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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。: u4 Q& T: Q4 ]% ^; B
netlogo自带的social science--traffic grid这一例子当中,
8 k6 z7 R1 \; gglobals
, i# L/ a* B; N7 f) T1 S& y[
; ]) Y4 U5 j: q" k: A) C  grid-x-inc               ;; the amount of patches in between two roads in the x direction) n( a- G& j9 \! b* W8 T  J( d$ n
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
7 J1 P1 C7 U& b) `( c& ]  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& U- w) N8 Q) u; {3 P/ C4 ]                           ;; it is to accelerate or decelerate
; `* H; D# z2 j; z  phase                    ;; keeps track of the phase8 [: ~3 L0 l+ n. k. f
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ _$ G* s$ T, [6 S
  current-light            ;; the currently selected light
, X4 z. Q5 `# I$ x6 G7 e8 ?+ y% W
+ ~. p3 {: t, x( v5 D  ;; patch agentsets" `  ~0 B  k, j3 r3 y
  intersections ;; agentset containing the patches that are intersections
+ g: A! y/ `# F/ y* X8 c! P0 N  roads         ;; agentset containing the patches that are roads
; _$ ]: p& w, Q]
8 _, {% u% v( n: {. @. q# a) D8 ?4 T
turtles-own& z8 q7 i. d% O) _
[8 d6 l( @5 m( ]$ o
  speed     ;; the speed of the turtle4 a3 S9 h$ i9 _& u: E
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
1 ^" D" R" T& @  wait-time ;; the amount of time since the last time a turtle has moved, q# c7 U8 w; W
]/ T8 \4 D9 C  o7 M  g2 j3 f- E

. g( h- u( Y; q; ]patches-own
& }3 [6 H( x# H, M3 P[& r6 E8 }& {, k/ Z( i4 Q0 M
  intersection?   ;; true if the patch is at the intersection of two roads: h) z1 {' ]# R3 X  k
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* u! j' z1 y* G' _: U4 `4 y3 {
                  ;; false for a non-intersection patches.% G. X6 R/ f8 o/ V
  my-row          ;; the row of the intersection counting from the upper left corner of the
- s" r2 X) H5 _3 ^; f: {' I3 T                  ;; world.  -1 for non-intersection patches.
5 n( u4 P6 j$ Z4 w& M  my-column       ;; the column of the intersection counting from the upper left corner of the
4 @+ Z" B5 r, `: @1 U  C                  ;; world.  -1 for non-intersection patches.6 G3 U) n# Y4 Q5 ~/ |
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% c: N9 X8 s4 @* g9 I  auto?           ;; whether or not this intersection will switch automatically." |6 Y. E& O$ o* R8 m9 E, n$ ~# F: |4 \
                  ;; false for non-intersection patches.
) E1 v" D: v, ?7 ?' N3 a0 J]3 H- D* b- o: \* ?) Y, G( \# ?

) r' N* L/ X+ X: c
2 f5 ?1 J# i4 ?# v;;;;;;;;;;;;;;;;;;;;;;
+ V, v" m% \0 I8 S5 Y;; Setup Procedures ;;
9 X' O% e; a" N0 F;;;;;;;;;;;;;;;;;;;;;;
! Y6 P5 l  {3 q5 ~# [/ o+ x% R% J3 ]; T5 h
;; Initialize the display by giving the global and patch variables initial values.
. b1 e$ D3 u* U* M7 B: i. {;; Create num-cars of turtles if there are enough road patches for one turtle to
2 z/ M8 p0 [: B$ R1 C. y, J  J+ P! h;; be created per road patch. Set up the plots.
: q7 p$ o+ |; v+ a0 r2 Kto setup
1 k5 K; }4 o5 t- I$ W5 ]  ca8 N2 v; Z8 M& d+ I4 @+ s& l0 d
  setup-globals" Z: J1 N" z3 {! ^8 u* ~( n) X
( f% ~4 j% V1 S- {0 p2 C
  ;; First we ask the patches to draw themselves and set up a few variables
$ F. N( o8 Y0 }* d8 N& }  setup-patches
1 w% _' F7 [5 {, G7 k8 ]7 h7 r  make-current one-of intersections
# L9 {6 @3 N/ g! G6 R3 D  label-current
5 L4 ]$ s% z. B5 |, v+ F/ b# Z
$ P& o9 t: E* h0 N  set-default-shape turtles "car"+ K6 {2 w( F2 w% l! S
5 S8 F* v( a' }9 ]
  if (num-cars > count roads)! ~% a# p$ D; X1 r, \* w& o1 e% i
  [: n, t- [4 [6 L$ c3 Q* k1 `
    user-message (word "There are too many cars for the amount of "- b2 e, F' L" l# Y$ S; m* }
                       "road.  Either increase the amount of roads "$ w7 S; @9 |$ j3 q/ o/ @
                       "by increasing the GRID-SIZE-X or "
# z' B9 I" e, R8 _                       "GRID-SIZE-Y sliders, or decrease the "7 }% ^: `0 `. d
                       "number of cars by lowering the NUMBER slider.\n": l6 o; `0 Q6 z8 ]0 o
                       "The setup has stopped.")
4 z* M1 d% _4 l" Q9 K/ |+ C. T    stop; p' d& Z9 B( h/ j- ^1 x
  ]2 W" f' Z" U5 q; n
0 y& Y4 ?. e0 b/ m
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color" D  j4 U6 y3 s
  crt num-cars( l. ?/ W3 M2 E% K$ b. }
  [
' y: E8 s6 }% b7 _0 K    setup-cars
' x' D$ ?3 W3 ]2 e3 ^    set-car-color
8 S! K6 w# H+ T. a    record-data
- R0 \, W8 L% D1 ?, H  \  ]& s2 }! _" |% s6 `; G

6 B- x* c0 ]( P2 {6 x% c. N. G  ;; give the turtles an initial speed
' |2 |1 k2 M5 w2 B8 {* X1 R" c3 V2 d  ask turtles [ set-car-speed ]
  }" r  G, a5 q7 {/ g/ q8 e) `  T
  reset-ticks
9 S, H( A6 U" |- ~, q' b1 _' t3 Eend3 W2 h0 {# k/ @4 F. i% G9 j0 y
& h3 g, T) w0 G- h
;; Initialize the global variables to appropriate values
2 {  ^' M7 n0 Y% \; J' g1 Bto setup-globals0 e) F6 ]. g3 m3 {3 T; T1 ]- r
  set current-light nobody ;; just for now, since there are no lights yet
- |9 m! h; @4 L) I0 W4 M  set phase 0/ N& u  J+ o: l3 _) ^3 h9 b
  set num-cars-stopped 01 u' ~9 ]4 i; [+ F! \
  set grid-x-inc world-width / grid-size-x0 \4 }2 H: Y/ m, y
  set grid-y-inc world-height / grid-size-y
6 T0 B4 {% o( w5 y3 j6 f2 J1 e
' d1 D; f- \& H# S% Z" f4 I" k1 l  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary. T" Q+ a% s! s( k
  set acceleration 0.099. \; G0 x9 z) z! ^
end
9 d5 D9 c: L& T
2 s3 \+ F5 W: D+ P6 N;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 z  M$ e% u, Q
;; and initialize the traffic lights to one setting3 e/ F- @1 ]& R3 s  n
to setup-patches6 \6 X) _4 }. _4 p- O6 U$ h6 d
  ;; initialize the patch-owned variables and color the patches to a base-color
1 P2 F7 K1 U1 ^' J. O4 E2 N  ask patches7 u0 A. o/ ^5 s) B
  [
$ r1 W' o/ @% L4 ^0 c    set intersection? false+ l3 r9 v1 o: l7 i) w7 C6 X/ F
    set auto? false
& Q& S0 g4 s6 P6 @    set green-light-up? true
1 M8 O+ i' t- Z6 c! }% h8 L2 H- O7 ?    set my-row -1$ H4 B: P+ T8 l  b& {9 Z8 w
    set my-column -1
9 X4 W; [. j2 p, ]& l( U( {1 N    set my-phase -1
7 V: H) I5 H4 y. G! i    set pcolor brown + 3. s+ m3 h' ~3 N* A& P
  ]
/ b0 @4 W. e' ^
6 o$ D* f! C* o& y% D  ;; initialize the global variables that hold patch agentsets
2 _- A/ A+ _  G* @: r0 H  set roads patches with' H; w9 \5 }+ s( q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or" m4 O( p. O: {9 H$ P
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 H5 `$ u. c( ]- \1 X) G  set intersections roads with
* m: x+ ^% x) V2 U: _4 I( t3 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
( {. y3 l5 r3 I% D2 P$ h% |9 F# R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ s5 E6 A+ M7 o8 @* S. q

. f4 F, d# x2 j! I2 I  ask roads [ set pcolor white ]
$ P9 M9 K( y1 v, t0 p5 S    setup-intersections
  V2 e" f0 j% |$ _2 O- Mend5 g+ s, K3 x; ]* M& ]0 c. t# P/ F
其中定义道路的句子,如下所示,是什么意思啊?
( q( |5 D6 N& T0 T8 U! N+ \1 E# r set roads patches with
: n: Y, f! y) y    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
4 W" u, ~! O: J6 x! v- P& }% x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
/ t9 k. E4 E9 ?  V3 A% h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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