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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 H& v' K0 [' [1 [$ Bnetlogo自带的social science--traffic grid这一例子当中,
& H, k& t) D  P3 I  K1 ]; pglobals9 D4 k" w" q0 a8 v0 ^3 j
[
- z+ Z( z7 D/ y0 G1 Y7 b  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 ?/ i# E7 K. r0 f
  grid-y-inc               ;; the amount of patches in between two roads in the y direction2 f5 R7 Q+ j9 F6 J( c/ `4 ^
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if: V+ |2 f/ V$ o" l$ D1 J
                           ;; it is to accelerate or decelerate
( V1 \5 b( J5 `  phase                    ;; keeps track of the phase6 J* i0 w( o/ ^1 j' @$ |9 N" e) s, f* K
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure3 T% u: p6 V: t4 A+ C
  current-light            ;; the currently selected light
: b/ u% z8 @: c; ^" w( w/ ^: t
" T$ `3 F8 L" ]& F) {' U  ;; patch agentsets
& W% p# `1 E" J+ }5 x  intersections ;; agentset containing the patches that are intersections
8 p. i1 y$ E& [, R2 [  roads         ;; agentset containing the patches that are roads
3 g0 i1 B4 m$ o& G1 e9 l; E) ~% u" p]
: O9 `% C' M3 t/ h7 Y! O' V' B: }; o$ Z
turtles-own* W; l! k$ D! W
[( H( T8 [: o5 B$ G4 n
  speed     ;; the speed of the turtle4 ~1 r: x9 E2 Z% n$ G- C# A
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right6 [8 O8 Y! q. A& m: R' x, ^
  wait-time ;; the amount of time since the last time a turtle has moved; n( X6 X. U! |  D; f* b4 N! s& h
]
; D! i0 L3 R% D* q, D' b& t3 E" E( \2 `/ E9 ^
patches-own% G# D# H8 x7 E$ o) p$ K% L' d
[
+ U& m5 N& }* F  intersection?   ;; true if the patch is at the intersection of two roads
3 z3 ~1 k5 @. v7 Z  J8 k- A* \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false." O# N3 B+ x2 i9 J  p/ m' q) F
                  ;; false for a non-intersection patches.
/ A3 ?1 A& _: e3 |- t  `% a  my-row          ;; the row of the intersection counting from the upper left corner of the, I% u  V- z( s/ k( W0 y
                  ;; world.  -1 for non-intersection patches.6 I7 G$ v, p$ R& v( _& r9 _
  my-column       ;; the column of the intersection counting from the upper left corner of the
$ Z+ r5 |( ^1 B7 @; d' m                  ;; world.  -1 for non-intersection patches.$ e; t( k8 y( O4 t( h) d
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.3 h" [& m) G8 B3 J" Z) }* x8 {! u
  auto?           ;; whether or not this intersection will switch automatically.
0 i* x% J, r+ x! b                  ;; false for non-intersection patches.
$ V0 Z( y. B2 i: n]
# f# J& ]4 v# v! _5 |# [0 n$ Q. T% n2 T5 A# G
' [7 A/ ?. O7 j2 r) a$ ?5 G
;;;;;;;;;;;;;;;;;;;;;;* ~; p1 \: r* @; d6 b, _
;; Setup Procedures ;;
- w6 y. j& ?1 N' z2 R+ f;;;;;;;;;;;;;;;;;;;;;;) K; W2 w% X- [9 Z

. c8 r8 L7 D$ B2 d+ h;; Initialize the display by giving the global and patch variables initial values.
2 N7 w, n4 {' O# e6 k/ W;; Create num-cars of turtles if there are enough road patches for one turtle to" R5 ~( [  K" X' j  z$ p# N
;; be created per road patch. Set up the plots.% L& B9 L' r  V
to setup
2 Y7 K8 X/ K2 h- Z6 l$ w8 i( `) n: ?  ca
) s. j8 |" N% u" [1 A  setup-globals1 o  ~7 N$ ~- v, q2 ]8 `5 Q
9 ^0 u9 }% b1 Y/ _
  ;; First we ask the patches to draw themselves and set up a few variables
0 I2 Q7 u4 L6 q$ G2 T  setup-patches# I/ |  N2 j" G5 V! @' M3 q
  make-current one-of intersections
3 a0 n8 ?+ B& r# Q3 w  label-current; }3 t- k3 o1 ^$ L* h& a7 Y  y
3 D: Q# P; H' }' h/ a! ]! P5 f
  set-default-shape turtles "car"
) R9 s, P8 j& f/ k
5 K2 ^% m) k1 W+ ?4 }  if (num-cars > count roads)
3 J$ B$ G* T. s& G; h  [5 d6 T7 a; R  b0 Q; z
    user-message (word "There are too many cars for the amount of "0 R7 [$ w, s& g5 V1 A& ?
                       "road.  Either increase the amount of roads "
& \# U  j0 y$ E! R2 M                       "by increasing the GRID-SIZE-X or "& g3 v6 C1 o2 g5 y7 b
                       "GRID-SIZE-Y sliders, or decrease the ": B6 M2 f* h+ `% ?7 e
                       "number of cars by lowering the NUMBER slider.\n"7 U* Z% C) G5 }2 p/ v$ k& Q# `
                       "The setup has stopped.")* B; H1 J; M4 ^$ k3 Y1 q  ~
    stop
  u) k. i8 t; `2 P/ B0 J* }* N+ b! s  ]
" _( n$ d3 ?% L! `7 L, J% `3 T) ]" N, O
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
+ ?/ Y& j( k4 B  crt num-cars, q/ R3 y7 C# ?2 H* g
  [
+ K1 M( P1 s4 c7 K: C% e+ u. p    setup-cars- T2 P/ J: V$ Y1 b  {6 b
    set-car-color) i# T8 o- t  F( U
    record-data: u) ~3 B" |, L- F1 u# J( H
  ]
& Y6 e  W7 r" E. y5 I" ^7 _( o
+ [2 q; P4 Y/ c) h( z9 A4 `: j  ;; give the turtles an initial speed
; S2 q" o* s2 R( l  ask turtles [ set-car-speed ]  s, r- x+ m% T* Q9 S' F( y" T7 n

% b+ I. @& K2 H3 K  reset-ticks
  t$ j7 k6 {& tend  e" |0 ?) K* p& d. L) s1 O3 N

( J# e. x: S4 T3 I;; Initialize the global variables to appropriate values' @! B3 }: b" N) ^8 [6 x
to setup-globals2 e% x6 k6 X6 K( C7 L
  set current-light nobody ;; just for now, since there are no lights yet! b4 a! P" p1 R/ i: M, e1 x
  set phase 0
( Y7 s% M1 y' |& _, i' [  set num-cars-stopped 0! B- d* s* Q0 O2 M" ~5 V
  set grid-x-inc world-width / grid-size-x5 i! Z1 n9 R8 K  ?
  set grid-y-inc world-height / grid-size-y
4 j( e. R) w9 z- C7 t! o! `, ]$ i, d! a+ ^7 ?6 L$ e
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& u& b2 n$ D9 b( C  set acceleration 0.099
0 x3 J' F. s5 b" Iend
, F( U* w* O( V! {, f# @" I+ t
& z1 U2 |7 g6 E( ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,
% B/ v/ o& I6 H0 n;; and initialize the traffic lights to one setting
8 J7 W4 c) ?7 U, w+ a! x% G, a* Ato setup-patches2 O0 A& M: ]% N: g& l% S# Q6 `3 H
  ;; initialize the patch-owned variables and color the patches to a base-color3 ~! E0 e1 l7 q# ?
  ask patches& w- j2 K3 W, [4 Y  x
  [( A( _& @# G4 B' i
    set intersection? false
! a/ F  J# m3 B& U1 v$ u    set auto? false
0 E$ u6 h5 B! G    set green-light-up? true2 w* a) q7 _, g- u2 m- O  i/ N. D
    set my-row -1
6 s7 g. f; R8 z* U    set my-column -1
+ O* u; Y4 `* ]. Q  k    set my-phase -1
4 r, s  V) q: d- E9 c    set pcolor brown + 3" n: D4 M: q7 k+ w/ ~
  ]0 y2 b! F# r! e
8 c. P6 ^/ D% P, d$ x
  ;; initialize the global variables that hold patch agentsets( J% V, i8 G( b3 g. @
  set roads patches with! q0 U; i& N4 c. i# t" W
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! L% Q( H! M1 [- k6 A+ O% b( I# D* I( D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( H6 l0 r' [4 L0 G+ P3 f
  set intersections roads with3 m$ H3 A0 p5 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
* J2 F% u( z& ^( \$ V+ E8 D- \    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 D8 h1 _. ~- E( X# W  A/ A5 ?0 h/ ?1 g+ |( E
  ask roads [ set pcolor white ], w, R$ l& u2 K. n
    setup-intersections- Y8 i9 z5 I7 Y9 m
end, B5 ?, K8 s1 L2 R
其中定义道路的句子,如下所示,是什么意思啊?
. ]  B' s( H& m$ s, _- Z: O set roads patches with
: |$ C8 _! q9 C  L! [. q* [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or  o" J+ Q2 L% J0 ~3 E
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ c8 t- @+ u) {% @. ?
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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