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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。
! a- p- x$ r$ A; q4 ~! }  ~) k0 gnetlogo自带的social science--traffic grid这一例子当中,
$ }" V6 g& b( b# L* V! [# Hglobals& V+ ~/ `  i* Y/ r$ |6 V8 m  R! o! j$ N
[1 K: d7 l& \4 X$ ]0 b" F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 ^9 ]) S# K( x# b  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 Z7 x) Q$ H% A  }, `  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" [, {6 M. |7 v& V( I' }                           ;; it is to accelerate or decelerate
  L! |8 N8 _/ Z, H+ X: o; m+ v) \  phase                    ;; keeps track of the phase1 j1 a6 o+ M! E7 O) x
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: M6 c$ I7 H3 M+ {5 W) h. I  current-light            ;; the currently selected light$ k9 ^; D: T2 R6 x

4 G( a' F  J* a) N  ;; patch agentsets+ b1 k! X& V! h: i5 ~! @) ?* u
  intersections ;; agentset containing the patches that are intersections
& I8 N" @' s; o) p  roads         ;; agentset containing the patches that are roads5 ]3 ]0 F* t0 u+ R$ I; C2 j. E
]
& V  {- M+ L" @8 r$ p
, U: A0 z1 b4 T' H5 _; Q- _turtles-own
" F2 ?# R. ~& a: X1 s# l" L& Q[5 }. o6 Z7 s+ f5 ^
  speed     ;; the speed of the turtle0 q% |# \4 v- r$ H. Y  g- ?
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ H; c8 F2 o# r2 R% M* ]( f  wait-time ;; the amount of time since the last time a turtle has moved( f" x0 L& Z/ ~1 ?
]6 b: p- M2 ?$ ?/ n% Y% \! R

3 |% W& ]( ]: d) c( w  apatches-own! `) R. r4 L' B- y5 [8 C
[
0 h$ K$ c& ^4 y( Q  b2 B$ i# S  intersection?   ;; true if the patch is at the intersection of two roads
$ |2 k7 r- ~" _0 _$ J, F. W  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ g& O$ s1 y; B0 G
                  ;; false for a non-intersection patches.
2 A- z" ~) C- O2 C' r$ h& o, n  my-row          ;; the row of the intersection counting from the upper left corner of the
0 `2 B! p4 N8 r6 i" j6 M- y+ C                  ;; world.  -1 for non-intersection patches.
* z; f" ?* a5 m! a  my-column       ;; the column of the intersection counting from the upper left corner of the9 a5 g1 L7 a$ W' N" H+ |6 q
                  ;; world.  -1 for non-intersection patches.0 F8 \4 N, B7 [; H5 i
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
& _7 `9 p- w6 o- e& T' }  U  auto?           ;; whether or not this intersection will switch automatically.
* l( J- e+ K+ K7 F  j% T- ]                  ;; false for non-intersection patches.
* a5 W8 {' V6 u- H* [3 T! t: n' d]
( u' C- J- f% H9 Y' r! ^5 k' y5 I, f, F$ Y: ]9 q

4 p1 q- ~; f( N' S6 ^# R5 F;;;;;;;;;;;;;;;;;;;;;;
5 k5 |4 Y1 s, \% ^% A: b. x;; Setup Procedures ;;
( `1 _/ l0 W& Z( G. T;;;;;;;;;;;;;;;;;;;;;;& F2 H8 {) ~$ N

6 s- T6 {6 k# I;; Initialize the display by giving the global and patch variables initial values.
( e3 R: g% `% [( i9 P0 M  {6 q;; Create num-cars of turtles if there are enough road patches for one turtle to
" t8 P9 |, b& u;; be created per road patch. Set up the plots.* g. i, [' ~& t* K. `5 ~' s, I+ Y
to setup! ?9 B4 j3 C- t. X" E
  ca, e9 a+ B) U; ^) o2 s
  setup-globals
" e& W' j6 z$ z6 G) H  Q7 u  x/ M9 ?. F; s
  ;; First we ask the patches to draw themselves and set up a few variables
- b, t/ Q: j! ~  setup-patches3 b8 h6 m8 @! z1 ?) S
  make-current one-of intersections
+ t+ G; \2 b8 ]5 k. ~  p+ c, X  label-current
1 f, u" ~9 [" m1 _
! k/ N' |: S/ ^' E1 _& k' ^/ _" X  set-default-shape turtles "car": r( M( ~! d- c5 _! v

* F' {: m* c, o1 K2 j  if (num-cars > count roads)- P5 Z; C1 ~% K
  [" i: H5 {( b! p/ n- P
    user-message (word "There are too many cars for the amount of "
5 n- y9 |1 @8 C- B) A' r3 H& l                       "road.  Either increase the amount of roads "
! e: K+ j8 F2 M$ i                       "by increasing the GRID-SIZE-X or "
, q: `  v5 T2 ~; E1 B) n                       "GRID-SIZE-Y sliders, or decrease the "1 f+ n% L" y/ E; D0 X
                       "number of cars by lowering the NUMBER slider.\n"* p4 Y8 |" K+ M% g' n
                       "The setup has stopped.")
6 `1 q* \8 i4 ~% @) H1 p    stop
; B9 W4 a* }+ p: K$ A. f  ]
: n9 i9 b1 K8 I$ t, M) f  Z! ]" |; G! Z6 s) Z7 j
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color' U& h# V4 p  N9 {  p4 I. d: a
  crt num-cars
* B4 l5 Q+ E, b& l; C) R  [# w1 ?0 E  A9 R) i/ u
    setup-cars
; n2 u$ k3 K- A" K; [    set-car-color: g3 Y% H' f, f5 L
    record-data
5 H. E" |( w! q0 w  ]2 d! v4 O' S* q
! ]: h$ m7 o* k
  ;; give the turtles an initial speed
. d5 _2 Y% u3 C$ e6 Z  ask turtles [ set-car-speed ]
5 }% ~7 O9 G- A) l9 }- ^' A' i8 h0 C5 g/ D
  reset-ticks
+ v' H+ t% F! mend$ I1 R0 l3 S" X( g5 @& L
( Y$ L$ U2 H) i% G
;; Initialize the global variables to appropriate values
6 Y! c# t9 s5 z' O) T  Sto setup-globals
( l* Y& O- ~  |7 k) @  set current-light nobody ;; just for now, since there are no lights yet+ z- b* J3 `; Q  W$ B/ }
  set phase 0
( G' V, {3 I8 \  set num-cars-stopped 0
; K) Z. T4 j& X9 y# \* h5 w% I9 [  set grid-x-inc world-width / grid-size-x, \' [. J7 t- Z
  set grid-y-inc world-height / grid-size-y/ y1 K+ ^+ b! Z; G

/ Y; A% R* T) z( @  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 U1 b( O% {4 k7 {, `. @  set acceleration 0.099# h; ?1 a# `& ~
end
- {$ c3 `2 P, L, {! X3 f- \; d
0 z( j* t5 n* V, ~7 O8 Z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  @; H5 U' D. @" N( ~5 Z) u;; and initialize the traffic lights to one setting
8 [0 i) {6 _! V  }. zto setup-patches, V5 F0 V3 o" p) d0 m5 Y8 s
  ;; initialize the patch-owned variables and color the patches to a base-color
2 i  {0 ?6 L$ v" N! |  ask patches
0 h. X9 N; t) [! M. l8 P  [# d6 S7 F& U. b6 F- w! ^9 u( }
    set intersection? false/ j0 H7 @9 V+ N
    set auto? false( {/ F6 o1 ~: ]
    set green-light-up? true4 W! @4 P0 q  {0 M
    set my-row -10 l, G( j  ?+ `* i: c4 G
    set my-column -1
# R2 I  ?, Y1 p3 r) ]! {' U    set my-phase -1
% f) {3 p$ g# y3 f! {  t    set pcolor brown + 3
% H3 i5 q: ]+ [  ]8 g3 x* M# C, z3 k1 p6 X

- M* K! C+ \2 J/ p, ?: Q& Z  ;; initialize the global variables that hold patch agentsets
, Q4 y: A, I9 x8 |  set roads patches with
( H9 O) s, }8 j! I! A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 Q  I9 p+ p- Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" N$ R, l% S) N  set intersections roads with# Z4 k2 \. y: \; z$ i
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( @0 d& V2 h! Q7 q9 q; z' E    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 A0 w+ {& Y2 @, t8 Z2 ]2 k0 \2 r  _+ U& C7 d9 v; l, B
  ask roads [ set pcolor white ]7 o& `9 R9 N5 G3 @) e, ?; G
    setup-intersections
1 t+ h$ u; B6 z$ Xend& j9 d0 p, s3 E2 Q3 ]% J
其中定义道路的句子,如下所示,是什么意思啊?* M( y5 U" ]1 @& O! Z4 E0 Z
set roads patches with
, f6 P: R/ R  R    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, h- w' }- a: X5 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 g* J4 V+ Z! q& p  J4 A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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