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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。
; M; n" \. m7 K$ Anetlogo自带的social science--traffic grid这一例子当中,- c: g" \/ d& d; ^, @7 s* @3 s& J
globals+ x) [+ R3 E  y& f* @
[% Z, m2 F; }- a! y1 y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction3 a  A# i4 d" x4 ^9 g( M7 ]" N
  grid-y-inc               ;; the amount of patches in between two roads in the y direction3 u1 R" i  e! R& @
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& m0 j8 k* J( E' }
                           ;; it is to accelerate or decelerate0 ^" {; P$ r9 ?# A) c
  phase                    ;; keeps track of the phase
6 X1 j  ]" N' m  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure* ?3 T- D  |8 J3 |- Q
  current-light            ;; the currently selected light
; U1 ?8 g% o/ [; {7 F
; Z# s* n3 J1 v* ^  ;; patch agentsets
" L! H$ z) |! F) N+ J  intersections ;; agentset containing the patches that are intersections$ k& V& T) {+ P5 M1 c+ O. I9 K5 |% p- k
  roads         ;; agentset containing the patches that are roads
: }' I6 S$ S3 J1 k( T, R  R1 ]# H3 D]
% T8 i: q* k) E2 N! f; x* x, f% Y
turtles-own9 [! ]* ^/ M- T, W4 W4 k+ h. F
[
0 L- E( _( k. y/ P/ k  speed     ;; the speed of the turtle* |7 R0 B  c# g! k  M& G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
6 b2 b2 X- C6 `! c5 n  wait-time ;; the amount of time since the last time a turtle has moved
( r4 L# U: n7 K$ ?" I3 B]7 n& x' O; \- [0 k

' y0 R5 m1 \+ N" {8 B* M* [patches-own0 A8 f: F1 A; d
[
5 M5 N/ T0 F3 e, r* J2 t  intersection?   ;; true if the patch is at the intersection of two roads
/ n% q( U# g+ w+ Z* v6 P5 D4 g: ?  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 l( N4 @" P( ?7 P& z5 P! z
                  ;; false for a non-intersection patches.. _- |' P. F, A
  my-row          ;; the row of the intersection counting from the upper left corner of the  M1 {% |2 m5 l
                  ;; world.  -1 for non-intersection patches.( ]2 g- v: _7 ^+ M0 {
  my-column       ;; the column of the intersection counting from the upper left corner of the
; q9 n* t, g6 C3 Q% }: v                  ;; world.  -1 for non-intersection patches.
+ F7 H# f# K& Y  ~! T; }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 P# q) L+ T: b- G5 q
  auto?           ;; whether or not this intersection will switch automatically.0 ]) X9 C2 Z( J& I; R
                  ;; false for non-intersection patches." o, j1 P1 P  }& h7 g
]
2 d0 m* f5 x& a; M5 m* V: v; s7 {# j) I5 m6 ?
4 ]3 T2 K( J! W9 e$ a
;;;;;;;;;;;;;;;;;;;;;;" V$ ]7 F  T" y6 |; C9 d
;; Setup Procedures ;;6 t* N  J+ ?0 A# l. J3 |( C: u
;;;;;;;;;;;;;;;;;;;;;;, C( b0 }4 P  v4 i( Q. j

- I9 J7 h& O: S2 ~, E0 V;; Initialize the display by giving the global and patch variables initial values.
( n, r* d  z9 C. G;; Create num-cars of turtles if there are enough road patches for one turtle to
6 @, Z& o" E& n8 A& q;; be created per road patch. Set up the plots.
& z# W- X( n% |/ T  o4 J( T2 Xto setup
3 Z9 [7 M! |+ N4 N  ca
' B+ u+ s5 _# D1 V  setup-globals* j, N3 l, T# r

) t+ q9 A% W: _" E! n8 u  ;; First we ask the patches to draw themselves and set up a few variables
1 C9 N% x# T3 v1 b0 L7 t  setup-patches5 l% Z6 `4 T3 w! J9 O
  make-current one-of intersections7 }! V$ d( ~6 W# K( I
  label-current$ T; u( v) {( I$ X9 h  i
3 a1 v4 c8 H9 H7 _! u& m! ^
  set-default-shape turtles "car"
: I% \* p0 H. |
4 ^2 _/ Y2 D  n5 ?7 W  if (num-cars > count roads)# A& ]' m: N% x' H* X) r) X
  [6 Q2 s% r  ?9 ?! W( `4 i
    user-message (word "There are too many cars for the amount of "
: f2 X) O. g" ^2 n2 E+ e. ]                       "road.  Either increase the amount of roads "7 \% B1 T( x0 a. ?3 l/ E3 u
                       "by increasing the GRID-SIZE-X or "- j; k, h+ `  j% u4 [3 Z5 j* {
                       "GRID-SIZE-Y sliders, or decrease the "
) s! P  W) G1 w0 O6 A                       "number of cars by lowering the NUMBER slider.\n"# B, F8 S4 ?6 y( `) L
                       "The setup has stopped.")
6 X& `$ R( }, Q2 D) v' X& |    stop; e1 j; b" k- J
  ]* b# ?- \2 s+ J( n2 H
" v6 N: U5 m; v+ i
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color  {. }" T0 I  K8 Q# I2 [9 b
  crt num-cars
; S$ y4 z& t; M  [+ E. z' \4 @( q& g6 `7 C9 V( f
    setup-cars! W7 M' x3 D3 P3 n. x9 B  U! N
    set-car-color
  Z! H7 m# Q$ z: v& J1 q/ [    record-data$ K7 M8 C' ^4 O6 X/ p5 ?
  ]
! D9 @0 h& d7 w) H- l  f, A
" _9 ]% f+ k8 l0 X1 E1 ]  ;; give the turtles an initial speed) e% g9 X3 ~: M# c. Z
  ask turtles [ set-car-speed ]
0 S  E% Q. G0 x8 \! q! |7 F2 k0 R9 Y0 z9 A! q# v4 b
  reset-ticks
7 g! p) d" x' E8 _$ Q8 tend
+ z" ^: E/ o. f/ ?$ I- i
& Y" z0 A9 Q+ R" H) D;; Initialize the global variables to appropriate values" ]' k( Y8 e: N9 ^1 _' I1 G& l
to setup-globals# R' {( D8 {; L3 v2 S$ E- M
  set current-light nobody ;; just for now, since there are no lights yet; v  H+ T8 B3 L4 n! Y; {
  set phase 0
1 B) i: n9 r) I* s+ y  set num-cars-stopped 0
; Q$ ^9 i$ v; x7 a$ Z  set grid-x-inc world-width / grid-size-x
2 V% y# r7 Y( j  set grid-y-inc world-height / grid-size-y
/ ^% e8 q3 |' j4 Z0 R4 P- Y6 B
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary0 f6 \% O6 x; x( X* J
  set acceleration 0.099: N7 `7 S" O- o; w( N
end/ s( u* j) z0 S3 x9 V( P

# F, s6 z8 o3 Q4 l/ o;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% k# ]  t& _4 q( d3 J;; and initialize the traffic lights to one setting
4 b. R. ?7 |4 e- Lto setup-patches7 ]% L+ W0 J( G2 k! L2 |) {
  ;; initialize the patch-owned variables and color the patches to a base-color. L; B$ Q6 p2 p
  ask patches' ?3 S+ }- a7 D: k
  [0 f+ O8 m/ N2 B7 b) _& k  e
    set intersection? false
# I# H+ p$ w4 s! y  Q/ K. v7 P' }7 T    set auto? false. k2 P2 e5 p& t, m
    set green-light-up? true
! d. ~! g( q2 t    set my-row -1
7 @0 {6 o+ D( E    set my-column -18 l& k" s1 T9 R: \, k+ e" X
    set my-phase -1
- T% H. {; x% x% }2 \+ i    set pcolor brown + 3
' c+ c8 W* ~! ?7 L  ]
" B5 R& T% A, P$ f. n4 Y& X; G3 ^9 u! R
  ;; initialize the global variables that hold patch agentsets
' b# p* F  w+ Z5 y  set roads patches with
- H% _9 z$ ]8 B/ b: S; x2 o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ f& J8 k( R; Y- B3 d    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, x" h0 t2 L' e1 I) [8 _  set intersections roads with& b/ Z  |6 o0 @2 s
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
) W9 _1 e3 J' n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
( p) H9 g$ D! l; p  {$ d# E
3 b  R/ m: u8 `5 x  ask roads [ set pcolor white ]
: z8 u0 U4 j- D0 ]+ f/ t    setup-intersections2 x4 _6 U! B# \
end
( N4 P8 U) y6 O  W  K其中定义道路的句子,如下所示,是什么意思啊?: X; a( }& j5 [9 e9 m+ b& Z* a/ }8 W
set roads patches with
  E0 ]; V: x. M( C* R( E    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 P( |, C( L% s, L8 o8 \" b    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' l/ z1 {5 C( X! A* A# n
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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