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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。" o) R5 n( ~& J/ Z7 O5 h
netlogo自带的social science--traffic grid这一例子当中," B( g0 I% I( M  E5 \+ n6 D6 D6 u. X' Y+ ^
globals+ T1 a; R9 ~+ `" ~5 J7 F! F
[
6 {- E5 E; o2 ]$ ~; C  grid-x-inc               ;; the amount of patches in between two roads in the x direction" P8 E6 x6 t3 k3 K
  grid-y-inc               ;; the amount of patches in between two roads in the y direction! L, `- |6 S( |6 T' p8 k5 H$ m
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  ]/ y1 S& y5 W* Z) L0 `
                           ;; it is to accelerate or decelerate
  |: {9 n: B! \+ L- o' d( Y9 ~2 D  phase                    ;; keeps track of the phase5 Q0 j3 J1 m1 N2 |, j6 ]0 H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" D: @1 F' c1 X9 L/ F! e6 w
  current-light            ;; the currently selected light1 J- I# c9 r/ j9 u5 j5 G' G: L
9 f# p" ^& ?, C; C9 ~$ h  c% l
  ;; patch agentsets
9 Q; d6 K& o; N* Y* I; p) T; g  intersections ;; agentset containing the patches that are intersections
1 L2 I7 t7 m0 O3 ]( s6 T2 O- @5 |  roads         ;; agentset containing the patches that are roads
, ~! n# y) a' h7 m/ s' e1 A( R]! j' v+ v$ j* c
' U- [# J/ \9 ^, u
turtles-own
1 |! _% A6 ^3 |% l9 K1 m[+ d% n% [- t0 H/ @6 c
  speed     ;; the speed of the turtle
: @. l, p' T) n1 n( c  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
; E( i2 B; [% m3 A  V  wait-time ;; the amount of time since the last time a turtle has moved
' ^% \' Y9 O6 U3 u]" ?" m1 r" I0 X: d

' {3 \3 ?( h$ |patches-own
5 w/ g$ f, M: ?) {! d! n% }[
+ G! k8 v" u. s( {6 X+ D( T. x/ s  intersection?   ;; true if the patch is at the intersection of two roads
: ~, U; ^- s% L3 h* H! h( U  U  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# M7 U" F3 K. M3 a                  ;; false for a non-intersection patches.6 n" G$ T+ j* J+ ^* r
  my-row          ;; the row of the intersection counting from the upper left corner of the" i) t# H& j: I* Z4 \$ ]
                  ;; world.  -1 for non-intersection patches.
! E+ z4 P) \- F6 Y* {6 F; F  my-column       ;; the column of the intersection counting from the upper left corner of the
. E# C! |5 d( s; G                  ;; world.  -1 for non-intersection patches.: o- ?9 T& [: C# g" X: Q
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: v* \/ c6 [7 W/ W
  auto?           ;; whether or not this intersection will switch automatically., i$ e7 O7 S+ n
                  ;; false for non-intersection patches.
- d# D# y7 V5 a9 i]% Q) D0 {* Q/ S- h) l* D

* y9 ?/ B) P  f3 P# R- ?- y0 m8 I, F
8 I' w5 i* t3 l* _; E1 l;;;;;;;;;;;;;;;;;;;;;;4 Z/ f* x( C. l" U6 Z2 `+ D8 K, ]
;; Setup Procedures ;;1 ?* S$ x4 [6 w% C2 b: O, f( D
;;;;;;;;;;;;;;;;;;;;;;7 ^2 N& N: I$ t' e6 }
4 }4 n. L5 U, B; X: q( h. D
;; Initialize the display by giving the global and patch variables initial values.
8 q+ c7 s8 [/ E. f;; Create num-cars of turtles if there are enough road patches for one turtle to
8 K2 G' G) _) `' t5 J% `;; be created per road patch. Set up the plots.
( D1 _0 `' b. t- Q$ x9 }to setup
: {- p% V9 L2 v4 d  ca  r7 r8 c# A5 }6 ^  e, X3 _
  setup-globals& n4 f1 ]( w) d, u5 }* j

& b; Q4 T( U% Q  ;; First we ask the patches to draw themselves and set up a few variables) _8 w4 U. T' x; o
  setup-patches
; V7 P2 S$ K( j0 i  w  make-current one-of intersections
  l5 b$ f! L8 f9 z  label-current
, E' g7 H9 ?( x7 n4 {& n+ S+ V: u" O
  set-default-shape turtles "car"
" f# I! k$ `# T* }# K, t
1 ?- Y# q% c+ K- p! C2 U- f  if (num-cars > count roads)
# ~1 Q% M0 e' a/ i+ A7 q  [
: n; u* W. c2 c- F( t- i7 T    user-message (word "There are too many cars for the amount of "
) i6 C, ^/ O7 {, I7 e/ _7 X                       "road.  Either increase the amount of roads "% f6 W, }1 t8 F& L7 Q5 U( U3 i
                       "by increasing the GRID-SIZE-X or "
8 L7 z! K# V: t. ~                       "GRID-SIZE-Y sliders, or decrease the "6 T7 ~. v4 P4 l. a
                       "number of cars by lowering the NUMBER slider.\n"- ?" w. A! v$ X8 L  P( A" J( I* W
                       "The setup has stopped.")
2 J+ c5 X- U& {    stop, C; m& U( r8 j5 @! o" m$ a: G
  ]% k6 P! D2 L' p, Z. r

* X1 i' j2 u7 R0 u8 d8 c  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
. i8 R0 A( V! {; l& D  crt num-cars" k4 c# d, o) [2 @3 e* \
  [# a% K) o0 U4 y/ \1 R' Z5 z) P
    setup-cars4 m- h2 f& c5 J( s% \" Y+ @
    set-car-color
. |- E0 g0 q% ^# r% c    record-data- q" |# ]' c+ B* R/ R
  ]; _; @: ]0 Z1 c! f6 [) p+ S
1 y" K7 w( |% r2 o$ {. h% m
  ;; give the turtles an initial speed
; O! m5 G0 y. w0 q# D5 \" e. `  ask turtles [ set-car-speed ]
. y' }" I4 I, G( r1 ]
' K" T) {1 }& v; Z; r/ E4 h  reset-ticks1 q3 D) ^7 G0 ?- N8 ^
end
) J$ j( E8 r* h# }! J( d
( o9 E7 W/ @) v. f5 m;; Initialize the global variables to appropriate values7 u. {6 ?  d$ a5 i" B* m
to setup-globals
2 Q" R: y2 p% ?  set current-light nobody ;; just for now, since there are no lights yet% e4 b: f& h) M* H+ g+ I
  set phase 0
, D8 C3 G/ J: {" O0 l' S  set num-cars-stopped 0  J( j9 m7 B" t
  set grid-x-inc world-width / grid-size-x
* E" E! F8 P" a( O$ a; l- B5 u  set grid-y-inc world-height / grid-size-y  N4 N: u$ \) d8 @5 P0 {. Q

1 B& b+ m2 T7 p0 H  A/ q; ]  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; X% W$ {  z6 f! U& X7 ~# K% w5 S  set acceleration 0.099
$ N' d7 `; ~% y7 z/ t, r% R# _$ Z9 kend
# n* O' }. |" o
8 s, g( e3 M/ F7 \: E3 S;; Make the patches have appropriate colors, set up the roads and intersections agentsets,2 @. O! @: o% d9 V% ~* f
;; and initialize the traffic lights to one setting' a+ o- |* M4 O4 X- m. m8 p
to setup-patches" b5 I. Z4 }9 d) B2 w. _% t
  ;; initialize the patch-owned variables and color the patches to a base-color! C: Z( J  n9 o- X2 c& i4 S
  ask patches
8 J% |( L) C( t  [
: j; a5 ?3 D6 `' i) `* h3 ]5 N    set intersection? false$ y9 o9 y; z: `' p2 f2 s
    set auto? false
9 R# [1 _; r; }    set green-light-up? true
9 s2 L0 D! l, y4 Z    set my-row -1( @5 h! t8 {- D6 F) H
    set my-column -18 D$ ~3 `/ U: |3 p1 a6 e
    set my-phase -1/ D( y3 t5 w0 h. l  A' z
    set pcolor brown + 3& W, J  C4 M! o) n3 ^. M& x
  ]# N4 U- k- T0 G5 d& F

" j6 u6 k5 n# e# k$ w  ;; initialize the global variables that hold patch agentsets& f( P# m" M/ [* X5 k1 N
  set roads patches with$ P% g- ?* |" B. Z  y3 n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 @2 J& A  @/ D/ S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 l; K- Q0 H, D  H) t7 i8 _
  set intersections roads with. P! O4 W  X+ @* g: T% P; ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
! d: s1 i# S7 t1 L& y6 @    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. K. L, |; D: f# X8 |0 y' |! w  ]- O! l) t$ ~: ]: P6 y2 o
  ask roads [ set pcolor white ]( q) J' W$ @8 s
    setup-intersections
/ }* F( o- ]1 s) a% `4 jend
3 i$ }6 G* K: m其中定义道路的句子,如下所示,是什么意思啊?% g  W/ h. }! h" y) Z
set roads patches with
9 Y  _, f$ F, `& c( m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or% A/ `! y! h& k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* q+ E9 n2 V) O; n! i" L7 H! {1 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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