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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。
- o/ V. a  Q0 }. k; F& b$ jnetlogo自带的social science--traffic grid这一例子当中,+ }8 l0 m5 Y& `  U$ h6 Z
globals
1 G" q: h. k$ O[
! n4 D  g, {0 m: E# P# k% Y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
% ~% j5 Q9 E, y/ e2 A( y  u+ O. U! w  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 g, p9 W3 M0 D7 e$ t  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; S% s5 I1 m8 X  B' t  s/ j* Z, r/ V
                           ;; it is to accelerate or decelerate
3 S  P, n. f: n+ P+ H  phase                    ;; keeps track of the phase) k' {! m. Y0 c0 i- u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
8 K0 p% u$ L2 s" d, @; s  current-light            ;; the currently selected light
3 _( _" e, Y4 _* q, ^+ B8 r2 l" n  O8 O
  ;; patch agentsets! M7 {+ r: m6 K& t' A
  intersections ;; agentset containing the patches that are intersections9 R" G% p0 v! S& }) j
  roads         ;; agentset containing the patches that are roads
1 _5 G7 x4 o2 G6 X]2 H& p& Q/ w" Q2 w, ?) \7 Y
1 t, q& V4 c- k; f
turtles-own
- N  w# Z! C. j) P% E[
8 c1 ?" E4 h" l6 @1 c/ x6 a' D  speed     ;; the speed of the turtle7 o, N- d, p: ]/ T( k$ Q0 B
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right9 V9 ]/ N+ Y9 j2 e
  wait-time ;; the amount of time since the last time a turtle has moved' B! c2 S* U. v) E1 i
]
$ Z% Z9 `1 Q5 H4 I) v7 n% Z5 V
) E* m! c: _! j- ?patches-own
# Q" t6 l- U" U- |/ N) b[
2 x" v$ {4 J+ h) a1 f' [  intersection?   ;; true if the patch is at the intersection of two roads
. }% w# k% c9 y/ V# L- ^  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
# K# t- r9 L- E( f                  ;; false for a non-intersection patches.
  t8 b. g! Q' Y8 u9 ~  my-row          ;; the row of the intersection counting from the upper left corner of the( `8 D( a  y; t8 m+ H
                  ;; world.  -1 for non-intersection patches.
1 Y/ f/ z  |: i) q8 O  my-column       ;; the column of the intersection counting from the upper left corner of the4 e6 j* o8 w, V5 \. e# ~( _
                  ;; world.  -1 for non-intersection patches.
# e5 \' @5 H+ I% p5 d  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
% F- M# s2 g' M& v  auto?           ;; whether or not this intersection will switch automatically.
7 q4 e* u/ [' ]- y' u5 S                  ;; false for non-intersection patches.
  D* \5 ?, B( e& ]3 W], ~  d' `! X8 p6 z- @1 Q' b( z
  @6 l# b/ B& J7 S3 F& m! N

  h, U3 N4 _9 {: W0 t9 I;;;;;;;;;;;;;;;;;;;;;;
! m4 }& E' T5 s$ ~0 B7 O# I;; Setup Procedures ;;
0 w. z! o- ^9 T( t$ d$ t;;;;;;;;;;;;;;;;;;;;;;
7 L9 f4 H0 l* A: y$ c3 \8 N9 |; S" k! g& I; ^2 K4 J0 m1 [
;; Initialize the display by giving the global and patch variables initial values.' @) v  a7 T; U
;; Create num-cars of turtles if there are enough road patches for one turtle to/ a5 h! n3 e5 @1 q- S
;; be created per road patch. Set up the plots.3 k/ C( ?1 _1 `& N; X) T( [
to setup
# `& F8 Z) Q* ?7 P5 A) u  ca$ ~- z* F9 z$ @" {
  setup-globals% ]+ ?$ ]. _; }- E& E1 u- |+ a

7 m' A$ m$ O8 X5 S+ A  ;; First we ask the patches to draw themselves and set up a few variables( c- o( u  x# N( }4 o5 P+ q7 a( O9 G; k/ T* f
  setup-patches9 H  w, ?; e7 W6 i1 I0 y
  make-current one-of intersections% f8 V( O, q0 g8 p% C9 ~
  label-current3 v% x" K# G5 I3 A" E
8 t# g2 H' e# c$ t. o
  set-default-shape turtles "car"
2 Z% V" U* ], q9 v! L+ k: U4 ~- K5 \" @* W# Y
  if (num-cars > count roads)  L- u* q! {! Y& L% Z
  [5 P6 P  r, A6 o6 b$ z( _3 g. p
    user-message (word "There are too many cars for the amount of "
5 K% `4 e/ G6 r) J# e                       "road.  Either increase the amount of roads ": x2 b; u/ {  N8 _( E
                       "by increasing the GRID-SIZE-X or "3 T# h$ O$ d( Z  P9 Q/ f7 o
                       "GRID-SIZE-Y sliders, or decrease the "
, t* l, d9 n1 |1 U                       "number of cars by lowering the NUMBER slider.\n"& t5 T+ M# m' n# d
                       "The setup has stopped.")0 R' A2 I. W! h
    stop4 U: t; _+ f  L
  ]0 C  s1 E1 T+ r( X8 J* c/ t0 L- _
" ?& \/ j( _" [& _) E8 s5 J) @3 Z
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
  n/ n! O, _5 k9 U- F, l$ u2 Z  crt num-cars8 _9 R: t# f* W" O( T+ T
  [
& j3 o$ F6 _" z8 U; I" E    setup-cars4 ~% v* W0 f- P( b. {% b& v  A4 ]
    set-car-color7 d5 l8 e% `- i
    record-data
% Z; |- q( g* x  ]
1 n2 d8 E7 z% P& f7 a/ ?* S
; M% v6 x/ u. s4 l8 P4 U  ;; give the turtles an initial speed1 R0 G* K  A1 ^5 }( J6 N" B
  ask turtles [ set-car-speed ]
; @' q" W( @" n+ P
3 q% k/ {8 A) ]1 e( y  reset-ticks7 p8 S( |0 X, \. a% H
end
' V3 M0 \3 d/ U* z# I3 j  B! X' D2 y  N3 [
;; Initialize the global variables to appropriate values/ ^& n# D* @2 J
to setup-globals8 a: W, ]' C; w/ }( c4 L# a
  set current-light nobody ;; just for now, since there are no lights yet4 l3 G9 J8 V. h0 @/ v5 {
  set phase 0% ^( C8 f  T! g6 _- d
  set num-cars-stopped 0" c7 S3 B7 L- }0 p4 ^2 x1 \
  set grid-x-inc world-width / grid-size-x
  B( B$ h0 n0 j. o0 V1 K! f2 [  a  set grid-y-inc world-height / grid-size-y9 X9 _$ ^3 ?% g% j' y7 S

5 h) l# t( E, R7 P5 E( W. D+ y  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ e5 b% C' T7 g, w0 ?  set acceleration 0.099
" H6 v2 k8 l) p) [9 Kend' Z) y$ @, [* U

7 A: Z& f5 C4 z" B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  a% j8 K( u8 J+ @;; and initialize the traffic lights to one setting
2 O% B+ M2 S# m, s7 ]4 c! pto setup-patches" e. z# Q9 H- c3 g; X! S  T# Y
  ;; initialize the patch-owned variables and color the patches to a base-color4 E/ K4 t. |. D/ @6 l5 ]0 N
  ask patches3 R/ K; w9 }/ R2 P) T
  [& O  ]& P  u# W4 ?7 k
    set intersection? false
6 K# r; S) e, M" U9 e    set auto? false( e, F9 ~" ^4 S* y! R" `
    set green-light-up? true$ ^9 a* o5 T8 z5 a7 ^( ^1 v* {
    set my-row -14 I* y7 `+ [5 y3 m) G7 m3 d
    set my-column -16 n( j/ S6 f& |& ^5 @% r! Q
    set my-phase -1/ J# _  B- n3 Z) c% d' k; R
    set pcolor brown + 3* g4 s) C8 t& p9 w
  ]) J/ Q- {# g$ ]: ]. P! e0 u$ }
; ^9 T" m% v4 V
  ;; initialize the global variables that hold patch agentsets/ U6 u3 l  v' B2 A
  set roads patches with$ ]9 m0 ]( E5 S' X% |
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or/ K, u% r( H! k$ C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 g9 ^0 F* D) p
  set intersections roads with
& q+ d: i/ X" P/ m( f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
- R( [1 e* ?* c3 b% r# T- c    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 R- ~5 C, h# ]
" w& |4 q' _% U8 F  ask roads [ set pcolor white ]
! @$ L+ X0 [% b3 H$ a9 U    setup-intersections4 z; P  u9 S0 L7 E. c
end9 z6 ~& [. c3 E# T
其中定义道路的句子,如下所示,是什么意思啊?
2 a6 O( C" k, y set roads patches with+ O- A% U! K/ W! w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or3 ~0 J, j/ D, L% U' w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 N/ M2 q! y! k# s
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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