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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。3 T) n- |+ b! [. n* r
netlogo自带的social science--traffic grid这一例子当中,6 C7 W. f# |/ i( C! I/ g
globals
$ u# }$ t0 Z* b2 t" ]. d[. `5 a; |& v4 U; O) X) J
  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 n9 s$ E+ Y. N
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
( o1 L9 Z( p1 z1 i+ V0 G  acceleration             ;; the constant that controls how much a car speeds up or slows down by if" o/ V$ G' i0 i
                           ;; it is to accelerate or decelerate
2 ~+ S4 `* F( u' Z9 F  phase                    ;; keeps track of the phase
3 m$ y4 @) H' m( O* g8 c# ~  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure; I; h# |& _+ ?7 W. W
  current-light            ;; the currently selected light
& V' {/ k" `& }5 a' f$ [1 J1 G6 p; ?
  ;; patch agentsets
+ n5 f7 K1 E) H' J, z9 S$ T9 E, l  intersections ;; agentset containing the patches that are intersections7 A4 w  D1 k$ t; W
  roads         ;; agentset containing the patches that are roads9 M! i* B* I5 U+ r5 ]8 t3 a3 j
]9 x* B7 r# g" H  {1 e
/ x$ J3 f3 a9 u5 Q. j& R, T& m0 y
turtles-own
! A. N+ }/ X, ]( j8 v[
7 X. N$ R) X2 a$ k  speed     ;; the speed of the turtle# k* ^# A) Y' |: T
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( {6 V* d. F4 g9 U# l  wait-time ;; the amount of time since the last time a turtle has moved
9 g! L5 q1 e7 y3 v]
7 \" o" R+ E& O3 e2 U( @0 H1 O+ K2 H% F9 G& z* T2 z2 Q: E$ F5 l
patches-own* P- M& Q5 k6 `2 r! M
[4 D1 S/ T! ?5 S+ u+ l
  intersection?   ;; true if the patch is at the intersection of two roads
) H: M5 X6 K/ P+ ~; I* q1 t8 u- T  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 k8 a  t/ q" w  Y/ m                  ;; false for a non-intersection patches.
& T  f# d- z* u  my-row          ;; the row of the intersection counting from the upper left corner of the
. f6 ~3 C( t* \& m# x% }* {                  ;; world.  -1 for non-intersection patches." e7 z% d: R! W' Y- [: v
  my-column       ;; the column of the intersection counting from the upper left corner of the
$ x2 E+ p: ?6 K& T7 Q" }# Z  z$ {                  ;; world.  -1 for non-intersection patches.+ o* s) S5 W! \# k
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" D) ?7 `8 f; v+ p3 @8 o  auto?           ;; whether or not this intersection will switch automatically.+ o5 K* O& q6 B
                  ;; false for non-intersection patches.
# a. g" I5 u1 h6 Y+ R4 C, e$ }]$ O+ x5 F9 S. e5 |
9 N6 ~8 {3 D; ]8 ~5 C' A$ l( {9 _
4 P2 _1 \7 \* }4 J3 Z
;;;;;;;;;;;;;;;;;;;;;;
! w& d* t( ~- }+ w1 C3 u;; Setup Procedures ;;
) z" s" j. f$ S4 B! D8 a% r4 D;;;;;;;;;;;;;;;;;;;;;;2 X$ i. V, s% n8 \( w$ l

4 M5 _6 D; Y& c$ E2 f6 Z  d;; Initialize the display by giving the global and patch variables initial values.9 Z& [, x' N% I- G: G
;; Create num-cars of turtles if there are enough road patches for one turtle to  ?& G! K1 \" |- T, v  V+ L, u' P
;; be created per road patch. Set up the plots.
1 _& J# Q+ j  X; `+ Cto setup8 v' Z7 S( O1 i" S: [- `
  ca
! g& D* z3 t" B1 F! |6 `  setup-globals$ V* q: g6 o- i+ D' u# |

  g; S, X: o  S9 r( }  ;; First we ask the patches to draw themselves and set up a few variables
$ m- F, r% B! x# J6 p0 f1 q+ @& r+ n( o  setup-patches
, z  {# c, b2 b2 b* F( H. \  O  make-current one-of intersections
* y4 i8 [7 ^- k" @6 y  label-current: a0 f% I  }& r/ [. v, M" p" |

0 V% w# c- k$ A8 O  set-default-shape turtles "car"
3 `! `1 |: S7 n; E+ O* z! u5 I* d/ Z" z1 L
  if (num-cars > count roads)8 V, N8 W* v3 V! t
  [
% l/ a; l4 T9 |    user-message (word "There are too many cars for the amount of "8 g) M/ M+ M9 u2 O
                       "road.  Either increase the amount of roads "
2 c' V- V7 i2 q( B4 A- X! c) U4 u! O                       "by increasing the GRID-SIZE-X or ") c. i* b" [2 k( X
                       "GRID-SIZE-Y sliders, or decrease the "
6 J7 I$ H6 z4 r                       "number of cars by lowering the NUMBER slider.\n"
$ C- j- b) ?  v# {, `: K0 j                       "The setup has stopped.")
5 X6 t- c2 W$ C5 U    stop
% u+ q' Y9 F/ U; s. h  ]
3 F1 C3 v! E- w9 s4 P
' X6 B1 v( k$ Z% ~% X1 x' B( I% m  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ v3 h: E0 p6 c6 M# z
  crt num-cars+ V1 I, K; G0 T- c8 u$ Z, o2 P
  [
, P9 @' w9 h* [. Z! s! t    setup-cars
: |; r( E* u$ u2 i3 u/ E- p6 X5 C    set-car-color* ?3 T; J& t6 U' l8 g0 Z+ I, r3 ?
    record-data+ H1 {7 E  h7 q, D
  ]" }# S1 w/ ^0 L  r

( V3 s  m. W- X4 s( Z+ A) o5 m  ;; give the turtles an initial speed! }8 H$ j) r! n' u! |4 o5 M
  ask turtles [ set-car-speed ]
- @* F- s  k4 p0 }( v
3 J' b3 ~: ]8 U  reset-ticks
( O: w& l3 I" {* {" h5 r/ I4 g: lend
  j1 Y/ ]2 B, T0 P; H: a/ c5 O- Z6 y6 [# Q6 X
;; Initialize the global variables to appropriate values+ E% ^  ]* o5 \
to setup-globals
* ^# t+ l! k4 d1 e4 Z5 Q  set current-light nobody ;; just for now, since there are no lights yet
4 c/ _$ o+ b/ I5 f2 g# R- b; E  set phase 0
# G3 r( u* ?; V$ R  A( U, c% ~  set num-cars-stopped 09 I9 s# @: O5 F! S8 Y. d* `
  set grid-x-inc world-width / grid-size-x7 ]* H. w* ^- m# m
  set grid-y-inc world-height / grid-size-y
" u# ]# e0 `; E  N+ l" X# `3 c9 h$ `) ]) L1 L
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary! |; ?0 ~2 P- p
  set acceleration 0.099& o) T7 N% X% f0 @9 p3 g
end
/ R  }) _4 g$ y# x5 T3 g5 j* q* p" c7 ?: D$ R4 L  C; m9 Y
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,0 E! h& E1 g0 u* t1 O. p
;; and initialize the traffic lights to one setting
/ z8 D4 w/ `, ^4 [8 }to setup-patches) g. }3 \0 R( q. F- t0 x8 L. a
  ;; initialize the patch-owned variables and color the patches to a base-color
) v. S' `4 _* \* s  M  ask patches
# y' ^4 |9 _2 k% p  I  [
8 ^) j. N$ D2 T% l5 J    set intersection? false# ~+ N' }5 w2 C  H: X
    set auto? false. U9 h; l0 h+ I( g# l! Q3 l
    set green-light-up? true/ a% |" F; a4 f: C, e/ P
    set my-row -18 ^0 w4 X8 o2 T) h7 T! n
    set my-column -1
- D9 U! F+ B! ?" v* i$ Y* \% z4 g    set my-phase -1
. V( j1 S& Y1 Y2 k6 O2 P    set pcolor brown + 3! r: x+ S3 }, E
  ]
7 _" `6 Y# G) P% w/ T! @7 D: Z8 ~+ C; V5 v6 E3 h
  ;; initialize the global variables that hold patch agentsets
  ]  |- p8 K, H2 u: u# }  set roads patches with
" B' F$ ^( h1 ^) Z5 c' H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
( J! Q6 y( q4 x/ |6 _  D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 T% n9 W7 }5 l/ K$ h5 M7 z8 v
  set intersections roads with  U+ ?( r" d( t* }
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 L: x1 r& }2 o5 D. n    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], u# j! {# }# V- l- @5 x) {% W
/ |! z* k3 ]7 H2 H. P8 |& [) `
  ask roads [ set pcolor white ]
/ i5 I1 P5 b! s: R" y5 r8 |0 N    setup-intersections
% \6 n/ f- S5 L, C- Z( u' C) h1 _end
/ m1 }  ?9 C0 y4 J9 n其中定义道路的句子,如下所示,是什么意思啊?
( R: J8 @7 X: I' w set roads patches with
- `$ E/ F' x& e& r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! ]* u" v8 S% R& o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 P7 g+ Q1 P, b5 ?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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