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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。# Q+ r$ U" [9 H! n
netlogo自带的social science--traffic grid这一例子当中,
! }( X& }# S( Q7 ?3 i8 K9 Vglobals# g# ^- p  Z5 [1 ^' |
[# I$ N+ O2 Z* l6 D! H+ |0 g
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
. _7 I9 t0 N' j! P, x4 ]: n' P4 c: Q  grid-y-inc               ;; the amount of patches in between two roads in the y direction" l! O8 k/ R7 C. L# Z
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if7 h' v* b& N+ A& ~9 H! l& _
                           ;; it is to accelerate or decelerate
. `5 P* g' V% V! g) y  phase                    ;; keeps track of the phase
. u0 Q- f; m* S8 k* Q9 D: N) W  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' c9 A7 U) ^# u! ]7 d) S  current-light            ;; the currently selected light  r! L6 F/ A: j, S/ d# }" Z5 }2 x6 y. A

. `4 t- H" l# d) V. v  ;; patch agentsets/ Z) n/ O. N2 V! [
  intersections ;; agentset containing the patches that are intersections
/ }0 ?- ^$ z9 H* e/ X  roads         ;; agentset containing the patches that are roads
3 C$ F* O" [# M]
" {4 Y( ^8 v* u# W9 m& q3 L. h1 p4 b4 e
turtles-own) t! q! m( l9 @4 C$ l5 J1 H
[4 Y) y& R% x  m$ F& O
  speed     ;; the speed of the turtle
/ A6 e6 S4 E% _0 |: H$ k9 |  up-car?   ;; true if the turtle moves downwards and false if it moves to the right; `0 w( P8 t: u0 N' s3 L
  wait-time ;; the amount of time since the last time a turtle has moved5 M0 Z8 E; Y7 E0 g2 a$ {* b
]' l9 }9 V* w7 n. I6 {& x
7 Q$ p- Y) t/ c+ ?; F3 l. A
patches-own
2 w7 p# z, i5 r+ L( i1 F[4 `- E. ^% v  h$ M' u9 N. y
  intersection?   ;; true if the patch is at the intersection of two roads( W6 X6 ?6 M2 t
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
( F# [" Z1 }0 _4 @3 P                  ;; false for a non-intersection patches.( Z0 k( f  S5 S" c
  my-row          ;; the row of the intersection counting from the upper left corner of the
0 Q' H+ p/ L3 z& v                  ;; world.  -1 for non-intersection patches.7 X/ \0 x8 ~) T# M2 k4 ]- {
  my-column       ;; the column of the intersection counting from the upper left corner of the  D" m; I) y) @
                  ;; world.  -1 for non-intersection patches.
1 A$ M/ o, D) N6 @6 ]  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 e1 U: U4 E/ M" u/ k  k  auto?           ;; whether or not this intersection will switch automatically.& Z! ]* J% j  r6 X) j
                  ;; false for non-intersection patches.$ u8 x# P5 L3 ?4 o# G- R
]
7 U: }9 I; Z. O4 n$ A1 y
! K) z" z+ G- x, C; F# R, d/ a8 L( N2 o% H$ z* M7 d
;;;;;;;;;;;;;;;;;;;;;;
$ B) r( [2 [) d2 S% G, h;; Setup Procedures ;;
, R! V  C6 H8 v2 }* k;;;;;;;;;;;;;;;;;;;;;;
8 _( @% m* S. W$ ^% B/ @4 N* x9 E+ C+ Z0 E
;; Initialize the display by giving the global and patch variables initial values.  L" A" {6 P: E0 I3 E
;; Create num-cars of turtles if there are enough road patches for one turtle to
. g" i, `1 }3 T;; be created per road patch. Set up the plots.
) Y) i" W* d1 bto setup1 E, z) t& f5 Y3 g9 Z$ @: L
  ca* R) D. F9 Y: d4 Y9 e2 c" f
  setup-globals5 w  D% e, C- [0 r! S' ?# }
, F8 k" P/ w* ]3 L
  ;; First we ask the patches to draw themselves and set up a few variables8 s% A$ k9 ]# U7 O& @0 J
  setup-patches% w' S& ?( d" U4 k9 H
  make-current one-of intersections, V, U5 g3 w" F9 R* N
  label-current
, l* Z6 ?' D  J3 A. V+ b" i2 S& F, M. a
  set-default-shape turtles "car"
) _% Q2 f4 i( W
1 ~3 m) |5 s9 M; y8 w7 v/ l' K  if (num-cars > count roads)* j4 m+ k3 o; P) P$ \
  [
# J* a9 |: m& v  V% U* B* z    user-message (word "There are too many cars for the amount of ". f: X! G/ s' \% @1 h+ d2 B- z. K
                       "road.  Either increase the amount of roads "" |2 o- r& K0 I3 ~, A/ j
                       "by increasing the GRID-SIZE-X or "' V/ ?) q& @0 l- i; ~
                       "GRID-SIZE-Y sliders, or decrease the "7 l, N- V( B1 y1 \
                       "number of cars by lowering the NUMBER slider.\n"& t" f: I5 g% T4 {) t+ y7 h
                       "The setup has stopped.")/ c$ e6 o0 a: K. y8 {
    stop
! B" @2 P; n0 n7 M# J: X+ d  ]
1 H6 b" M( J" ~! x! Y1 l. f
2 u3 b0 x4 K/ K4 g  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 i9 E7 f  ~% @" N; x5 v
  crt num-cars
& f% X, z. U4 u/ H  i  x; M  [
% b: j! ]  e( Y* e9 p% x7 p8 J    setup-cars( q% \  `! L' L! {% M
    set-car-color
. w3 I# k* S( C6 s    record-data2 P! t5 e2 T+ _9 S+ G
  ]
  P. J! _$ ~3 r  m: z, n" S2 a( a* [' D& z
  ;; give the turtles an initial speed% h; Z+ h9 V2 G) _- Y% ~
  ask turtles [ set-car-speed ]
9 V/ }6 Q" s) c9 K# A( P* K% V8 v3 |* U( `& |* J
  reset-ticks6 m1 C( U2 G0 w: v8 m- W8 v+ O
end$ t6 R3 ^/ j+ G3 _$ u$ P
4 J& f6 o& d9 t8 l+ ^
;; Initialize the global variables to appropriate values! a* s! y; B. A) w. U
to setup-globals
, D  D* o7 H7 S6 Z7 H0 `( G) q  set current-light nobody ;; just for now, since there are no lights yet0 e+ d9 d  t2 v8 Y. \6 Z% x
  set phase 0
, u& _4 L' Y6 p4 B: k/ E  set num-cars-stopped 0* k5 B! F8 |. O2 Z
  set grid-x-inc world-width / grid-size-x
+ ]/ s+ {+ v8 @7 J6 U+ i2 E  set grid-y-inc world-height / grid-size-y
3 A$ e& ~3 j) l0 B0 F
' H% J* z4 j* J+ N% P. P  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, g9 h2 S# b9 |, a& _- x
  set acceleration 0.099
1 m/ c: P  H' q5 F) j" e. kend4 j  j+ j7 J% w

5 B; G+ D8 s% o2 ^+ v* X4 m8 z;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) G: W6 f! K/ S3 @) ^;; and initialize the traffic lights to one setting
, N. ]0 P: u! T0 v3 E! `. ?to setup-patches
+ P1 N3 L6 L4 x8 S. H* h; G! @% u  ;; initialize the patch-owned variables and color the patches to a base-color1 ?% j7 T5 `* g6 n- a7 p; l
  ask patches
# @* Q- y, [) p; N! A. ^, }  [% {0 e0 P8 A" |  r. h* Z
    set intersection? false
; F7 d: _9 u% U3 X2 C+ o    set auto? false: u) s6 I8 e+ M' K, U
    set green-light-up? true
- C0 P# f$ D% B, y& n4 |1 i    set my-row -1
! G$ Z) `+ ?0 E; g& k% |3 ^    set my-column -1  @0 W7 s( N1 c+ |$ G: I* x
    set my-phase -10 X% n+ S2 G2 [8 w7 s
    set pcolor brown + 37 X+ w6 ~' k+ `" Z
  ]5 n# Z* A* k4 _( U+ ?4 V0 }1 _
' j! ]0 c% b' x) _+ B3 F6 n$ f, D
  ;; initialize the global variables that hold patch agentsets& @# }$ c4 r" [5 x, x
  set roads patches with: A3 i1 {5 m/ `9 v( }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
) e  O& l# W- D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]* V: G/ y2 q' H6 v
  set intersections roads with* Q$ f1 S% ^+ g) F& t, i1 A) h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 J( t) ^# R& b. o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 m& D5 q  y/ i7 |& h* `% N3 x) I5 ?4 y- T) r( m/ h* V8 D8 w
  ask roads [ set pcolor white ]
6 \0 ~) d% [1 F7 O# V+ Q    setup-intersections
4 @: o& @( v" Y. pend
0 U% c4 s9 F& X& d6 Y- M% H其中定义道路的句子,如下所示,是什么意思啊?
' R6 X! R+ t+ ?- h5 C, y set roads patches with5 F7 M+ m( ?+ z4 s9 ?: |. \+ n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or1 L% J' k# N* R4 r! t. Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]5 k! o& J3 u8 U, X+ R  M
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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