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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。& h! f6 a6 x) o2 p$ L
netlogo自带的social science--traffic grid这一例子当中,
  N2 N( ~$ F, F' o% n8 A  iglobals" }; u4 V0 `  Q, b) Q" K2 P* @2 p
[, [( \. j' m; V
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# |9 \# P" m2 R  grid-y-inc               ;; the amount of patches in between two roads in the y direction
! {/ I, d3 Y9 R# h: P, `) O& A! W8 _  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: g6 X% z0 c4 c1 P
                           ;; it is to accelerate or decelerate" p' r) h* f5 x' f
  phase                    ;; keeps track of the phase
  M& d' l4 r! S* }  ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
1 \8 a: Y: j# I$ A; |3 ]  current-light            ;; the currently selected light
, w. J1 h) C$ f3 x' k- N" P7 H
, F9 X5 I$ `( p! B, d$ u8 i  ;; patch agentsets
% g  z% G4 G& h/ k% z$ [  H  intersections ;; agentset containing the patches that are intersections" [" @, n2 e2 m4 i' F, ~5 \
  roads         ;; agentset containing the patches that are roads
9 D% K1 V. }) z) u]7 n, w) m) a- i2 `
8 h8 X. K# [2 I) c1 Z/ g
turtles-own
2 z5 f8 f* e. _! s[
- v& T$ D% T4 g2 w3 @  speed     ;; the speed of the turtle
1 u0 [4 j* [3 _" u$ [3 b' t( t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right3 N: {* l% G% c8 u2 a
  wait-time ;; the amount of time since the last time a turtle has moved7 N* K9 H1 V, Q# K! v
]* v6 {* N! R9 b

9 ?4 n9 x5 @: s% Q2 p- H; _patches-own
! l  O0 b* ^5 V5 \2 \: t' G[
5 F( ]) F  Z, _! v4 T% M; L" `5 D  intersection?   ;; true if the patch is at the intersection of two roads+ ^* Y3 n; q( N3 Q- w  @1 l
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* t* n! x3 g( B4 L
                  ;; false for a non-intersection patches.: Q6 J# B! Z+ f( x2 q+ I# V. z
  my-row          ;; the row of the intersection counting from the upper left corner of the  O/ T" s# p* n+ C" {
                  ;; world.  -1 for non-intersection patches.5 l( X, k" T- w; T" o' C# t" ?# v
  my-column       ;; the column of the intersection counting from the upper left corner of the  m! ^/ M4 n0 {7 ~2 o4 i& \
                  ;; world.  -1 for non-intersection patches.
7 G, R1 m" y' u  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.# s& {2 k" k1 i' _
  auto?           ;; whether or not this intersection will switch automatically.
- D6 }( {" Q( y* `                  ;; false for non-intersection patches.% ]" o  Y" _8 C+ A8 t
]
' N5 g" I: Z- B/ _
) d2 N" u  X+ _* y0 {6 W: K, s# `% x5 r6 G9 T% |# f
;;;;;;;;;;;;;;;;;;;;;;2 R) N" d- l" Y
;; Setup Procedures ;;3 _/ h2 g3 j1 B/ T
;;;;;;;;;;;;;;;;;;;;;;
+ r% [' H7 I* c: R0 i% a; U: d& G8 a1 a" q' @! e
;; Initialize the display by giving the global and patch variables initial values.
$ Q4 G+ _$ {/ {7 R, s;; Create num-cars of turtles if there are enough road patches for one turtle to
- a0 y) y; Q/ T! K0 ]6 S;; be created per road patch. Set up the plots.
8 z/ A# D- i; a0 d( \6 `6 \3 fto setup
, d1 @9 F& |# M9 `% c  ca
; o  J( q9 \3 D+ s1 z  setup-globals9 ?0 f5 q. H/ r

# ~8 t2 d5 g' B# z  ;; First we ask the patches to draw themselves and set up a few variables
7 P) W- u8 H  [, s  r% e$ ]9 v% r8 h6 v  setup-patches* O+ v& I3 Y: J+ V; x
  make-current one-of intersections8 I1 N- i  q/ O
  label-current
2 c% K* S) c! B3 h3 T; C) J& E  L- i
  set-default-shape turtles "car"- ?; M8 x9 `  t3 X' v. t" Z: {3 z& I

9 S, q/ K& u% P  ~2 {1 @  if (num-cars > count roads). R5 J4 T: Q* L' w! v
  [' E( R$ o0 ], H8 e. I) ^3 T
    user-message (word "There are too many cars for the amount of "
. q* d' S& g. K; L3 o                       "road.  Either increase the amount of roads "
7 V. _9 p! ~1 I8 o) ^                       "by increasing the GRID-SIZE-X or "
$ q) `" v( u/ j+ f! F2 x: v% C                       "GRID-SIZE-Y sliders, or decrease the "
3 o: `/ b# o. O! n% ?* s                       "number of cars by lowering the NUMBER slider.\n"2 J6 a, a& X* ~9 M0 N
                       "The setup has stopped.")2 D; f8 A+ j+ V' C$ E$ {4 _
    stop
1 J" A2 y3 t% ^" K/ n7 l, q5 L& D  ]
0 c& N( O3 e, G6 l: G) `8 F/ y% r; e+ A0 p+ H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color: a% n0 a4 X& e+ Q, Y
  crt num-cars
: [) v9 E" p( C  [: E4 {. Z# z; q7 D* K
    setup-cars+ U+ F$ e9 u$ y, c  a/ x
    set-car-color* [" b8 v6 W2 n/ X! L
    record-data, s0 g8 Q( e8 [- h
  ]- p$ p: F4 W, V) r6 x( j

: |& m+ h# d, d  Y  ;; give the turtles an initial speed/ q& }- R  |/ A" n* F- D6 E
  ask turtles [ set-car-speed ]
& u% t' q5 e( ^2 Z1 K( F6 \9 }, Y% s. z
1 w# p! @8 h, k4 t: @  reset-ticks2 f9 ]( H% {0 ?
end
! M+ L* l! E$ ?: Q, v2 E
4 T) ?0 B6 [- u* K;; Initialize the global variables to appropriate values# U) v2 m+ q% P  P
to setup-globals
3 D0 w0 @/ H# t! g; B- q. p  set current-light nobody ;; just for now, since there are no lights yet9 e9 @0 }, y, y2 C& U; }3 `
  set phase 0) \# G7 {; j  Z3 j9 n5 K
  set num-cars-stopped 04 d/ d. Q3 D8 }  [4 }
  set grid-x-inc world-width / grid-size-x
7 w* U2 D2 J6 V  set grid-y-inc world-height / grid-size-y4 h6 D6 L5 v; h2 j
  i5 \7 q% W( Y6 l- [
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
6 V( i" ], G% l9 [& q! m  set acceleration 0.0991 N2 D5 }+ n! n- K/ G
end9 ~. n  N+ ~8 S, L2 D2 {2 ~

7 `3 N( M/ `" |. W4 l- U+ r" m;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ E" a. T9 ~3 e# N# E
;; and initialize the traffic lights to one setting
3 @3 Z# l, b8 p2 l/ t" N: M/ [3 d1 @to setup-patches
% u, V8 @- e; T; U2 O# r  ;; initialize the patch-owned variables and color the patches to a base-color
9 U! W7 K$ ]* S$ H2 {9 T  ask patches
3 g( U0 l: G3 S) R5 J% ?/ P% R  [
4 J' r7 U, B$ `    set intersection? false
& H' o+ M: Y: G! z! F    set auto? false
: R+ g" c) n, \  U; T0 T! ?    set green-light-up? true2 b. w( X, @' |* Q8 T! e2 U
    set my-row -17 L7 \  z; k: i% b; ^
    set my-column -1
. y; J4 Y! K# J5 H    set my-phase -16 z, p/ L) y  |! S* Y# H+ ]; c& A% j
    set pcolor brown + 36 f0 A' p- u2 L1 Q- {% u
  ]
# |9 H! B# G& a5 ]: }5 P1 d9 q4 S% L8 l2 ^
  ;; initialize the global variables that hold patch agentsets: R% w% e/ f+ i3 z
  set roads patches with) z" O( v$ p+ H+ {0 a
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 T( ~7 H% H) }0 |7 [! T
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. [# a- }8 v3 i8 Y( K* f% |7 K' w  set intersections roads with, g9 D1 a3 D. }) l! v/ L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( o" n; W1 E# k. z8 q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. @0 k% M0 s5 w3 @
$ ~+ S7 {- Z' ?; ]4 Y; g  ask roads [ set pcolor white ]
, E: w0 f- z  P0 N& `3 G    setup-intersections& @% I. D9 D4 _, }9 @  @6 t" o1 P
end1 `  e- w/ N4 K8 U2 g4 H
其中定义道路的句子,如下所示,是什么意思啊?7 y" F# H9 f2 u6 S; o
set roads patches with) Y( Y+ v1 e: ^/ U
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. X1 {/ G; j8 m) \' w0 w0 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 D+ a9 \6 |2 Y" ]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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