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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 M2 w3 P/ G" ^. ^$ m' h. g7 }
netlogo自带的social science--traffic grid这一例子当中,5 X  R! Y' e  W3 ^5 O. J9 O0 ^
globals4 m0 y0 s  A9 @6 ]; K5 q& }7 |5 B+ Q
[7 E6 z& X9 Q4 d7 J% X. k  J$ i
  grid-x-inc               ;; the amount of patches in between two roads in the x direction. h  @: _# x! a3 I) D2 D5 A
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 y0 L! T, N) }% Q8 R  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 K2 r8 E1 \! n! y1 |- `  ^
                           ;; it is to accelerate or decelerate2 r9 g" n( G! N8 ^
  phase                    ;; keeps track of the phase5 h' Z4 E; I# o( h9 |4 t
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure. [9 s9 U# U; B7 C& F
  current-light            ;; the currently selected light
& M& g$ x6 |  h* f  B
. I* A6 @- i1 Z: t# X) M! C  ;; patch agentsets
8 e0 _. w4 q: j* x6 i2 A, a  intersections ;; agentset containing the patches that are intersections9 b' y- b9 T: \
  roads         ;; agentset containing the patches that are roads
. G) p3 D, I6 H# |) i]: u" t* G" e5 y# c! x
9 V$ T4 u9 f' D% A3 [- J  v# l7 K
turtles-own
% m% \  A% W* {- z% \[" k5 u# y  Z% ]4 ]
  speed     ;; the speed of the turtle
) d; z, ]9 `9 G9 B' M0 S  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: M- o4 M9 @. ?! m0 y
  wait-time ;; the amount of time since the last time a turtle has moved( `6 v) \4 O% L
]' [' U" V, k1 r, [

, }6 N( p6 x# O6 T9 ]patches-own6 L! n; P; k: U$ s& c( k; K
[" u0 _0 p2 O& o7 y
  intersection?   ;; true if the patch is at the intersection of two roads
- ^8 ]  H* k. H) T& T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
1 @4 u# j" I4 f& k2 u7 ?! P                  ;; false for a non-intersection patches.$ x0 h: p  N$ Y  a6 L& p
  my-row          ;; the row of the intersection counting from the upper left corner of the6 W. A7 x5 j3 k1 D2 ?0 A# S
                  ;; world.  -1 for non-intersection patches.5 u$ E3 A, j5 y! F: R' l
  my-column       ;; the column of the intersection counting from the upper left corner of the. h' J; Z; z  t! ^
                  ;; world.  -1 for non-intersection patches.
- K' D# N$ Q: }5 R( b  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
. @& v/ T" i0 {+ m* h! n, Y  auto?           ;; whether or not this intersection will switch automatically.
2 y* f$ _9 f6 x' X. x                  ;; false for non-intersection patches.
) L% _' [' f& }]
. c- M) @3 f' t/ n1 c) v! {9 F( m# M$ Q
8 x; {7 l/ S& ]
;;;;;;;;;;;;;;;;;;;;;;
* v, c0 |9 A1 e& N, k7 s; a' I;; Setup Procedures ;;! w8 o6 Z' ~. o3 v- l$ j5 D1 o
;;;;;;;;;;;;;;;;;;;;;;
, @7 M; p6 s0 b% v
3 g/ F' }( P2 g$ `9 j;; Initialize the display by giving the global and patch variables initial values.
7 D6 d7 z- d5 c! g9 H  i;; Create num-cars of turtles if there are enough road patches for one turtle to
: K" ?/ @9 o4 u  C;; be created per road patch. Set up the plots.0 T) C0 V9 X% X/ X. k, ^
to setup/ l7 m5 Z" W# m2 E( w7 G; Q
  ca! i5 f* ~, U3 X0 |$ s& P
  setup-globals
$ N1 R0 I. `0 g- I7 ?! G8 E% b
' i4 W; V8 b( Q& y8 k  ;; First we ask the patches to draw themselves and set up a few variables
- l8 V" i$ M* ?" I: M# {* L  setup-patches* {7 c' q. i% {7 U0 ?4 B0 B
  make-current one-of intersections; s7 o$ ~& d% r" Z9 R1 Z; I- a
  label-current* O( M5 O1 y. H0 R' Z& v" I
( `/ \8 y% f( g# k1 P
  set-default-shape turtles "car"
/ l+ z) E& Z" m; L/ [  `
/ H9 }0 M& u9 w* [! M  if (num-cars > count roads)
( c5 F& [: S, ?5 I0 v* \3 X' ~  [
5 ?& E0 u1 z8 ~' O$ v4 T    user-message (word "There are too many cars for the amount of "
# ^6 k, A+ y+ h  [2 P' a                       "road.  Either increase the amount of roads "- ~5 f& ^# V3 V) @, Z
                       "by increasing the GRID-SIZE-X or "
8 U$ Z: C+ b6 `                       "GRID-SIZE-Y sliders, or decrease the ". C, Q. ^6 p  L- l) @# n
                       "number of cars by lowering the NUMBER slider.\n"
- N! K8 y- s; z                       "The setup has stopped.")! q' X" v4 s4 s* R/ p5 P
    stop
$ t& o+ F. b% |  ]
  q* r/ j" z6 a" `8 Q) _/ B- m6 T, t. c- L* f1 r
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# n' D7 x8 R/ j3 I# K4 Z
  crt num-cars
* e$ N' Q( c% @' r  [4 f; X1 r$ B1 X# I" ]
    setup-cars
: T; Q: I5 @$ K$ V7 E6 Q    set-car-color
; l5 U9 T" v, g% ?, L2 n+ g    record-data% r) V' z5 L9 Z  o
  ]+ G/ E6 p# a$ X: _

$ c7 k9 ?; A$ D8 G/ K  ;; give the turtles an initial speed
/ L# B/ Z; d0 w" r( v( Z  ask turtles [ set-car-speed ]
( I7 D3 ]4 [' \* o9 Y( x2 i. g- Z
+ ?$ q; B* }. C4 h7 A3 M8 c  reset-ticks
. D3 n# `) j$ I+ Q' t. ~0 a! `end7 q, u1 E* D! P0 N4 [2 y5 e
% y% ?: a8 Z6 t
;; Initialize the global variables to appropriate values- F) q) T  w# f( Z* m) O/ h( ?- |
to setup-globals
: o2 G. j  {$ _- t: z  set current-light nobody ;; just for now, since there are no lights yet0 b2 ^! {+ _: q7 i7 z" e% n' P
  set phase 0+ w5 r" F5 \5 a' D1 D' B. [
  set num-cars-stopped 0  N% Z! B. f! R3 E. L
  set grid-x-inc world-width / grid-size-x
; J; r2 o$ P' P( Q; J$ i6 i2 [  z2 z  set grid-y-inc world-height / grid-size-y! |- `% O) P' e4 e. u6 M: C% H
+ J& m# W  V# U9 N8 C# j
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ s( n2 j6 H: p. y* |+ ^  set acceleration 0.099
1 c8 J6 m) X( L& q: c$ hend
2 e% a4 |4 z7 R4 }% ?' M% e2 r
" R! B( t+ {8 t& ^;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 `( I1 F* q' Z# |3 U6 d% y;; and initialize the traffic lights to one setting
0 ?/ H$ f: u" dto setup-patches* m  o# a+ U. Z! g4 D  J/ ]* ^
  ;; initialize the patch-owned variables and color the patches to a base-color) b7 R, H4 y! C: J
  ask patches' g/ [- _3 G3 N
  [
7 X8 ^/ q0 |- T, |* D    set intersection? false
  ?$ c6 X* f. A- z6 G9 E    set auto? false8 w7 U$ B* }: v1 ?
    set green-light-up? true
2 R8 ?: t+ m7 w/ R- H4 [8 X    set my-row -1
) |7 n- z: h# V$ S/ n( [4 S    set my-column -1
0 k4 u9 h0 `: v0 l5 o4 q$ Q) {    set my-phase -1
9 S" w# M& U2 g: z& O    set pcolor brown + 3
+ m. ~# h/ g. [7 B4 f. M2 S  ]: U  ]: D  s' y' f- L- l2 R4 ?

: [* w& N4 {( E+ z0 k: G  ;; initialize the global variables that hold patch agentsets
) [/ Y; Q( @9 x9 Z; p7 Q  set roads patches with9 K' p) t' M) n& |9 P" x0 Z* ]8 M/ _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or0 k: D, N" g4 y2 O
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
. e! z& k2 _& q0 z  set intersections roads with
4 Q9 ?3 N' g( b  l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( [% F; t1 H! J. }7 I6 l
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" i) y! g, L5 I" v* M; x
4 g/ J( V4 L1 B$ [7 ?; E6 m) k" U
  ask roads [ set pcolor white ]
+ r3 E9 j" y! K    setup-intersections
+ {+ C3 P6 i/ V. z( u1 l" n8 Gend1 R, j& I, q' h  Z6 X+ e  g
其中定义道路的句子,如下所示,是什么意思啊?
: t2 [' ~( u0 w; } set roads patches with
# b' z3 w0 {. z2 w8 j7 O7 Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or2 n; @7 [+ h$ |, u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
# \# e" i, q! R3 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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