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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。
" j: t+ H3 ~4 g! V$ a+ ynetlogo自带的social science--traffic grid这一例子当中,  A( V$ j7 L5 P( A, ?8 c+ e& ]
globals
2 d5 t% r% l+ o4 a  Y6 `, X[
8 R$ P& l: s5 W! k1 J  grid-x-inc               ;; the amount of patches in between two roads in the x direction
9 [' N6 S- m( H  grid-y-inc               ;; the amount of patches in between two roads in the y direction/ J0 {3 b9 {1 I2 W, T6 _  R
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
, h. f$ v% M: n2 _0 }) S' Z                           ;; it is to accelerate or decelerate
9 C6 c! l$ M& t! H, C3 Z- b1 @  phase                    ;; keeps track of the phase
: i/ F# u" _) C1 b9 [% d. L  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
# n" R/ e+ t' N8 ^  current-light            ;; the currently selected light% L3 ?1 N% i* j, n% Q8 Y* E
1 J3 O0 d/ Y% W; p& y, b) N6 M
  ;; patch agentsets
+ {1 D& ~8 A+ v  intersections ;; agentset containing the patches that are intersections
' [7 B, v# E& ?' ~  ]# v4 H1 c  roads         ;; agentset containing the patches that are roads. Q, o1 V, _, {* W# ]; a
]8 D% v# K' [8 }, m! T8 }- W
* P) V) ?' f9 P  w
turtles-own7 m) F* H/ K! d: O; S
[" F) }5 V$ R4 |8 Z8 w" d
  speed     ;; the speed of the turtle, H% v. E1 I: F7 A6 M
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( H" [9 y' d0 W1 _+ f  wait-time ;; the amount of time since the last time a turtle has moved" i% {7 i3 \3 \( G$ {
]! `$ K: @5 |9 `4 s
) u7 i6 _" N/ t/ E5 ]4 t
patches-own3 ]9 q" F* m( v- m
[  m9 U6 T  e6 ^' K
  intersection?   ;; true if the patch is at the intersection of two roads- c# |$ Z- w; O2 t
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( h' ~! ], J2 }8 g                  ;; false for a non-intersection patches.
' g' L' J8 N7 s+ M* F/ O  my-row          ;; the row of the intersection counting from the upper left corner of the- Z/ ]0 B1 T5 ~  H
                  ;; world.  -1 for non-intersection patches.* Z5 }/ b- r1 Z! n" w4 p# u
  my-column       ;; the column of the intersection counting from the upper left corner of the
: W/ R  J" ^) G) p: I5 E$ K                  ;; world.  -1 for non-intersection patches.) i! ]$ c$ |% C4 m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
3 \+ d0 m) T- ]  x% [0 U% t  auto?           ;; whether or not this intersection will switch automatically.# i) }8 O" m9 z% H
                  ;; false for non-intersection patches.& F7 g+ A+ [/ X% G
]$ i' T6 X; h6 q, }7 l! w

% [; H) v9 ~( a* E+ \: h" m7 s$ q1 O( e: U/ o1 P; Q0 t' v
;;;;;;;;;;;;;;;;;;;;;;
0 S1 T: [1 c* S2 z" N' e$ w;; Setup Procedures ;;
$ ^2 {- B. x2 F  u/ {;;;;;;;;;;;;;;;;;;;;;;
! l6 J! ]6 y$ P: H! Y* w& i+ P. t# P7 f7 ~+ A4 b: z; H) W
;; Initialize the display by giving the global and patch variables initial values.  q7 a+ S& W! a0 M% r; H
;; Create num-cars of turtles if there are enough road patches for one turtle to
1 u6 Y/ t. b1 S$ {% {) ~;; be created per road patch. Set up the plots.
  j, q, a, X3 Nto setup  t; c2 y( X" b* M
  ca
9 Z7 J' P1 P1 \2 |/ c6 o  setup-globals' {8 j3 Y! ^  A" s8 A8 f

& b' i6 m: S+ S. ~$ v4 b" G! E  ;; First we ask the patches to draw themselves and set up a few variables
* S7 S& O0 a+ p  E5 v  setup-patches
; K' ~1 G0 Y4 e, v7 t9 K* i  make-current one-of intersections0 x% `8 K9 y7 \# l4 y
  label-current( Z5 m9 |8 {' V+ f8 K6 l
8 @; C! ~6 R  Y- `# e7 b( V9 z
  set-default-shape turtles "car"; S" H- A7 I3 G' x( b; Y

7 F( d0 p& e3 |9 H# i" M0 N  if (num-cars > count roads)
6 Y0 G+ w+ n) `1 X- J  [/ m5 E6 i+ Y( A
    user-message (word "There are too many cars for the amount of ") ~/ W/ V. C  F6 L$ B! A+ k9 m
                       "road.  Either increase the amount of roads "
. ~; e$ k6 {7 y) z. k* p                       "by increasing the GRID-SIZE-X or "& T0 m. T/ z* N
                       "GRID-SIZE-Y sliders, or decrease the "" E$ ?: M3 \% ^/ L2 {4 H2 O; v
                       "number of cars by lowering the NUMBER slider.\n"  ~  U3 D+ ]1 e6 R7 p/ O$ V0 q
                       "The setup has stopped.")
& C* e6 Q- F1 e% M$ n; ~    stop
/ H4 I$ U3 s; s% Z* E  ]
" g3 U* a$ o3 I8 N6 r1 R. W4 h
: P' K9 M5 ]3 p+ m  v' J  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) o' M  S* A- h8 P# O& D  crt num-cars
' S! e& d! T' p9 m' i4 i  [& m- h; `; J/ D1 W9 F
    setup-cars
6 r5 B7 N- w4 L% h5 f# h    set-car-color. A0 Q: k- r5 C$ _( F7 j7 Z( d
    record-data
) ]4 A6 b& d  I* i* {  ]
+ A/ ?% G: n% V  \1 l$ e" c( l  g% t4 V- b: K- z
  ;; give the turtles an initial speed
) w2 J* k# O9 \8 }, z+ p7 K  ask turtles [ set-car-speed ]' B6 L* \6 @2 I4 E7 Q) f

) F. x) k' g& G+ U  reset-ticks
2 X' ?5 t3 v* @3 B! o6 ?) t- Fend9 D+ H( U0 W2 p0 e; z

* i! q- k8 w  ?' i. o;; Initialize the global variables to appropriate values
  Z+ ^* X% i6 t: O' K8 W2 h9 o& _2 yto setup-globals
' W2 {# C( Y, g! |0 H8 d' B  set current-light nobody ;; just for now, since there are no lights yet
" D% _! H" V: K8 O+ z7 v  set phase 0
! a0 F* u1 @4 ]8 ?8 |! q  set num-cars-stopped 03 K. b- V7 }) {5 m" }% I
  set grid-x-inc world-width / grid-size-x
7 _! B9 l. {* a9 w  set grid-y-inc world-height / grid-size-y
8 S! m# T7 K, ^7 g  Z/ {2 c; A
- M, G, {7 I+ A0 E+ ^8 w  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary& d- m# y6 T5 W* S+ r  P
  set acceleration 0.099& k! O+ X5 I" K' C
end8 R6 T% V; t' ]/ ?% {$ o

3 E' f! n& z( z/ j- q) d;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 Q& \2 ~: _8 _# f7 w1 d  p;; and initialize the traffic lights to one setting! x0 x$ u: Y. J- u9 {
to setup-patches6 h; {& F9 V( T. a1 e7 [8 `
  ;; initialize the patch-owned variables and color the patches to a base-color
4 C# R% y& t* _: w* l: r2 [  ask patches/ [& \& W; _3 ]5 g2 W( P
  [
& H4 u/ Z5 M* P$ z. r2 s( k$ ]+ [    set intersection? false* G( @0 L& A  i5 L& |1 F
    set auto? false
/ a3 ?6 T0 e& e/ R    set green-light-up? true6 z4 N% U, h" P% a+ |$ ]
    set my-row -1
" Z* E, D3 V; x' U' @5 e* ~% M  H    set my-column -1
) J; E! k5 S% o# h* X5 G    set my-phase -1; G- a- G1 I* N# f+ |
    set pcolor brown + 3% ~: U/ C; E4 g! ]( X
  ]( \) ?/ ^1 M  g7 {0 w

$ v/ B, j; |0 N# s4 j$ }+ v, Q  ;; initialize the global variables that hold patch agentsets
9 l( ]% e4 r, j. G6 `/ D8 T  set roads patches with- f8 j6 C' \3 y  x1 `* i# ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' G! g& u% {2 _1 W" C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  f# `+ [9 W- S. B9 I6 L9 \) g2 @
  set intersections roads with6 U* v3 D+ B. v0 D/ l: ]* v
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and- p! ]7 t0 H7 v( O9 X1 f- D5 s5 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: J- ?* |, I9 w) e! d  z% k# Z

9 {2 L& }! v( f. v  ask roads [ set pcolor white ]
9 ]2 ^) q4 {' t$ [    setup-intersections
* D& V' a* @( send' r; U8 H: e- _* h3 e4 z
其中定义道路的句子,如下所示,是什么意思啊?
! Y! _. {! |7 s) P- I9 Q: a set roads patches with
& C; j6 `) X, k- n0 H  Y5 T    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' d$ _, ~/ R. x  M
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ r9 a9 X- w4 ^1 P( O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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