- V. V/ K  j' Q: R6 g4 [
: [) I: R4 {6 R;;;;;;;;;;;;;;;;;;;;;;( y9 H) r8 `3 m! a5 B
;; Setup Procedures ;;" F% T3 k1 O4 F7 V
;;;;;;;;;;;;;;;;;;;;;;, E/ q) y2 J4 R( E/ f
' d" w' x- u5 ?( \
;; Initialize the display by giving the global and patch variables initial values.
$ }( ?- E+ g; E5 v2 M3 \;; Create num-cars of turtles if there are enough road patches for one turtle to
6 @) V+ U* u  {; ^+ W1 N( {& A;; be created per road patch. Set up the plots.
# m7 D  s" q. J( V0 w3 zto setup
; B8 x1 |9 b1 E, Y" @  ca
( }3 L" s' D0 s6 N! F/ A3 [7 J  K6 _% f  setup-globals5 I, M7 B% Z7 s4 a# u
0 P5 B& q' u' s) h7 ~
  ;; First we ask the patches to draw themselves and set up a few variables
* W/ I: S+ S. G  setup-patches/ @4 c; W) O" e1 a4 E6 a5 g
  make-current one-of intersections
4 L9 ?* I- i9 v6 F- O: B4 n) B  label-current
+ A2 f$ P. S+ ~0 C  b  \4 s7 T8 a( R" u% m6 a9 T
  set-default-shape turtles "car", s; a( w' ^! K# G. i
7 {/ y  Q: \- u& e
  if (num-cars > count roads)* O; d( F3 p, ]" b1 j! ^& k0 l4 T! |
  [
& d) N% o/ a8 G6 i    user-message (word "There are too many cars for the amount of "
& b( v: F" E2 R9 h) F6 x- ~, E                       "road.  Either increase the amount of roads "
2 |, N: r9 y5 X/ p                       "by increasing the GRID-SIZE-X or "9 z6 S- ~: f, W0 W* R9 M
                       "GRID-SIZE-Y sliders, or decrease the "9 \2 W1 G: }% y
                       "number of cars by lowering the NUMBER slider.\n"
- v5 l/ m+ P( k8 R5 J                       "The setup has stopped.")
7 W" Q6 ]( t# s; t    stop+ p# l" `, \( f! y' x) z
  ]
1 m: i' r1 Z1 d; z5 A- k* K$ K+ L7 z  ?6 y6 ~2 X5 T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 J4 m' g  x* Y( _: h
  crt num-cars% r* C0 z9 q, b
  [
1 h* x: ~7 e* t  S* U; G3 `# P    setup-cars
1 V5 l, H, l; v1 c; F7 v, q    set-car-color
+ E# N% P( Y0 r5 K9 K* u+ l    record-data; m# c9 r0 Y! _
  ]3 g8 w6 C# @- M' @5 o: l

! B' K  s& _+ f1 b  ;; give the turtles an initial speed
4 e# ^5 _& j8 v: m* ?  ask turtles [ set-car-speed ]
; Y& b9 ^: ^5 [& D0 }+ i0 N( g; ]; O+ J  y) Y: `5 K
  reset-ticks
8 o/ S/ i, J! W2 T# rend* {$ ^' I0 ^7 F$ Y& C: _

8 w2 u( b$ G! o5 [# ];; Initialize the global variables to appropriate values
/ A* t. S: k, Cto setup-globals
" x6 n) V- y4 p* h0 Q; H  set current-light nobody ;; just for now, since there are no lights yet/ Z. D- @) d) j% F9 O- g2 d- j
  set phase 0
# f& k- J- n9 s3 e  set num-cars-stopped 04 T, W0 j: X3 e+ ~, E" F
  set grid-x-inc world-width / grid-size-x9 |: p3 x* M$ G$ P" w+ X8 ~
  set grid-y-inc world-height / grid-size-y' ?6 m0 J  R9 d( c7 ]1 ^) P

% \9 W' ~- v2 b4 t5 \2 Z4 J  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
' Q* R8 d6 \/ P8 T1 g8 w  g  set acceleration 0.0990 j. Y# c1 o1 I; L4 \; {9 j
end
# u& @, y; `' @& o7 W/ e* l& X+ B  v  e. h& c4 A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
' A' r! Q& M4 p1 ]# t;; and initialize the traffic lights to one setting
0 ?3 x' b) k. \4 |# }# B. g4 p0 eto setup-patches
' d! D- l# T' j/ @7 n2 X  ;; initialize the patch-owned variables and color the patches to a base-color9 E. E9 z) ?2 ]. c
  ask patches: F: J% y" @9 w$ R
  [
( v% W! ^& x0 ]$ R2 f/ T    set intersection? false
7 Z! Z" n9 N+ y. @- \0 e; m; k    set auto? false# I% n9 n5 S% [0 I7 x& J
    set green-light-up? true
" n& ~+ m% t! }* t9 [+ \: P    set my-row -11 D5 V- p4 C8 Q! ~& A3 k' r5 W
    set my-column -1
2 y+ w* w2 l& \. {    set my-phase -1
) D$ C6 q0 i- _) l6 }    set pcolor brown + 3
. i% p, T: \. p! P' ~& ^9 y  ], V2 d) w  v) D6 \
, H" \& l5 c" ~$ i9 M6 t
  ;; initialize the global variables that hold patch agentsets
" ?+ `! m5 S  y$ ]7 e  H" V" |. K  set roads patches with
$ F) C, y5 Q, I3 W6 b3 [% t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% d0 _) n# w; m- k/ d& [
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]& a# u7 q/ U6 G
  set intersections roads with
9 F8 A. b6 g8 E6 l* h5 Y3 ^4 P6 H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. c4 c1 y5 D! Z0 H5 G
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 ^) L4 |4 c* ?) H# S8 U/ A& [' h  U; G- Y; o8 d) ~
  ask roads [ set pcolor white ]
* M5 _7 I% I' g$ ]    setup-intersections; e, j8 w7 P( N$ s$ l0 P
end
6 `9 q5 ]) b3 f# P( y' z其中定义道路的句子,如下所示,是什么意思啊?
" d& @) K1 O- Y6 Q set roads patches with. g3 Z: K& |5 h% d$ t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 n+ J7 ~% [6 |0 [& b' M    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# R/ j4 {5 [0 a1 n# f' 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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