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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。7 [& \% ?7 F5 t
netlogo自带的social science--traffic grid这一例子当中,
3 G6 L& H3 k8 g1 _; j- cglobals( k/ h# Z0 Y- k' [& Z% b
[
. d2 }" C% m: F  grid-x-inc               ;; the amount of patches in between two roads in the x direction  n( W1 o! Z* M) G6 T9 m  x! n/ f* y
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 [# ?# W. p  p8 {% `3 ?  acceleration             ;; the constant that controls how much a car speeds up or slows down by if$ w* |0 P: H. K1 G- u
                           ;; it is to accelerate or decelerate! }. b8 W6 L4 g5 x0 o8 W
  phase                    ;; keeps track of the phase" t3 M! g6 ~5 \" B; m+ p3 T
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure" w5 l$ g) M% m1 w* i# N' h- p4 {
  current-light            ;; the currently selected light2 f. I" L, g+ J, B

5 i* q, j8 O' X! B$ g4 N  ;; patch agentsets' L  t2 y$ i6 }) S$ l# C; J
  intersections ;; agentset containing the patches that are intersections& D, @* D+ w; Z' r
  roads         ;; agentset containing the patches that are roads+ `; x* ~2 h1 n
]
% F+ ^+ [% T( `/ `. s5 w' X3 N) o0 _7 J% D( L+ k0 i6 ]
turtles-own
5 b. G2 \' T, j! A1 a0 S[) s. r+ |+ E" R( t0 h5 C
  speed     ;; the speed of the turtle6 D  e$ c2 k; A9 e& L  |0 z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" Q5 K4 Y7 ?7 b% b- ?
  wait-time ;; the amount of time since the last time a turtle has moved1 N. j' g/ v# b- G3 |2 _
]
5 X% f* }( W+ m7 L/ J/ P6 G: a! O
& j, d6 u+ f! `* g1 y  i1 T' \patches-own
8 j: ^" f" C( e6 q& q[7 s' E6 x' B; N. k0 e( ?
  intersection?   ;; true if the patch is at the intersection of two roads7 ]* O3 m% U, B* m0 g
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% X$ C+ n6 C; ^) I5 Z8 |8 G
                  ;; false for a non-intersection patches.4 N. s6 W9 N: J' |7 U1 z  Q, X
  my-row          ;; the row of the intersection counting from the upper left corner of the
$ y- m8 J5 h5 h                  ;; world.  -1 for non-intersection patches.
" [( `) Y4 c/ j0 ~2 x: `  my-column       ;; the column of the intersection counting from the upper left corner of the
- f# A# ]  O& m                  ;; world.  -1 for non-intersection patches.
) H# G" m- g; H7 ^& ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
( t) i5 t' v! `3 d  auto?           ;; whether or not this intersection will switch automatically.
5 l4 Y; d9 D4 r% w' v                  ;; false for non-intersection patches.5 I8 @; ~& w+ u. x+ f
]$ {2 v5 F" r' O6 x$ J# N

, R1 c5 n6 K0 \& a+ X7 k1 R9 m" F3 F& K  F. @
;;;;;;;;;;;;;;;;;;;;;;
* l) j" b0 x/ g) G+ V) U$ W' w- [# m8 S;; Setup Procedures ;;
4 N6 t4 U6 @6 |$ A7 |;;;;;;;;;;;;;;;;;;;;;;
0 }; h) `6 u5 u! v8 t& y, T6 w$ C/ D2 o" \( v8 X8 p
;; Initialize the display by giving the global and patch variables initial values.: m* ]  X' v. q& A% c4 b$ s
;; Create num-cars of turtles if there are enough road patches for one turtle to+ F) r! c- k9 Y" P/ e# F- U
;; be created per road patch. Set up the plots.
$ n/ Z  `$ t: E4 {# I7 y. hto setup
& J- w7 M* Z& i  ca
6 L# J" D2 F2 X( l- d2 n- U7 z; O  setup-globals$ R% }; h  @( I. O

) P6 [/ U) ?* ]6 c7 P9 X9 B  ;; First we ask the patches to draw themselves and set up a few variables
# T/ |! K  k& ]# [  setup-patches4 ^9 ]2 I- C8 b) a' h3 v* t
  make-current one-of intersections
1 z; G* @- c, Q  label-current
& j* Z5 f  I$ R  ]7 U
! e6 G7 s: n' w) m  set-default-shape turtles "car"
8 n  O0 v) w/ L$ f! t; K0 a, N
& ^3 ]  n+ K6 t% j7 q8 t  if (num-cars > count roads)
" }1 b" O% G' M& h. q  [/ u2 t. \4 J$ b0 G" \9 d; {  h
    user-message (word "There are too many cars for the amount of "
7 D+ `2 d( f$ e# d                       "road.  Either increase the amount of roads "
& h" u- Q" d9 D6 R4 ^, W9 j                       "by increasing the GRID-SIZE-X or "
3 s9 v% `# [. V                       "GRID-SIZE-Y sliders, or decrease the "; V9 z! \4 }/ C; }$ V, D
                       "number of cars by lowering the NUMBER slider.\n"
4 M; {: D0 {+ s                       "The setup has stopped.")* c  r9 E1 f4 U) a% Q
    stop$ [; ]% o& F; L  T
  ]: Z& ?  g2 Q5 w8 \' w: q6 f) v

4 n! b$ h( g) \- R  T  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 V# P$ N- @- a. C
  crt num-cars
* q! u; q6 _  Z1 Q# `0 Y+ l  [
& v( \/ z* [3 B, c' {& ?! T    setup-cars& K. N+ @/ x8 w9 W0 ~! M1 v
    set-car-color  T; C; A. }& \" V0 I/ d
    record-data
, X  N- v  y/ L  ], r% ?: C( U8 ^  T
* o) G6 c1 Y; X4 d& {3 v
  ;; give the turtles an initial speed
% E, n$ J# \9 Z, h! w" Y! y  ask turtles [ set-car-speed ]
9 N- a" X6 W6 f! q4 B6 g- ?- [& {& B
  reset-ticks% Y4 x9 v1 q1 W9 }
end
$ R4 W: X  W3 A. H8 J9 t
5 A4 Z* ~  c5 L* d) q;; Initialize the global variables to appropriate values
* X2 {8 O7 {2 a* B4 }to setup-globals
1 `7 ]  P1 z& _, \9 o7 c. {  set current-light nobody ;; just for now, since there are no lights yet+ Q, M; a* T& p, o* J
  set phase 0; X% t7 E0 o/ T5 t! G' l1 Z0 s
  set num-cars-stopped 0; r. w1 r; {/ u) M, G! ^
  set grid-x-inc world-width / grid-size-x- J7 l5 v3 |! Z' G
  set grid-y-inc world-height / grid-size-y
: r( W$ g" k) @9 S* r9 h0 |* T# [2 x  a5 g2 H1 k& o/ l4 O/ N
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary$ ~/ e( V- t3 \8 P$ e( n3 v
  set acceleration 0.099- V% w( Y3 \; D/ g" |+ ?/ S
end$ R4 y0 }* ^! j0 S
& y2 X3 x; @/ }4 D  b3 M1 b3 C2 m
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,* }+ q! }6 Q: D5 n* S. L" `" W# Z
;; and initialize the traffic lights to one setting
: |1 v, \! e$ @$ {0 Z# I; p" hto setup-patches. E% I+ M) g; d: o5 W' N6 l# w3 ]
  ;; initialize the patch-owned variables and color the patches to a base-color
% j6 p8 h+ h* w7 |+ Z0 l" _$ k  ask patches7 `6 e: P, H( I! Q4 S
  [" ^% S: i& |4 n% p# @$ p
    set intersection? false& P9 N1 j0 R! ^! q* y0 W* @  `! _
    set auto? false
8 I7 Q: }* j4 Q% a0 R8 |4 U    set green-light-up? true7 p% Z$ k# w( ^# z4 X+ i
    set my-row -1
7 m, l6 ^3 V' s! Q& Q    set my-column -1
% L) }3 @0 ^) c. L( x    set my-phase -16 O2 Q9 Y( M$ h" i
    set pcolor brown + 3
5 ], z' a4 r. K+ R) Q  ]
- \7 C+ z  ?% ?. N' M- H/ D: M% ^. b
  ;; initialize the global variables that hold patch agentsets6 o7 b  p! Z" l
  set roads patches with$ d/ i  n9 e$ s; L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ F, f- o7 @7 V, Z+ G. t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]7 L( Q; k; H% g
  set intersections roads with
- _* A' C* m* \$ |* ~: j; a! d- Z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and, N6 n9 i7 Y' }8 T1 e0 v! A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  v' L& C- F8 V% U
9 Z" Z) w6 [* i. Z% y5 E  v  ask roads [ set pcolor white ]5 f* v7 h; ]5 E# E8 L5 T
    setup-intersections1 b! V5 [3 K4 i0 r' g1 v6 Q/ ]9 u7 u
end$ b$ ~& U0 U) x" ~
其中定义道路的句子,如下所示,是什么意思啊?
3 N8 m( o6 ]  A! f set roads patches with3 ]* i5 o& }. n  b# w+ ]
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 v/ r9 [6 M2 V8 ^5 ?
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ J! i5 i, [! q" k1 O. i
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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