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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。  L3 Y" [6 T" H( ]8 P
netlogo自带的social science--traffic grid这一例子当中,. b- i, m# u" W3 Y; i
globals% O6 p6 \5 b" m. R
[: e/ \1 m# Q3 {& w
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 ?) p- a* ?& G" N
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 i& O: G* G6 \3 y
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& O, U9 E# Y, y7 T8 a
                           ;; it is to accelerate or decelerate
" k' f) o3 v: S2 x  phase                    ;; keeps track of the phase, V, I% L3 p: C
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure, I- T% {# T% G, K/ D0 S( G
  current-light            ;; the currently selected light8 I5 m2 Z9 u4 S5 Y

* n' ?  c8 F3 V$ o2 P# n5 ^9 ~" z  ;; patch agentsets
1 F: V# V% }6 C( b5 k  intersections ;; agentset containing the patches that are intersections
6 c- Z1 u+ c9 X0 j! [  x  roads         ;; agentset containing the patches that are roads! M9 H9 ~1 S9 A: r' Z5 |) e
]
) r# N) p  F9 u) Z' R8 F( E' v/ t: j: r5 q9 X
turtles-own
9 ^# B6 J" Z. P, V; b  V! ]! ~[8 ]9 X7 s# V5 K/ F6 _7 \. `
  speed     ;; the speed of the turtle) @) \' l4 L  q( D. d1 x
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* V% Q" A! y) V* c  x: m  wait-time ;; the amount of time since the last time a turtle has moved
" y1 N% {7 f0 m: v]
+ L' X3 A+ f% B4 f+ a- K- t  q  y% l, [/ w0 h
patches-own0 Y7 [% E- ]# w! W& d- A! [, c
[7 F  u9 c. J% `4 w8 ~
  intersection?   ;; true if the patch is at the intersection of two roads
! T& F5 W# C+ S) K' J+ m0 z) T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. w/ M+ `- O3 R1 j                  ;; false for a non-intersection patches.
+ a: o! u$ m- |  my-row          ;; the row of the intersection counting from the upper left corner of the
2 D2 g# R3 Z9 x* N+ v                  ;; world.  -1 for non-intersection patches.# O! h7 F' m9 S& q* _7 S# s1 X
  my-column       ;; the column of the intersection counting from the upper left corner of the
% h  P2 \6 V, g( s2 a                  ;; world.  -1 for non-intersection patches.7 X. R& T, ~* P) T7 c
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.' i7 v/ J& }$ V9 P8 g
  auto?           ;; whether or not this intersection will switch automatically.) _/ |6 U' Z% A! }+ K8 n1 {/ R
                  ;; false for non-intersection patches.9 Q. H% _/ E8 J" h! Q* z; v) {
]" C: G  g, ~1 O: A* Z
! u9 L+ M; s7 P5 c" Q

8 c+ \- ~% ~$ C8 k/ U;;;;;;;;;;;;;;;;;;;;;;
4 w: ?7 S. ~. Y;; Setup Procedures ;;
- W5 w$ g& E, f4 V# m. E* e) Q/ Q;;;;;;;;;;;;;;;;;;;;;;- q) D. o1 A- C( s4 `
& j4 D7 d2 M. `" V7 t8 q
;; Initialize the display by giving the global and patch variables initial values.
8 s/ `, ?) N/ b1 p3 M7 e;; Create num-cars of turtles if there are enough road patches for one turtle to
* s2 K2 P" L* F; W0 g* u;; be created per road patch. Set up the plots." K3 r$ ]1 B) n
to setup% p4 r# r9 k$ f' l
  ca& ]+ z' ]0 d8 s/ }; z  K6 r5 i
  setup-globals
' A+ J. G  G, f4 k; v& D# ~* _* D! r% l1 e; z) o7 N
  ;; First we ask the patches to draw themselves and set up a few variables. f5 C- s, Q" U9 N: P- L9 N
  setup-patches6 o& a/ ~4 b2 _
  make-current one-of intersections
+ ~- K3 ~% t8 \$ n0 @- L  label-current) Q" Y9 r% O4 w5 A2 H* k
! U2 [/ h) \$ N  s8 V0 e
  set-default-shape turtles "car"/ L' E2 \$ R( \) g4 b$ v4 c; ]

1 W* k. D* }9 m$ \7 W  if (num-cars > count roads)6 |- J' h9 K1 A; i" b3 [( T' @
  [! j% l' ^+ q0 C
    user-message (word "There are too many cars for the amount of "
" Z# `: [/ c0 M+ v7 L                       "road.  Either increase the amount of roads "
0 {# j5 P1 o* ~                       "by increasing the GRID-SIZE-X or "
9 v) E) c. `% M2 y, O1 {                       "GRID-SIZE-Y sliders, or decrease the ") i8 e: L& g' U4 Z0 g7 N
                       "number of cars by lowering the NUMBER slider.\n"
. L' f- [0 t2 E& R. t: ?, G; g                       "The setup has stopped.")
3 q, ?0 M7 J& e2 V4 B' R2 c    stop
! H6 L$ Z1 n6 _0 ^7 }  ]+ D' N1 z% V: n, \
. o3 T+ V6 B+ |1 P
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
6 g9 j  i6 o- O7 X  crt num-cars
/ Y7 E$ h- p* j. {! e2 [  [$ A. m1 s6 e" U' l8 C- o4 j
    setup-cars! w" K) L( V9 V/ m% W/ p# Q; O
    set-car-color
4 l6 c& U  }, C    record-data
$ k# ~% B% A& v: |5 r. q: v  ]' V! i; r- ]( C7 a+ U

1 `- `: x& I/ q+ H/ ?( l2 D  ;; give the turtles an initial speed# X/ A# l. t1 ]# |
  ask turtles [ set-car-speed ]4 m- U: V2 M, W. |, a3 X8 P

* R% E7 S" J. C  reset-ticks
0 A5 t7 R9 h# b+ ~, k+ Fend
# Z* v2 K) t4 h* d% O
& j& Q# l! z2 z! K; @;; Initialize the global variables to appropriate values
* K4 b1 W: u; i8 f+ dto setup-globals) w2 d9 n6 `/ t5 [
  set current-light nobody ;; just for now, since there are no lights yet$ p; J  W4 Z/ }2 ?# ^6 q
  set phase 0
& {  K( a, q& y% C9 ^: \" T  set num-cars-stopped 05 `% _2 E" o; `3 H
  set grid-x-inc world-width / grid-size-x, U% `8 [5 B2 V- D
  set grid-y-inc world-height / grid-size-y4 {$ Y! o8 u' X
! y) r! K' H9 g% T1 ]/ ~9 V
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
9 g, f, b$ M+ j8 _, w  set acceleration 0.099& w' p! c" v5 y4 C# u0 Z9 Q
end
# N+ a5 p5 @3 O7 O8 N5 k, q
% O; B1 s  Z+ A. x0 @; |% ?4 A, Q$ R;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  r' m* \1 k5 W. m;; and initialize the traffic lights to one setting
0 i7 \% ~9 w* a5 `( ^. e8 Hto setup-patches) i: p! v: c) ^/ h
  ;; initialize the patch-owned variables and color the patches to a base-color* C' k' e  z- ?  k
  ask patches
4 @( G& C) N0 ?9 O( q3 @  [/ D" M- T+ H8 m7 o" L9 h" h4 F. R
    set intersection? false- [% w+ n7 ^( q
    set auto? false
7 {1 C; P$ O  I$ m1 k( q  U    set green-light-up? true
4 |- `7 J  r9 S; Q, j    set my-row -11 b5 w2 e+ p* p. C+ J% s& q
    set my-column -19 w& |2 y, b+ v
    set my-phase -1
9 e' A4 p& O% l6 K" z# l    set pcolor brown + 3
' |% ]7 G, y! i1 q! Q; O  ]. g8 n. x: d- n5 h

! i; H" k& ?# n% `9 w! B! y* b) A  ;; initialize the global variables that hold patch agentsets; a" E; B, |4 j! Q$ O
  set roads patches with
* g, O3 H% r8 B; D) K    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! t# c" v; {& L$ \, u
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 ~$ E7 c- g/ w* @2 M) |; V' |- i8 M
  set intersections roads with4 J7 B9 @" P$ H. `% v! Y
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 G* G" N' v+ N' r1 @$ N6 Y* s    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( Z: J1 P  H" x1 i5 ~
8 [' K0 W! @& o- V  ask roads [ set pcolor white ]
; e. y+ K9 e, O" ]    setup-intersections7 M' ?, i; J2 g: C  f$ Z
end3 e0 f- m) V, F/ G/ U# I
其中定义道路的句子,如下所示,是什么意思啊?
3 h) G, h% }) h+ e& V set roads patches with9 |+ ^( m; T, g+ {$ o' T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. H# B+ ~% X6 z: b$ ^% d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 G9 T1 f: u/ ]
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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