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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。9 a1 U. Y' ?3 t0 S& O" j9 b5 K
netlogo自带的social science--traffic grid这一例子当中,  Z0 \/ a& M$ w# R" c& ^3 [5 L
globals% b2 K& [$ E* X+ C
[
4 p6 I4 ]! B! u1 u  grid-x-inc               ;; the amount of patches in between two roads in the x direction
* v1 [) I& [2 R$ A: f" A1 d* L  grid-y-inc               ;; the amount of patches in between two roads in the y direction
) w- x: E! k0 {; L  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
) q( i+ u. G8 a7 h- x0 y% n                           ;; it is to accelerate or decelerate
( a& e- l6 g! y& ~  phase                    ;; keeps track of the phase5 b, F% d) B% l$ |, Y8 F/ Y
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; y  j! v! Q. |7 f2 L0 k( a
  current-light            ;; the currently selected light
5 [' R' _1 _4 ^8 A5 L( Z& V+ K" Z3 Y8 J( w. J
  ;; patch agentsets# V7 Z6 a: b5 j. H8 w" s. Y. _
  intersections ;; agentset containing the patches that are intersections( {& N+ `* \4 B8 o, J  Z5 [
  roads         ;; agentset containing the patches that are roads5 D2 ]  m: z& N$ n* a. W' s
]
" F+ J" D1 o3 ^4 w/ E7 n# |
, P% E0 ]" u( Z& u8 A" G( xturtles-own
  E- M4 f& @" e+ i& {- ~3 r  H9 \[
2 t0 A0 }0 s$ F& G  speed     ;; the speed of the turtle) y( [4 ^. ?5 k
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right" s+ }: C* k% x7 }- R8 N! ]( \
  wait-time ;; the amount of time since the last time a turtle has moved
, y+ ?5 y$ X( I5 _/ h]2 E) J8 p, k; n, S) H' Q& Y
8 x2 I# [  L5 h7 p; I+ J
patches-own
# v  G5 r3 D( R" z: r0 h1 U[
& D6 v! k, }: Y7 r0 Q2 o  M: T) A  intersection?   ;; true if the patch is at the intersection of two roads
7 `/ M9 w% ^. k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
/ J. C5 j0 [8 K" H  g" U9 j3 {                  ;; false for a non-intersection patches.
: J; b$ S- n" m: b  my-row          ;; the row of the intersection counting from the upper left corner of the- R0 D8 h2 Q; v$ [. u/ r8 G
                  ;; world.  -1 for non-intersection patches.% _) M7 p7 O! \% V
  my-column       ;; the column of the intersection counting from the upper left corner of the4 |2 ~7 Q' _" v8 u
                  ;; world.  -1 for non-intersection patches.2 {( [7 _, Y, P# I: l
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 I" i* |- l# ~7 U
  auto?           ;; whether or not this intersection will switch automatically.8 s) d' O  E% L, N
                  ;; false for non-intersection patches." ~8 m# }8 f2 S4 J& @
]' Y7 P( J+ T  r  d6 T5 [' T8 ]. t

" G" K' ^0 D% e0 @. I
; j& n* T: u, B5 x;;;;;;;;;;;;;;;;;;;;;;$ [/ Y% a+ i  F- N. ~7 R
;; Setup Procedures ;;4 p# b+ p$ N( P3 ]3 N
;;;;;;;;;;;;;;;;;;;;;;9 l% H; s2 D8 U3 g& ^( ~# s" H
6 z( b5 d$ n+ ]7 Y0 M* M7 y
;; Initialize the display by giving the global and patch variables initial values.: G$ d, x. R  K0 w7 G" n
;; Create num-cars of turtles if there are enough road patches for one turtle to/ q' f) e& b' F1 M: A  r1 S
;; be created per road patch. Set up the plots.
4 V* \3 K9 H, @8 Pto setup" o$ L# u2 n8 ~' E; D+ ]
  ca4 W# z" R5 J" |. Z. X3 m2 Z2 x
  setup-globals( ?. c# A  L/ n8 [, }' l) E

$ C' T4 e$ e/ X- v- v) @* A0 Q; K  ;; First we ask the patches to draw themselves and set up a few variables! k, `$ ~5 w+ @2 b6 N& s% S
  setup-patches7 l  b' _5 Y. D: S! x. t+ r
  make-current one-of intersections! Z8 {, i/ i  e2 {6 ^
  label-current) K1 d2 m. L7 F" e' H% e

: S4 p) |# r+ X; u8 J  set-default-shape turtles "car"
1 Y) O2 p4 X- @" ^1 F) p8 \! w6 B: [4 B4 h+ i7 ], ~
  if (num-cars > count roads)# ]1 @2 |1 u  m
  [& u5 w) ], `& h5 _
    user-message (word "There are too many cars for the amount of "8 o  _! q4 w3 X* b  Q; |2 g
                       "road.  Either increase the amount of roads "
3 t1 d( |  q0 r+ Y% d5 ?8 v                       "by increasing the GRID-SIZE-X or ", \2 {, x, s* R2 {" r6 [
                       "GRID-SIZE-Y sliders, or decrease the "0 Y- l  m2 h, a
                       "number of cars by lowering the NUMBER slider.\n"
4 Y7 T; m0 M3 Q* p& O                       "The setup has stopped.")
# K8 l. g: ?% B6 g0 I/ U& _1 }    stop: @/ l4 Z- d; J" s$ U  E5 [
  ]
+ f, x6 B  r( s! p% O; D6 [+ }" ]2 q  @2 d* N
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color. S; m# X( y5 Q5 j+ F  A: E
  crt num-cars; Q" q% h' q. Y
  [1 m' j& |  }! f4 p9 I
    setup-cars( [' _" |% f! Y& T
    set-car-color
/ b7 f: \$ S: x9 g) |8 E+ T+ w* ]    record-data
# r* Y. K! n4 @3 O- r  V- _  ]/ e$ E; {3 u- @+ ?

3 m, d1 P8 T  y/ J3 O  ;; give the turtles an initial speed
+ B8 b3 x  t0 g& E  ask turtles [ set-car-speed ]" D) _# q- Y, \/ w" O% z' B
" g" q4 ?7 @  d; d7 q
  reset-ticks; E8 s' V! j' M' x( o9 ?
end& ?9 r0 m4 K- Q. m# ]: F" ~3 O
, b& f: Z: m" y8 @0 y* T
;; Initialize the global variables to appropriate values
6 n6 d( b: B, C7 x0 ]7 V- Fto setup-globals
9 Z6 x9 F0 v* |0 D7 q3 F  set current-light nobody ;; just for now, since there are no lights yet
5 N' \! B6 U* j$ R8 k/ D) X  set phase 0
! U* L# Q/ {* ~  set num-cars-stopped 06 k  @) d! @1 J6 z
  set grid-x-inc world-width / grid-size-x& W4 \5 S. d0 i8 B9 d
  set grid-y-inc world-height / grid-size-y
% N, ?4 ]* N4 @# O  [2 G/ F4 c7 Q: o/ z; I; R' N: Z8 }. f
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
% i( ?6 t" s& K& S  k  set acceleration 0.099
2 _8 y1 f9 q" i- n7 ]- Tend! U# K" F( Y8 H2 o; P+ R6 R
5 Q* o& K# |& P7 @
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  t, o* o  Y% C% C! M;; and initialize the traffic lights to one setting
, h% ^) k# E+ H" [to setup-patches7 }- _6 }9 _0 A
  ;; initialize the patch-owned variables and color the patches to a base-color
+ a. ?: h5 C6 v7 ]6 ~2 c' N  ask patches
; O/ j7 T/ t& N8 e4 V# g, }& P/ |8 d  [; E- K+ B9 S8 w4 Q- u
    set intersection? false
- n8 `0 q2 P2 R* c    set auto? false
) x& H6 l- A* s, m$ G    set green-light-up? true
  o5 N6 ]6 ^8 ^* F# O7 m    set my-row -1) m8 }% g3 g& P) `
    set my-column -11 Z1 q1 N: _& l2 W+ o$ R/ [
    set my-phase -1
# j' h1 F. v, M% S4 x    set pcolor brown + 39 X; o$ A5 h. X! D3 j1 ]4 l
  ]0 o, J' Q! |8 k- J

5 S  v3 O* D3 Y4 u) @  ;; initialize the global variables that hold patch agentsets: J8 p" p# e; r& {! \2 p9 y
  set roads patches with
# m) P. I8 c2 K7 q& N3 L/ p6 T- B3 w    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! Q3 @# V  ?  Q0 X    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: x1 h' Y/ J4 G" g1 z0 W& B  set intersections roads with
  r* u0 F& V9 W2 Z( W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 X; r  \7 F' H: @, n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 d/ F) ~- o4 v
0 ~) f, m6 N/ a4 H  ask roads [ set pcolor white ]
1 O5 y6 Z; b; u# d& H6 P6 N0 r    setup-intersections
5 A1 R. V/ g1 d* w2 j4 }end
% g- ?% I4 a! |  F7 r其中定义道路的句子,如下所示,是什么意思啊?+ Z  B# B. Z8 B5 C
set roads patches with" \! k+ b# ?7 [+ l0 w$ L  d
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: l* n  I' D' l' u, b/ C; @; {: b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; r" M) S6 {1 _- T
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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