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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。, t& L7 ]+ e% u( M3 H; |- W6 T/ u5 q  k
netlogo自带的social science--traffic grid这一例子当中,* @: C* K+ S, U6 ~% l; P" d
globals; P8 |' l' ]" ^0 P/ K6 c, u1 o  k4 R
[. c1 L0 H) `8 ?7 G* U+ T& b
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
0 `( G! D, @( L+ U) U, B  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) z4 C/ A) W  L9 Y2 ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  R! z! c$ V0 I3 |# W
                           ;; it is to accelerate or decelerate* s9 P7 Q" X) N
  phase                    ;; keeps track of the phase
" L: D& Q" H7 d. T4 Y9 X, O5 H* g  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
9 H; m2 U* w2 p4 a  current-light            ;; the currently selected light
1 b& k+ ~1 b& G( v% [6 w9 x% R1 M: f, f4 }% t: t2 H6 d7 w
  ;; patch agentsets/ s' J0 Y1 S0 c* w+ p3 h7 a" b
  intersections ;; agentset containing the patches that are intersections8 m3 {$ R( x, ~- f2 |- F" t$ k3 u7 h8 [
  roads         ;; agentset containing the patches that are roads
# l! E2 ~" s5 `! `]
0 s7 o  I) I% c; N6 i" C* p) V) U! z
turtles-own
* w( Z. B$ @& M3 Y; U) j[. b9 l2 |$ I8 r" [! D- ?% b
  speed     ;; the speed of the turtle
& L8 ^: g+ B0 H* h" ~! ^  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
* G  l: l- Q3 d& F% h( E: W* s  wait-time ;; the amount of time since the last time a turtle has moved2 n# ~5 ^2 _' }% n
]
$ V" i8 r: J; r0 Z+ f, h! r4 w6 \+ t& j) @  m, o# k
patches-own
" I$ ^# x% t' }( p0 g- ~' n[
7 v$ V7 O( w+ q( U9 l  intersection?   ;; true if the patch is at the intersection of two roads' C9 P5 K  v; v4 k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.' r& b- R! D" C; c4 w
                  ;; false for a non-intersection patches.0 `7 S1 F6 V5 M+ O( d" }
  my-row          ;; the row of the intersection counting from the upper left corner of the" b. {0 O1 m# F+ s& {. S- F
                  ;; world.  -1 for non-intersection patches.
4 ^: R5 z* L9 U, ^  my-column       ;; the column of the intersection counting from the upper left corner of the
: m$ z7 F/ W- j. y5 e. p8 |) n                  ;; world.  -1 for non-intersection patches.
, T* N* Z- u; |6 W  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! Z  w" c8 r5 _; J
  auto?           ;; whether or not this intersection will switch automatically.9 k$ B, L- a$ x7 s2 J6 }
                  ;; false for non-intersection patches.
3 i, m) g0 L6 F/ [7 u/ J]! b8 Y" Q9 Q' Q

# ]1 t8 d; u9 `0 y
5 L$ w) A/ M& [;;;;;;;;;;;;;;;;;;;;;;
4 T. _+ x2 L4 Y$ k/ ^;; Setup Procedures ;;) u! s( B' Y6 G1 Z
;;;;;;;;;;;;;;;;;;;;;;, D7 J, g! t9 k2 |+ U) a: N

6 ?. g, J1 x0 P/ ?: C;; Initialize the display by giving the global and patch variables initial values.; q6 Y/ M) Q' `) a1 V" o& Z6 @
;; Create num-cars of turtles if there are enough road patches for one turtle to3 k" P, x8 m2 u/ l9 h4 a
;; be created per road patch. Set up the plots.9 @- \  g  r$ d
to setup' s4 n: _5 ?( ]1 J; _5 D
  ca
2 Y" ^/ X( U8 l1 j9 [# B4 ?  setup-globals
% o  m) {. ]" n( R6 Z5 r
" W. H2 \# N# u( \5 q3 Y& l  ;; First we ask the patches to draw themselves and set up a few variables
# z. P7 p! p% a" _  setup-patches. S$ E+ k  P: Y" K8 z" R
  make-current one-of intersections
3 j. f- E& J* Q  label-current
1 i7 w: _& r  M8 o5 G0 ]) q3 M& m$ y5 J
  set-default-shape turtles "car"( ~! j& q7 h* O" B7 ^5 X

  y9 Z& {! r" P! p  if (num-cars > count roads)
0 }$ r* b9 H4 C0 |( K  [
+ j7 E! q! I" I& w! u    user-message (word "There are too many cars for the amount of "
% I+ b3 v8 U$ b/ M                       "road.  Either increase the amount of roads "- c4 G& V3 R: a/ |+ o# B- B
                       "by increasing the GRID-SIZE-X or "
0 }+ t) i/ I6 M                       "GRID-SIZE-Y sliders, or decrease the "3 k' _0 I- P" {2 C4 C' ]  W
                       "number of cars by lowering the NUMBER slider.\n"* p( h1 D  J1 e, T
                       "The setup has stopped.")
" F4 H  B( O6 T7 o: V, u    stop9 N% ~9 d2 K/ n9 Z& {- [
  ]
0 p: G' R9 a6 [) d( |
! a  x9 L+ L) r1 O  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color$ z7 w- a& z9 q! n8 u
  crt num-cars7 b4 H& P2 N, O% Q5 P( t! {, G
  [2 i0 a& j8 o0 Y; |0 z
    setup-cars8 _) [6 O- m* I2 r5 I+ m% L
    set-car-color) e* i8 w* b/ p9 ~  M- G
    record-data: `; k) [4 }* a$ ]8 R
  ]3 p7 H' A, T. K( d- y' ~

6 C! G4 M/ \9 C  ;; give the turtles an initial speed
, t9 g, a2 _4 H% _$ @3 c  ask turtles [ set-car-speed ]
) H  I' W8 _, Y- Z3 Y* N5 N1 ]2 G
4 T3 M4 X6 H( Z! Q9 U  reset-ticks5 ^$ G0 `* z5 h- W& r" T6 X2 l; V' Q
end$ N8 Z4 A. z, X& x* t8 E8 F

' q7 F9 S5 k5 G8 [;; Initialize the global variables to appropriate values
! b- F8 V2 Z7 d2 @3 S, g: Oto setup-globals; p1 ^- ~) e3 p& Q
  set current-light nobody ;; just for now, since there are no lights yet) X* ~( D' P+ A, P5 N3 \
  set phase 0
9 b( Z& w' g9 x- j- r  set num-cars-stopped 0& R- S, z+ V* A5 S! Q  i
  set grid-x-inc world-width / grid-size-x1 d0 I8 R( H+ s! E4 u  ^( a1 p
  set grid-y-inc world-height / grid-size-y
: [& c2 C) w/ @9 [7 C; |' Q/ ^2 Y$ s9 e- o  _
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" f4 A3 f  H& H. N" D( Y8 }  set acceleration 0.099
; \( O& U9 u& v2 Nend- c) X+ g7 H6 {8 Z5 T6 D3 ~) q* X

& m& T6 Q8 B7 F6 |;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
7 H% I6 N4 b8 a( `4 v+ ~! ^;; and initialize the traffic lights to one setting/ a4 L! c* w, h
to setup-patches/ F% D  Y; l; [: a- ]4 p  K
  ;; initialize the patch-owned variables and color the patches to a base-color; ?- N7 I' M1 \/ n- m
  ask patches
0 t  l3 W+ Y3 U6 x  [
" l, _* h/ |5 K% S5 ~1 V- ?$ D- i' F    set intersection? false
/ v" H9 Y* }' a9 q0 a% `  p" I+ O2 N    set auto? false
9 b$ Z# Z5 Y6 L9 e6 ~& ]    set green-light-up? true
, j# k7 q; J( H5 o    set my-row -19 t$ b* k8 m4 f, I/ n# b" G" ]
    set my-column -1
" i- U  K3 F: l) s    set my-phase -1
: M0 ?  }4 Y) O    set pcolor brown + 3
9 y4 n2 Z7 `+ \: r: z% d  ]
) h& Y4 R% E) ?; y
) v* I! \1 V% Z" N! j& y  ;; initialize the global variables that hold patch agentsets
, E( Q. T( p$ B3 o& I  set roads patches with
' r& t1 l. B2 Y2 a  N- |. J; U    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
& m1 P. Z) \; h) o5 a6 o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
$ V; U% P% v! [6 S0 _( ?  set intersections roads with
5 s- L8 ~! Q6 w% w8 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% |  @! O" {$ i    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]  o* B$ }2 |- y7 f# a7 N

( A% Y: x% P7 h7 y5 U  ask roads [ set pcolor white ]
/ b) l/ A( Q2 H3 H/ S/ x9 L+ W    setup-intersections
8 i$ V( E0 a+ v* j4 n6 Xend
5 }. _" E% S  |  B  r$ H( f" X其中定义道路的句子,如下所示,是什么意思啊?5 ]# c$ Q5 p! E- I$ |- R
set roads patches with
( W) w  V4 k) m2 b5 }    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
# m. J, c& v6 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 ^5 G! f# a' \; _% R; W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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