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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。( f" m. m( O/ O8 B
netlogo自带的social science--traffic grid这一例子当中,, g: c8 i! j# I" t3 K1 m9 p
globals+ i* X% i% T" X6 l; B* e
[6 Q8 x( G; {9 s1 u& i$ K$ o( O
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 y' f5 o$ @7 x4 r  x, h. B) a  grid-y-inc               ;; the amount of patches in between two roads in the y direction
  E/ M6 r8 ?1 I9 K5 F) P( C8 ]& b# O  acceleration             ;; the constant that controls how much a car speeds up or slows down by if2 {- P* _0 W( e5 C; y/ P: X, L
                           ;; it is to accelerate or decelerate: G0 G1 h/ L( }, X6 i1 U
  phase                    ;; keeps track of the phase
- R8 ^) {' O1 |' Z1 ]  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 I1 U2 ^* i. A+ f' J4 d2 `! a
  current-light            ;; the currently selected light
0 k  X  S; N. \) h$ |( x3 ]3 r5 D. Q/ e' k
  ;; patch agentsets- R( z; A0 M7 k
  intersections ;; agentset containing the patches that are intersections
- ?5 x" w( m6 d8 c  roads         ;; agentset containing the patches that are roads
# z4 E' U. M7 t( Y]$ T( ~' u2 \' {5 N2 V

' M& t  F. u( `& P3 f- E6 v& U& Gturtles-own
! J6 t5 W3 x3 M1 g2 ?' P[5 o! F& d" [8 o$ v5 T. y0 ?
  speed     ;; the speed of the turtle0 z7 d& o$ e2 Z5 j" ?; T
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 S+ W% G6 _* [6 x; ?
  wait-time ;; the amount of time since the last time a turtle has moved3 J& {8 u, U" L) T/ p) v1 E7 Y
]' H4 l: R" d, _' ~8 F
+ `# ^0 [9 z8 d+ n- ]
patches-own1 N+ C+ F  I9 n" W- U
[
- {0 v- j% K5 W1 O5 |  r; b+ k4 k  intersection?   ;; true if the patch is at the intersection of two roads
2 d& G1 d" A+ x8 B  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.5 T% v# a3 q( x8 I* P' y2 v: y/ a
                  ;; false for a non-intersection patches.- J; v* g/ n* M) c) w$ G
  my-row          ;; the row of the intersection counting from the upper left corner of the
/ F5 ^1 |, s/ |2 f. E5 d9 N1 \' T                  ;; world.  -1 for non-intersection patches.
1 `0 `# e# E4 ]8 y8 p  my-column       ;; the column of the intersection counting from the upper left corner of the
, }5 N4 [8 j) y0 n2 l                  ;; world.  -1 for non-intersection patches.8 Z1 Z- [9 H/ R7 @. Z+ r
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! _, p7 F% P$ R8 M. r9 L/ k7 b4 @  auto?           ;; whether or not this intersection will switch automatically.% g3 o- e7 r. z8 w) X; P
                  ;; false for non-intersection patches.' B. w0 m& S$ X4 W* O
], g. n+ m$ \' l) ]
& E. ]8 Z+ O* Q- z( C& a+ H

2 P: v7 ?3 u. B;;;;;;;;;;;;;;;;;;;;;;0 Q) ~. F+ p3 W
;; Setup Procedures ;;
0 Y, T* _: P( K* T1 P  B% J; _3 q  z$ j;;;;;;;;;;;;;;;;;;;;;;+ K/ g* m" p) l( \% W. @

5 ~9 R" O- O& d;; Initialize the display by giving the global and patch variables initial values.0 x7 n  {4 z- ^) ^- G* x
;; Create num-cars of turtles if there are enough road patches for one turtle to6 C3 W1 [& v! b) P6 ^0 z- |
;; be created per road patch. Set up the plots.
/ [4 r  G; L8 @- @- Lto setup
* j6 X+ u; _! I8 Q3 i* f; D$ B  ca
6 M9 V" P' H0 M3 n2 C2 z; F  setup-globals+ l- r3 H- f8 Q: G" j

8 f/ n5 y& U/ L2 c2 B8 B- _& E6 D  ;; First we ask the patches to draw themselves and set up a few variables7 k2 w. r/ U- {& J1 R
  setup-patches- o8 K0 r6 I7 A; Q$ R/ l
  make-current one-of intersections6 d1 X( I8 R1 d
  label-current7 u% V; T, N+ E& `% X. ?
9 f5 E6 _6 ]( U& E. q7 B7 k
  set-default-shape turtles "car": u5 Z$ f4 r) J* D( Q

5 D0 D2 l% z' ]0 h7 n- O. ?7 t  if (num-cars > count roads)0 f; n9 O7 `* j; M/ _
  [5 t  E# x4 b  l9 Q& Z0 h
    user-message (word "There are too many cars for the amount of "- K2 B2 p3 X. U# J0 a+ |2 E7 Q
                       "road.  Either increase the amount of roads "; D0 h" Q1 Q1 `. m
                       "by increasing the GRID-SIZE-X or "
; @6 t4 F0 r# q# H- y$ g                       "GRID-SIZE-Y sliders, or decrease the "
: i, f3 N) t% j2 y) g! c4 n                       "number of cars by lowering the NUMBER slider.\n"
0 v8 O. K) [+ w, y                       "The setup has stopped.")1 e6 f# d9 v, R7 c, E  N0 j
    stop. d7 E/ B1 J$ q/ o. ?: }
  ]) q8 }* ^" Z9 V. f% F2 s* x" B

  H) R& A. N6 t# H$ i  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( D5 m. a5 h* n; i
  crt num-cars  ^, v) B7 [) I& k. G4 A
  [
0 E/ z* ]7 `) \8 H    setup-cars
  L$ Y& \; |4 v    set-car-color
: G7 ]) _+ m9 e* y& h    record-data$ U5 C' M, s; N* l5 h
  ]! W: K+ V& Y8 S- Z; J" P) p

# u- M3 o. {) S3 S7 q. O* z/ J  ;; give the turtles an initial speed, g8 I& c& _# K' b" t+ s3 ]: b
  ask turtles [ set-car-speed ]" w6 r1 ~5 }/ r0 F6 y

0 Z3 i8 `( r: N! x  reset-ticks" O2 A- ]7 {9 j. w" U  ]  b
end4 n, |5 ~% P  G, @* J

3 d& W0 R7 ]+ i% v, Z;; Initialize the global variables to appropriate values
- b% [2 }0 \( M2 M; g. A( N1 Xto setup-globals
& z6 K( W% u+ c9 Z0 i  set current-light nobody ;; just for now, since there are no lights yet
& I( n7 c% {6 b. ^  set phase 0
7 X2 F; A0 ~, g9 E/ m  set num-cars-stopped 0  F8 t' e7 M! Y
  set grid-x-inc world-width / grid-size-x
' H7 W' D4 J% M- ^8 b  set grid-y-inc world-height / grid-size-y
. ?' [, R5 ~  Y  v. ^& n+ j2 J" _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 K9 W7 d- ?$ Z& }# T% `  set acceleration 0.099) i5 B' Z; V! V! k5 Y9 ^8 b3 l
end6 w; h( M6 Q/ ^- ?4 F# a7 u

8 t  n- w: Q! z" o2 z, E& F; H1 V;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
5 p9 g- k+ U' |3 \- t& S;; and initialize the traffic lights to one setting
" L. ^/ X6 X8 S7 k! r, F# Y/ F% `  zto setup-patches! F0 m9 `- k' Y5 o# F9 ^2 b8 ~# |& \' }
  ;; initialize the patch-owned variables and color the patches to a base-color0 p+ Y& r& D+ `: ?! \
  ask patches) y8 _0 B/ M! ], A. t4 m; l
  [
5 L2 r2 [% {* K  j    set intersection? false$ U' J' `; k" x, h
    set auto? false2 {% F2 |% U( t+ ^* I' t9 l9 @
    set green-light-up? true( F- a# ~1 E9 l6 k
    set my-row -1
. \' F/ D/ O- O( g3 E) C4 S" g    set my-column -18 o" Y. `. E. C7 Q
    set my-phase -14 v) p1 T( `8 i1 s3 I
    set pcolor brown + 3
/ h1 a* X) Y- U7 C  ?0 V  K  ]' H: Q( g: K" c# A
% f& ~, V- J9 V! v
  ;; initialize the global variables that hold patch agentsets
% C( G2 ?& E$ C, e7 F" ]. O  set roads patches with# V$ M  c4 i- ?0 @
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& |2 [3 T  {& K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( I/ S+ @, ~' x) ?- X  set intersections roads with% I& N9 h) W' u5 ~
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and4 E# s; H7 L+ ^: [* i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. z9 k# a$ A. J" c4 f1 r9 W
9 q1 m; V- M9 }, x
  ask roads [ set pcolor white ], A  S* F$ i2 z8 j- b
    setup-intersections- m( I! p% X3 q2 Z; U# w& ?
end
) z$ `7 @4 `' e- \( F0 W8 l其中定义道路的句子,如下所示,是什么意思啊?: {$ Q" q/ O9 y% y
set roads patches with
0 }1 i3 P% x7 w& o6 N& a    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ G  H; p1 O1 t$ H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 i0 l  D; q. F' U8 h- 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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