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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。
/ F8 c: j5 b, Y! f0 C( Bnetlogo自带的social science--traffic grid这一例子当中,
/ u5 P- M: k- o; D  uglobals
3 ]! ~# C' P7 }5 L# w' ~[
: E2 p2 a% S5 Y( E  grid-x-inc               ;; the amount of patches in between two roads in the x direction4 T9 q6 f1 t. l2 c$ s' |: E
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 N/ y5 o8 c$ F. P" Q& f6 q" N: U; K' F  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 c4 K  G; u$ @
                           ;; it is to accelerate or decelerate
- a! T# I: X9 d4 `7 k" o  phase                    ;; keeps track of the phase
+ C' J7 b. G/ r" r+ A: [. h8 I  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: H4 T; h( l( }3 X* s: o. M  current-light            ;; the currently selected light
8 T7 ?0 R1 w7 ^6 h" K: T! H8 ^0 ~
  ;; patch agentsets
1 ^. s4 D+ ?8 J# o8 l9 ]) B  intersections ;; agentset containing the patches that are intersections7 \/ z# I3 P" I1 V' n4 _2 @
  roads         ;; agentset containing the patches that are roads5 N. l) C* `0 @" a6 F- i# p- C
]
; j  q* @4 [: R- U  ]" W  ^2 y% l/ K: Q, j! u( H
turtles-own5 N/ r& v! s+ ~/ e  T5 e
[5 k, k' ]5 u7 _7 t
  speed     ;; the speed of the turtle+ k8 d# X+ y" ?9 N$ N4 d
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right# q% z! p- y6 M4 z. h
  wait-time ;; the amount of time since the last time a turtle has moved
! L/ z& l. {& a- a]7 J5 |1 P& v. J+ C

7 b6 y( a2 ^' x5 o) upatches-own
- X7 g7 U7 m6 _% b[5 v, s% z" D8 m
  intersection?   ;; true if the patch is at the intersection of two roads
# E, i+ t& @" l1 ?1 J6 d1 T( ~  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 u' Q4 c- x) B% X0 A
                  ;; false for a non-intersection patches.
" C; I3 c0 \4 I0 |1 X( i  my-row          ;; the row of the intersection counting from the upper left corner of the
5 _9 [5 B% Y& l- ?1 G7 z: w                  ;; world.  -1 for non-intersection patches.
0 l' Z, f: }* D  my-column       ;; the column of the intersection counting from the upper left corner of the8 Y8 ]( b' Y* s
                  ;; world.  -1 for non-intersection patches.
* z; I$ D+ t2 [5 l0 D' @  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" V0 ~1 J, |( R0 A  auto?           ;; whether or not this intersection will switch automatically.
. ~2 H& N2 c! f) x2 S                  ;; false for non-intersection patches.
1 g5 e5 V- V1 e/ W5 q]
8 O! C) _; M% A, U/ }" }( [5 Q& s7 @' e1 ~; l
) h% n+ D! d. z% s: B/ k, ~
;;;;;;;;;;;;;;;;;;;;;;$ f; o3 d: D0 a4 D! _6 g: V! W
;; Setup Procedures ;;
7 Y1 Y: p1 D8 B/ _;;;;;;;;;;;;;;;;;;;;;;
  O/ m7 m( r5 u$ H) b, O* K: b$ H9 g6 j. @
;; Initialize the display by giving the global and patch variables initial values.
, k) ?/ O: G; U  M# J7 d;; Create num-cars of turtles if there are enough road patches for one turtle to
7 m2 i3 W4 r( \; ~: o' g  [) S;; be created per road patch. Set up the plots.+ f" `" m8 @1 ~
to setup1 E' _3 x. |: b& @1 l" ^
  ca
: I0 O/ I' ~, S. w- w8 k+ C9 O: l  setup-globals
0 e6 S5 A4 ^6 t0 m7 }* l" ~
7 Y1 K. U1 b3 [' B# I' R/ r0 t* y  ;; First we ask the patches to draw themselves and set up a few variables- v$ V% B$ P9 g6 E- X
  setup-patches4 C; Q9 U# f) }4 V* H' D
  make-current one-of intersections7 ^2 s" b2 H6 o, o, `- o
  label-current! c6 ]/ n$ S; c9 u% c

2 @5 U" j1 Z# [" p: _  set-default-shape turtles "car"
7 ?* G! i2 s3 o4 K' A! W, v
6 ^* u# b" _  o5 C* z8 t; l% E  if (num-cars > count roads)( ?7 F( j; Y2 g6 c, a; Y+ V' j8 @
  [% N! K. ^, ]' @
    user-message (word "There are too many cars for the amount of "
+ k7 o7 |- U* G* w                       "road.  Either increase the amount of roads "
6 ^* V# n6 S6 f( ~0 t) o7 r) Y                       "by increasing the GRID-SIZE-X or "; j: ^8 s' ^9 [3 j
                       "GRID-SIZE-Y sliders, or decrease the "# d9 }. z4 D6 I& H( s
                       "number of cars by lowering the NUMBER slider.\n") O5 X* E( |: K: K
                       "The setup has stopped.")& O) b. }  ?8 y5 H1 S
    stop: P; |7 R0 q. I3 T8 y# D3 X
  ]' A5 S6 [( F) u1 m6 x$ V

2 P. _! ^8 u" F; o# J  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ ~0 Z9 j4 X% Q/ d: `( ], S  crt num-cars1 L/ R) d' Y3 k: p5 g1 p
  [" f* h$ X  V4 F( S
    setup-cars
2 d/ B+ v4 F" f* |    set-car-color
2 z! {2 K3 D3 w    record-data
! U+ B6 R4 _1 f! v- }4 I0 j0 R% K  ]/ u. b% p* x7 a+ u- ^$ l8 T
1 h9 N2 D6 b  R3 W
  ;; give the turtles an initial speed
6 U1 i% p# K& n. d$ ?' S  ask turtles [ set-car-speed ]% W" I( U5 c( l. a8 G- \
) |% M$ C6 Y/ A- j* F
  reset-ticks  O$ ~  N. e, q) V; s# c. o' X
end
! T, x$ j9 m6 O1 U7 d( |" G( d$ r+ _, ?2 C
;; Initialize the global variables to appropriate values
& u& V$ N$ S5 i2 M% H+ B1 b0 y+ D' Jto setup-globals
, ?% U1 T  c% [* U  set current-light nobody ;; just for now, since there are no lights yet0 E3 {9 _/ F8 Z7 B) D2 Q
  set phase 0+ s. L& O2 c% b$ [# \2 @
  set num-cars-stopped 0
: Q) k9 `% P9 w, j  set grid-x-inc world-width / grid-size-x5 C* c, [2 M9 @4 m, ]2 C
  set grid-y-inc world-height / grid-size-y) ]. k& ~1 b9 U& D

7 h) t" ?) w; {1 W. F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
) ]! K8 @, \' Q$ \4 F/ m  set acceleration 0.099
5 r9 _: `2 c: f8 o' z6 {  xend
; h+ m/ F& a7 E9 y% w8 k" y# \- W. w0 |% A' Y, _( q* _
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 C* L- t1 x" j3 l+ A
;; and initialize the traffic lights to one setting% }6 M8 v' i" v
to setup-patches' x5 k' [5 m1 j& {- A4 Q
  ;; initialize the patch-owned variables and color the patches to a base-color* x; E9 M2 g. H' @4 H* X
  ask patches
3 ^* D0 R! f8 G$ b  [
4 w' w6 J) E8 A' N    set intersection? false0 B7 i# J6 D7 `$ G* k
    set auto? false
5 E; I4 q/ U5 P3 c# L    set green-light-up? true
2 M* |4 H& S: n4 e& q( Z    set my-row -1/ n3 [) U6 q( `7 k% J
    set my-column -1
1 U6 Y' ?7 t4 ^7 ]! _7 ?; w0 T    set my-phase -1) F3 l: @, W: i
    set pcolor brown + 3
2 w! U$ d% c+ ]! R0 x  ]
0 Z0 x* N. g/ O( v3 I8 K
9 |; k3 p7 Q4 a  ;; initialize the global variables that hold patch agentsets0 h" O) {7 [8 T: p: Y" V2 `  e
  set roads patches with
& B/ H6 t0 R8 l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, H, P# O$ K( z. b, J2 K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 d) X' `+ J( K5 K9 y! x/ M8 o# m  set intersections roads with1 N* q$ R# z: g5 @/ q# g
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and9 B+ S; T2 W  f0 h& ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. U7 w1 W$ l! o6 X
* a5 g; `9 c# ]+ [: y( k' U6 U' K
  ask roads [ set pcolor white ]
& r+ S! f& s" {0 r: C' ]5 \    setup-intersections" X# _  E) i7 U6 h9 g
end1 B, F$ h! @% {
其中定义道路的句子,如下所示,是什么意思啊?
8 [: l2 j' ?/ G0 k1 I set roads patches with
, A4 R7 [! ~6 \: b3 I& c5 S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# }8 {2 y0 s8 T' b8 f' g2 d: e    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 s1 Q) K' a9 M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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