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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。# ^! ^5 \7 d* T2 O6 E& B+ P
netlogo自带的social science--traffic grid这一例子当中,
# R9 m5 ^( _$ `. b& i( t* zglobals
0 S  g$ {% r# k' w" p+ j[0 W) t, L1 D( W  y5 s+ k5 O  K
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
; Y0 j2 H# ~  F- J) u  grid-y-inc               ;; the amount of patches in between two roads in the y direction
8 O% y" C1 m) z) |  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' S+ `" e6 W/ g9 l# V- t                           ;; it is to accelerate or decelerate' O# d. u: f2 J1 L) P! ~
  phase                    ;; keeps track of the phase
) t& H* F9 b1 x" x: c  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ J  m4 z& D" A: G/ T# |5 c! s( F  current-light            ;; the currently selected light6 @7 x) y6 _% K# s8 `
, i1 W! @& `6 Y( e! ]- f  Z1 R
  ;; patch agentsets
+ A& L6 ]) R9 r  m3 H6 S  intersections ;; agentset containing the patches that are intersections
1 A8 ]$ C  x  V+ V3 v  roads         ;; agentset containing the patches that are roads
$ d8 x! m* k. s6 p7 k; [$ d]
) y, {* z8 p  J5 L) H0 u& q) n+ K) L
turtles-own" r0 S2 u) V9 s4 o$ E5 D4 T; z
[( V' ~$ e* j+ n
  speed     ;; the speed of the turtle
) O5 r: g. w: V  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 L. V6 r2 m/ ]' K- F! @  wait-time ;; the amount of time since the last time a turtle has moved" C( H5 Q6 C& D, T
]
& L# b5 S) ]4 B* X" g" M" F
4 `, L5 U3 E# @) E3 ]patches-own
6 V6 ?  L& N" m4 }: k' F[: [2 _  @0 Y' W- a: y
  intersection?   ;; true if the patch is at the intersection of two roads0 l/ l# Y( P5 Z& ~4 y
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* P, F" u$ ^8 @2 q" J$ x- ?                  ;; false for a non-intersection patches.2 K1 a7 i& K; ~: h0 C5 s
  my-row          ;; the row of the intersection counting from the upper left corner of the% u! x% `" N' \& C0 x- n
                  ;; world.  -1 for non-intersection patches.
4 M0 p$ k/ L8 N) Z2 Z. ]/ D  my-column       ;; the column of the intersection counting from the upper left corner of the
: p9 d; @2 Z. D! b% d0 ~' D, ^                  ;; world.  -1 for non-intersection patches.
, ~5 c0 R9 k3 V4 C+ q/ }  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.- k; \, k& x) n6 y
  auto?           ;; whether or not this intersection will switch automatically.
! a5 [9 b" O) u2 q2 `7 J5 Z                  ;; false for non-intersection patches.
4 ~: X8 [( }/ ~+ Y  [3 C]" M9 h4 c4 C, i0 f% R0 P: p
, s, Y- x& P! w/ v2 R8 w

" O& C$ K3 y9 t;;;;;;;;;;;;;;;;;;;;;;
6 C9 I3 ?0 j; K5 k+ J- _;; Setup Procedures ;;1 w4 P- ~! h/ ~: V% }* E! }, q
;;;;;;;;;;;;;;;;;;;;;;1 H( C) L, R; \
5 @; e$ N$ `! q6 p) ~5 H/ G1 j
;; Initialize the display by giving the global and patch variables initial values.
1 y) h$ X' B; o3 ?;; Create num-cars of turtles if there are enough road patches for one turtle to% n! \4 g/ y9 w7 g5 W! r9 n' J+ |
;; be created per road patch. Set up the plots.
* O0 B+ a5 Z6 z: ^to setup
% U. M8 K# x% I4 c  ca
' L5 b; Y6 ?1 l( [) Z& z6 S  setup-globals
% A' \8 Q. ^7 D( v1 G  J. Y4 }( a1 |8 G0 u: \9 h# _# A! x8 Q
  ;; First we ask the patches to draw themselves and set up a few variables
4 `0 S# V. Y5 O  setup-patches
6 z; z: {6 c$ }+ k+ M  make-current one-of intersections1 X: K% N1 @4 o# K' O' n
  label-current* i6 {9 v: ]  x3 b/ H# Y$ g
+ C1 ^! {1 s& M- x; ]9 v
  set-default-shape turtles "car") L& `) X4 i* ~: W
' ?/ |4 s* m  U. S; P2 m
  if (num-cars > count roads)
2 j# V* r. \: F% q- p! i  [. z- e; ?1 o2 i" D
    user-message (word "There are too many cars for the amount of "" E# g9 s, C' l$ N# G% |
                       "road.  Either increase the amount of roads "8 R' h: s/ ?# ]
                       "by increasing the GRID-SIZE-X or "/ u) h/ ]; Q& S+ ^1 N# t+ V. s1 y+ r
                       "GRID-SIZE-Y sliders, or decrease the "
6 m& g4 _  h+ T( {- ~, @- @                       "number of cars by lowering the NUMBER slider.\n"
& W: [: o7 R' W- Z                       "The setup has stopped.")
& b" U% a% f9 g$ w( @. R/ X! S( w    stop
! r, P# U3 y( w$ c* t  ]
9 |4 `- ^9 v  p; s2 N# |( [6 c& h. w! n1 G
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
" x* ]) V) O" @+ `, j' n  crt num-cars
! F# c! q' {% {; X- m6 r  [4 L* K5 p/ ^' n
    setup-cars8 `6 u  K7 I: E+ s
    set-car-color9 Y7 ?! O8 s- }, ]
    record-data
) ?8 L0 T7 ]! O$ ]% R; S4 r% H. c  ]: C& |' Q! o8 \% C$ |
$ x( V$ u# E$ h4 B! S
  ;; give the turtles an initial speed; x5 V! b5 E- T3 f5 E! F. ]1 T
  ask turtles [ set-car-speed ]
- ~5 ~/ r4 \3 [3 ~9 P" n4 d: @8 i( k3 G( {2 s+ I
  reset-ticks
7 D, `6 d0 H9 w! z' aend
+ K% z( s9 h" ]" P! Y- |
0 S7 ?. g4 B, d" L6 @;; Initialize the global variables to appropriate values
/ l7 o! e/ R+ Z. J0 O# Rto setup-globals
+ A" _2 L- X0 _# s  set current-light nobody ;; just for now, since there are no lights yet
& ]' R4 A0 O- \) k$ I% @1 b3 W  set phase 0% W% E9 S( F/ z  \) V$ J7 H
  set num-cars-stopped 0! j* Z9 N# c6 w0 b
  set grid-x-inc world-width / grid-size-x7 g$ b# P2 v$ h1 x, _/ a
  set grid-y-inc world-height / grid-size-y
- d# p* K% G2 v( y2 o) L5 v9 j5 h2 D- V/ V
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! [' I1 Z/ J+ @4 E& p  set acceleration 0.0995 |6 V3 K8 z" J+ b# q8 z
end
: p( D8 n/ l, D8 t+ W* S. x" Y% T
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,9 ]7 ]1 X/ V- b- t3 k
;; and initialize the traffic lights to one setting3 F# w5 l! H1 X1 R+ G) h
to setup-patches
5 r7 \8 I1 x$ |: k4 f5 H5 {+ y  ;; initialize the patch-owned variables and color the patches to a base-color
8 H5 t% K. ^/ e; l0 V  ask patches6 ^, }9 R3 |& r" f/ X$ T
  [; J( Y6 o- H6 a1 j  j% R
    set intersection? false
9 A% S( }' J  w6 ]( o* y0 O! P+ b    set auto? false' c% ]" E+ L2 D
    set green-light-up? true2 }$ f% b1 A7 F6 V
    set my-row -1
. U3 U5 Z3 `' R% U* n7 |    set my-column -1% J1 {% X. U( R9 P
    set my-phase -1
2 }, A& y) Z- k$ s* Y) u8 ?    set pcolor brown + 3) q. C! }  k- |/ h2 }% P
  ]
3 v+ N) @! _2 s' \4 ?0 K$ w8 `6 {4 l7 {% \2 L0 O  u
  ;; initialize the global variables that hold patch agentsets- s% q: d9 R1 E; q! S7 W
  set roads patches with
. w4 ]. s' H$ h/ J    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 _; E6 @: _! f' g$ _" ^
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, v& L% J( ?% Z! }; |! Z; i  set intersections roads with
; s* R+ ^# P6 K8 {0 w2 g    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
5 P/ U4 P1 P. F2 f8 R    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; i9 Y" \* w: v& G# @1 E7 X" B8 Z: x1 B6 H0 t9 _
  ask roads [ set pcolor white ]
' ~' ?; h* S7 f" v    setup-intersections! E. \! X) j9 o9 F
end! V- q7 Z! O* z
其中定义道路的句子,如下所示,是什么意思啊?. g, j7 T* f8 ^' z
set roads patches with
) n5 B6 ~9 t) B% r5 d) T. p, D    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 u8 J; S0 _& C7 t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ w1 E/ L$ A% W# S5 E5 G
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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