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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。) K9 z' t; f# U6 X7 g3 Z3 ?* T
netlogo自带的social science--traffic grid这一例子当中,
# m% u, ]2 l0 c: I1 z2 M& mglobals. b$ y3 a. B1 `5 W( `6 f7 X
[( t+ M4 I, q$ H- O3 k) d
  grid-x-inc               ;; the amount of patches in between two roads in the x direction" a- a+ W$ P: E6 w+ ~; D7 F
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) X) e& e0 f3 ^5 @. f  acceleration             ;; the constant that controls how much a car speeds up or slows down by if( I/ q# C( y% b- i- V1 D" {
                           ;; it is to accelerate or decelerate) N+ E3 Y; u% @$ ~; ]) n' D
  phase                    ;; keeps track of the phase' t6 r7 k/ t% |: @7 W
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 w/ p/ s+ m. r  current-light            ;; the currently selected light
. I) @: p9 l$ o2 N, W8 V, L- i8 C2 ]; c' X0 f5 W3 i: g5 H% D
  ;; patch agentsets* N+ r9 X  F6 R, ?7 n9 @
  intersections ;; agentset containing the patches that are intersections' W" e1 c% G0 z
  roads         ;; agentset containing the patches that are roads7 _3 a4 a5 J# O- ?/ c/ n
]
, q, M0 G. E9 K" [' S# X# {3 ]& A! O" R% U- Z' P2 V) s
turtles-own
; x: G. A. T& d- k( ?[  E, Y8 \+ K% b3 |
  speed     ;; the speed of the turtle0 x4 d; C! {7 A9 d' e
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right+ X; s6 b9 g' X& i
  wait-time ;; the amount of time since the last time a turtle has moved
6 {/ d! i, O. O- M: l) ^% Q]
8 H- t, E3 u* P6 i0 a6 W" I$ A
" r& C+ m0 d5 {$ A. T& Upatches-own
# ~+ V8 @: \  b7 `[7 G2 I  f! [3 b- H: _8 z' d
  intersection?   ;; true if the patch is at the intersection of two roads0 R; @" B: o8 f" C: x" S, r/ V
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.8 d$ s( U8 A* I4 U: s6 b
                  ;; false for a non-intersection patches.' N' |5 x- Y4 S- G/ R$ Y, A+ v  c9 b6 f
  my-row          ;; the row of the intersection counting from the upper left corner of the8 a* I% A  u- H& p+ m! Y- P) `
                  ;; world.  -1 for non-intersection patches.
4 K/ E! z! d8 b2 F  my-column       ;; the column of the intersection counting from the upper left corner of the
- A2 G9 {" P: E                  ;; world.  -1 for non-intersection patches.
' L1 S2 L4 e4 j, @  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 Q: A4 I# A5 O$ A% l7 R+ y
  auto?           ;; whether or not this intersection will switch automatically.
4 J$ r& k; `. e, {# Y" ?                  ;; false for non-intersection patches.
1 Q: T# w: L# E6 h5 m]' Q' t+ n7 |0 C$ R3 A- u

4 l) T5 k# j- z- `# P! n
7 q9 ?8 o) l6 F' H;;;;;;;;;;;;;;;;;;;;;;
2 z( [6 L+ a% `! x( G;; Setup Procedures ;;4 a  M' c- w. D
;;;;;;;;;;;;;;;;;;;;;;9 u% U/ ]6 t. ]+ q2 d" \

1 V. a! H( W; X3 t! |; F;; Initialize the display by giving the global and patch variables initial values.
: F5 ~& Q) P! b+ z+ [  t;; Create num-cars of turtles if there are enough road patches for one turtle to
) P7 q; k5 Y- ?( U;; be created per road patch. Set up the plots.' _: f3 h- U, m
to setup. x4 L# a! i7 b1 L4 L
  ca
) L! p6 f6 l- h  setup-globals& I8 l# H. a# \, L9 b8 f  _0 @: \* ^

: r) A. B6 D/ q$ Y$ v1 h  ;; First we ask the patches to draw themselves and set up a few variables
9 y/ F$ n2 P! u) g  setup-patches/ W) ^! q$ v8 C
  make-current one-of intersections
8 l4 p& \3 A+ G) l- |0 m  label-current5 N+ ~% P5 O9 L0 X/ Q/ g2 U% |, {

+ [) K0 G1 }% f$ n4 H  set-default-shape turtles "car"+ c6 c- z0 K+ \6 W
$ ?$ o9 Q" o4 ^
  if (num-cars > count roads)
7 w- W8 K/ p' u7 K* Q( ~) Z" N. O& q  [4 [! v3 e) Z( \
    user-message (word "There are too many cars for the amount of "& {. K2 J) ~' W3 Q$ r
                       "road.  Either increase the amount of roads ") q" u) }0 F2 z0 L' x
                       "by increasing the GRID-SIZE-X or "/ D$ l& A- e5 t0 `
                       "GRID-SIZE-Y sliders, or decrease the "
/ Q7 {+ c4 w. @$ _/ C# b                       "number of cars by lowering the NUMBER slider.\n"
; X9 K' ?4 l" L. M0 ], w3 w                       "The setup has stopped.")
) ?- |) X2 j- _8 U    stop
6 x# p, u2 U- h  ]
: p( j( r' Q2 X! C3 I# g4 o2 G/ u2 t0 W; m; S1 r/ l1 \! p
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color4 s3 F" s. y: C
  crt num-cars7 f1 s0 f1 q+ K
  [
- c8 J! m7 D8 U, m    setup-cars* v6 B  D7 v$ l1 Z
    set-car-color# P2 b1 W" g( N0 u9 y3 V/ a
    record-data
+ ]$ W) |* B% F5 Q  ]
+ e' T+ R) A+ u; D: Y" l3 V
- O8 K- X5 [( ]$ s6 D# u& ^  E  ;; give the turtles an initial speed5 B4 q& d3 x/ |& ~. [$ e1 [
  ask turtles [ set-car-speed ]
+ J! k9 \: ~% q4 {8 j/ [9 Q9 `( A+ ?2 a
  reset-ticks
% n* \2 l8 |8 R+ V* ?0 Yend
) x) w6 v2 G( p& w; t
6 r( V# b$ y$ [0 p' |& n;; Initialize the global variables to appropriate values
9 j5 ?: w& k7 q+ S6 ~- Eto setup-globals
, y: D" }( X- f  P6 e3 O9 P  set current-light nobody ;; just for now, since there are no lights yet# U, x7 i6 q. c/ C5 L/ S
  set phase 0
* q5 @6 X) t' N( w! N8 S  set num-cars-stopped 0
. D! Z* T% P& Z  set grid-x-inc world-width / grid-size-x
* z% r$ J2 P# K5 L+ l3 w  set grid-y-inc world-height / grid-size-y9 {" W8 I& q, z& L: |8 Q

9 M/ w/ v7 a: P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
1 R3 W/ ^7 l+ N' ~" H" j6 Z  set acceleration 0.099
+ S, i- `& P1 E! J$ z& fend, x" U/ T1 S% D) M0 F. E
4 w& J( |. T+ [& _. z* k- X
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,& h7 p( I6 z& V* v% [4 m% ^) ^' a
;; and initialize the traffic lights to one setting" @3 D! S: G4 `7 k& {  d* J
to setup-patches
0 N* o* |, P/ e1 T  D  ;; initialize the patch-owned variables and color the patches to a base-color1 m! }8 x- u/ j% H
  ask patches: y' C3 c5 }. K  n( K
  [8 z" v, d( p  V  g/ E4 c& [
    set intersection? false$ w( h. {3 G" w( \+ Y
    set auto? false. Y/ @) s8 }4 e- g
    set green-light-up? true
$ Q; J+ a* d$ p1 B) z7 k) ]    set my-row -1
! X+ M3 @; C5 K$ G5 ^    set my-column -16 y) H0 S! p/ v- h8 \
    set my-phase -1$ n; v# V, C( |5 K+ e7 B& E# q
    set pcolor brown + 3
7 u0 N; g5 }5 C  ]  S3 W  G. d/ u! i5 T. r9 F- ]

" z2 x8 k- ~9 j% u; m$ Z5 A  ;; initialize the global variables that hold patch agentsets* X6 y3 E9 I4 o; I& u8 n" G: q' R
  set roads patches with1 ]7 V- M- f/ l) K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* U' m" x. S9 X
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( T% D2 F* q& Y  H5 |4 z1 H
  set intersections roads with
4 E4 f, B- U/ r  o    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and( g& ^* c% X! I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. Z6 u$ L( b& F4 Z$ e0 L7 m; w' o
6 u  v( W3 W  Y* L( x
  ask roads [ set pcolor white ]
7 k. b, h/ c( G1 ]3 v  v    setup-intersections
1 E: o* x8 l$ {# a& Eend" x( X  E7 i  n6 [) `  C( q
其中定义道路的句子,如下所示,是什么意思啊?7 A4 }6 [/ S& @+ s
set roads patches with
! F: o3 k) _3 U" a0 N4 S& w4 H# n, I    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ J1 W8 ]- X6 s1 I0 R" \. d% o" |* A) \
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 ]  E* I- f# G" o# ^" V' 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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