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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。( H7 u. U. A7 \% T( `
netlogo自带的social science--traffic grid这一例子当中,
5 w8 Z8 R" N$ v8 x0 Uglobals
2 \' C, ~( F8 e+ ~[
! P8 q2 l" t) ^$ L* Y  grid-x-inc               ;; the amount of patches in between two roads in the x direction( C" B4 S! ]5 k2 N
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
' b5 S( g- `* C8 T  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
2 C) P9 x0 v2 K9 C0 Z; ^                           ;; it is to accelerate or decelerate
  v( T& d1 J( }4 z, N0 m7 H  phase                    ;; keeps track of the phase
: m/ ~1 ^! A7 Y* |, W9 C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) G0 O5 ?' u( V- Y- A
  current-light            ;; the currently selected light, E+ F( ?  x1 ^- c+ }! P# o% w/ {
$ P6 k3 H/ f0 k8 [
  ;; patch agentsets7 U9 w% E, d* g6 x
  intersections ;; agentset containing the patches that are intersections9 v9 j7 v  R0 O0 B9 o
  roads         ;; agentset containing the patches that are roads
2 s& r; M7 D  ?; t/ Q4 k" g, j]
4 x: f4 B+ _) m/ C1 }0 }3 P( w
turtles-own
: b* D9 a9 P9 J8 E[
0 i8 l( G) d6 w8 [( k) \  speed     ;; the speed of the turtle
  ]" b/ Q% ^. |/ l. Y5 r! a  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
+ Q* M1 `3 p* C( w  wait-time ;; the amount of time since the last time a turtle has moved9 j0 g8 \" b2 n2 s( @$ V- q! n% K$ A
]) c- @' t/ T: _- ~% W
, c$ A/ ]# T! y6 N; S
patches-own
, ]+ @% V4 R+ H, w[& y. H9 z6 s+ {& Y# z
  intersection?   ;; true if the patch is at the intersection of two roads
1 f; k/ ?7 b8 t3 L8 \& l  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
. O& J, n9 f/ R9 g$ a! \# |                  ;; false for a non-intersection patches.3 D( J7 m  Y: m6 _2 E/ t
  my-row          ;; the row of the intersection counting from the upper left corner of the
. X& K1 s$ f" `  W' P1 M9 V                  ;; world.  -1 for non-intersection patches.
+ k- p, C0 O) i" h  my-column       ;; the column of the intersection counting from the upper left corner of the
; V, p6 |5 {: R9 R/ Z" J; ~! K( N                  ;; world.  -1 for non-intersection patches.
! r, m" z, _" M& x6 ~  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; {* G/ c: L6 y3 v6 j  auto?           ;; whether or not this intersection will switch automatically.
5 z, b  z5 \5 H$ n                  ;; false for non-intersection patches.# C: k3 w: F% c- \: O. i3 M! _# _
]2 ]& p0 s6 `! @8 G
4 T! ?' _+ }( E; r: k1 H
: r; [4 v8 \+ f3 W8 ]% L
;;;;;;;;;;;;;;;;;;;;;;
* F. U' f* ^6 L;; Setup Procedures ;;
" k, |$ a, \! o8 N; C9 C;;;;;;;;;;;;;;;;;;;;;;  \% v3 x1 w3 Z
* R# T; p% i  [6 I! w( F
;; Initialize the display by giving the global and patch variables initial values.- t$ M6 v9 O* l2 t
;; Create num-cars of turtles if there are enough road patches for one turtle to3 _+ O9 }# V5 q: s3 o, U% d  M
;; be created per road patch. Set up the plots.
0 p' u2 v/ V1 a3 U, |  N- Yto setup- r* U. @# G2 P
  ca
& N- _$ D! a, B8 j! `" G  setup-globals+ v2 d$ Y- x# J' h* Q% ^
& |5 H# w& j1 v
  ;; First we ask the patches to draw themselves and set up a few variables' j, a9 E3 L- r! x$ D) M
  setup-patches5 z" b0 X8 s# Z; o7 R" t
  make-current one-of intersections: G0 u) h, A: k# C6 S. h& H2 W
  label-current
" E7 c& R- X( _* ~4 F
" m( V% v6 a! E" g' ^  set-default-shape turtles "car"
, V# q4 n! I, w7 A
$ ]/ {  g9 I7 J$ n' R2 U5 y- h% M  if (num-cars > count roads)
% o1 X2 ?7 N  e  [
0 F  ?9 q1 A6 [# O8 E4 f    user-message (word "There are too many cars for the amount of "
1 q; R! e0 g% Q+ s                       "road.  Either increase the amount of roads "  ?5 c! d9 l6 k+ p
                       "by increasing the GRID-SIZE-X or "" N- q) ?5 f" f$ e0 [3 O4 E3 l$ c
                       "GRID-SIZE-Y sliders, or decrease the "- C9 L" S& H3 {3 U( ?7 K
                       "number of cars by lowering the NUMBER slider.\n"
; d- A& e3 u3 A  n0 I                       "The setup has stopped.")
2 K) z$ {" F$ i0 W    stop  f. w9 z) c% V& G/ e
  ]+ v6 ~0 Y- m: U! r
) ~) N1 f1 C2 Y5 m1 w. \4 N
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color# T' Y/ B7 X$ j1 C9 s
  crt num-cars8 Z( G. _8 a8 M' u0 }% A4 @9 y
  [
0 x( t) r0 @4 C    setup-cars' e- o" v- }% y% Z
    set-car-color
1 e" V0 j( {$ Z& d- J% v( u) [    record-data
# j  R& ?- i6 m2 ?4 w$ Q" @  ]
. A5 ]5 }. t, w9 I& f3 v
/ J' P7 m4 H1 Q& o9 ^" a  ;; give the turtles an initial speed9 ?' v# I( x; x
  ask turtles [ set-car-speed ]$ g/ E% o3 Y  p- j8 Y

7 H6 [/ C1 z2 R7 H8 B0 H  reset-ticks9 k( v6 x3 k1 q7 U
end
4 b( H- G8 u- H, x! U0 O! `: D+ w3 n$ Z4 n
;; Initialize the global variables to appropriate values
# M( W8 H) T/ B& w$ s% C5 Kto setup-globals
$ M1 l; q# {2 ]* S6 A; X  set current-light nobody ;; just for now, since there are no lights yet+ Q5 Z3 U; l! g; Y; w2 b
  set phase 0
. U  W# u6 B! T* i( l2 z  set num-cars-stopped 0, i3 h6 ~% W$ ?! L) x( S) ?7 v. L, ~
  set grid-x-inc world-width / grid-size-x  y) ^+ t; D9 O$ i$ U
  set grid-y-inc world-height / grid-size-y
, W! l" j* N2 e6 \1 j' A+ M
6 k6 ^. R- \. V* w2 Z3 P% [* ^  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary7 q' K" W) Y* O
  set acceleration 0.099
& k3 S3 u/ L$ p  |. c3 g  Dend
- }2 Y% H2 c3 E6 x% X8 H* \4 l9 Z9 e/ v) J0 }/ t" h
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,% h1 k5 b- z0 j
;; and initialize the traffic lights to one setting
9 a& n, Q0 G2 X( ~5 _+ t+ gto setup-patches
" a( E% P8 R" i; u9 P" e  ;; initialize the patch-owned variables and color the patches to a base-color  G  h- _/ P7 c! M# M
  ask patches
4 r+ S* B; {! o6 d$ S! o2 b: L  [
9 I7 v% F8 W1 c6 b! v    set intersection? false
( ]8 I  E8 m  H8 Y2 }: J    set auto? false  n. e( ?% R6 g, S+ ^, [
    set green-light-up? true2 n4 I: i4 I) r1 J
    set my-row -1
; f+ z  N; \3 X( L    set my-column -17 B4 j8 @/ l5 h( Z
    set my-phase -1- N* X- Z1 B7 a
    set pcolor brown + 3
6 D1 Z8 ^) U6 Z. z7 t/ m  ]
% k* U/ e5 M- b, k' ?5 c5 F% m8 s2 a2 |7 q4 l. f( p
  ;; initialize the global variables that hold patch agentsets9 J7 A( B; o) Y: Z, a
  set roads patches with+ z. C) k: a6 j0 F6 m+ }( x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or: F: X0 c( O. Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ @6 U# ]% ?- n# @; C
  set intersections roads with) L- k; }1 o4 a  o( `* u; X4 ]. n
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. I; I, H: N' P* Z' o# o5 I1 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) N# k' q5 H- ?
+ |! e; M9 ~/ I& @" e2 X+ z$ _  ask roads [ set pcolor white ]
+ H" U$ s3 `3 x, R    setup-intersections
, C& h5 G; C7 a& g* [) tend
, P& ?' {' y9 h3 M  @: X% n其中定义道路的句子,如下所示,是什么意思啊?
: E# K/ g* }" r; X, u set roads patches with
* ^0 E8 @' D: F" K& ?5 v    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  b5 o- Z) S" Y5 a; |# v8 f
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' F0 O4 r( t  V( F9 m$ 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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