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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。
1 y1 M& c2 A& gnetlogo自带的social science--traffic grid这一例子当中,2 U4 g* O1 {1 q' n
globals
( i  ?8 P. N; r, @7 k# |[
4 b# D% b9 C* ^- U# Q8 B  F  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 L; {' f' l2 K( w- z& c% W( L2 ^  grid-y-inc               ;; the amount of patches in between two roads in the y direction
; y) C. M/ P+ c& o  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
( Y  l; x+ L0 {" U3 h                           ;; it is to accelerate or decelerate0 r+ K# d% u' A# P' L& |
  phase                    ;; keeps track of the phase3 b* F# s) a2 [2 [3 u
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: @1 v9 T) f/ y. a% o" b
  current-light            ;; the currently selected light
- L8 W! L: i2 T& l
& X& L( i9 ?% J# U& A8 {" l2 H  ;; patch agentsets
! n4 j% I4 M7 Z  ~! ?1 M  intersections ;; agentset containing the patches that are intersections3 s. i; w( |  V( p+ O, j( k
  roads         ;; agentset containing the patches that are roads
! j6 L' Y& R3 I3 B3 @% e]+ k4 H- Z" U7 c: c9 J: X/ `
9 V6 a! b: n" w7 W, m1 k9 P+ Y
turtles-own  T: m" f* X" V2 N1 f. J
[
5 G' M- L. U( N3 Z( G  speed     ;; the speed of the turtle
; h* G) x. S/ I4 x! R  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 y- s) P3 h6 j  R& Z  wait-time ;; the amount of time since the last time a turtle has moved5 n* ]! Z) M7 g9 q5 @
]
' l' E% [0 _! @+ M: Y# R# B+ u7 V# F) i1 Y- e% |2 g
patches-own
  c" I- V0 ]9 ^9 i  q3 ][
; n/ Q6 b, k( R# ^# ?. |9 }  intersection?   ;; true if the patch is at the intersection of two roads
. b( y/ j3 z! [& g. _2 b  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.$ p/ u$ ]. Y+ Z3 R8 o5 F; Y
                  ;; false for a non-intersection patches.
& C3 V; L/ q. d# K# T  my-row          ;; the row of the intersection counting from the upper left corner of the
) x1 @. q! }* [# ~% l6 D                  ;; world.  -1 for non-intersection patches.2 N  ~! K! g" t; a- y$ [- l
  my-column       ;; the column of the intersection counting from the upper left corner of the5 m8 o+ `0 s& [3 C& e7 h5 i
                  ;; world.  -1 for non-intersection patches.0 ]! n! ~6 I: b9 X
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.( b( r, B" f; M+ e
  auto?           ;; whether or not this intersection will switch automatically.
) l) t6 A* c, z3 K- P' [( k                  ;; false for non-intersection patches.' T5 H* ]7 `9 |6 t/ \
]! W2 T- x7 l+ Q# |
7 h+ S4 L% N9 ^0 L4 B1 @$ w# Z
9 S0 ]& F2 V3 P! R
;;;;;;;;;;;;;;;;;;;;;;
" m7 [4 f' q( q0 T1 {5 H;; Setup Procedures ;;
% D0 [% L! U. G. L7 D5 [& M;;;;;;;;;;;;;;;;;;;;;;: c  p; [2 F( k$ G
$ U  s4 o: p! G! X9 J! U8 q
;; Initialize the display by giving the global and patch variables initial values.
/ u3 E( s: ^$ Y( i6 G( U7 L;; Create num-cars of turtles if there are enough road patches for one turtle to
6 m+ m) E, o, m9 E( M1 C;; be created per road patch. Set up the plots.
# l" F+ b2 ]8 B+ ^, e1 O0 K1 }to setup  Y/ \4 Z5 n% C! l( I: j2 F" V; j+ q
  ca
9 L- ?4 [, b% m5 q! o+ O" j  setup-globals! q' C. X0 |: {/ J( x

8 t( b$ A( y0 F7 `& `  ;; First we ask the patches to draw themselves and set up a few variables) k: ?- D! y  _2 w  \* O
  setup-patches
8 f. S, I' I+ o) ~$ ?$ s) B. q  make-current one-of intersections& m: R3 L' K( W1 H
  label-current
, ~+ q. ]) h) K1 A1 o5 O5 i. u0 `2 [6 w% c" E7 T# a0 U
  set-default-shape turtles "car"
2 C+ G/ d7 Q8 _# ^4 _/ |$ Q0 L, C
+ L. V' U  e: T  if (num-cars > count roads)
7 n+ {& s# r, q/ {; t* @  [
  x  M' }, N4 M; [4 c; W0 f    user-message (word "There are too many cars for the amount of ". Q% j, [) b# y3 {. C! r- j- g' z' |
                       "road.  Either increase the amount of roads "$ E7 Q+ g/ O- {  n/ L
                       "by increasing the GRID-SIZE-X or ": P* P3 r$ w) X& m2 r: [8 Z7 R
                       "GRID-SIZE-Y sliders, or decrease the "
4 U5 [  T5 ^" Z8 K5 I; j                       "number of cars by lowering the NUMBER slider.\n"
0 M, n8 N4 U% K& O1 d- o" p5 ^. h                       "The setup has stopped.")
3 K4 r6 ~  a  P1 o3 b    stop: V/ S0 X( N% Q
  ]
5 f# X) U/ g4 q0 ~3 V  k9 X; w$ _
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color0 Y; u/ x8 l' I& s0 J& a9 s
  crt num-cars; Q7 h# N8 O& ?7 \3 w
  [
$ `( J. ?" _. N, l    setup-cars2 z9 J( c+ }6 U% R
    set-car-color1 b  I  j6 c# w: E
    record-data
7 }, T3 I) A5 l  ]
' k, G7 W2 ?+ d0 |% P. d7 q) o& e$ N# F7 v! R/ n
  ;; give the turtles an initial speed
, R7 N/ @3 Z( |/ U  ask turtles [ set-car-speed ]
2 o* v( m5 y5 H
" j' I9 A1 B, O' c  reset-ticks
2 D$ [& }( @# x' u( }9 i3 Mend
4 H. J1 e7 t8 Z, R
, x* G( q* f* R- z, P% w% d3 E;; Initialize the global variables to appropriate values( @( J. \+ e6 l! t1 K+ O8 E: I
to setup-globals
/ H3 Q# U% m2 a3 U2 T1 j5 L5 k2 a  set current-light nobody ;; just for now, since there are no lights yet
" h, G# a( S0 s" n: _* x3 G! j8 Y; m  set phase 0
0 L! Q" {3 m3 [3 y$ \: n( x4 P  set num-cars-stopped 0
, H& P' {6 M) r3 J4 @( J  set grid-x-inc world-width / grid-size-x5 u0 x- ^) y8 u
  set grid-y-inc world-height / grid-size-y/ N, L4 e. K  N/ d3 O

: O) w! V% l7 L7 ^2 F  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary, q9 e  F$ P7 o; N7 m; y
  set acceleration 0.099" A- d3 }3 U: e2 H; T0 \
end
4 T  I, m4 k( \7 p  a+ z% F" \; e& z  C* C8 g
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 C! Y) f. u3 ^2 P;; and initialize the traffic lights to one setting
# b) q& `' v+ b& j  R0 E' Jto setup-patches# ~3 A1 K0 [1 m  z1 b4 o
  ;; initialize the patch-owned variables and color the patches to a base-color0 s$ O6 x2 `: Y3 W
  ask patches
! ^6 {% ^. ^2 h$ C1 h9 c  [
( C/ i- i) ^; w% R' S8 O    set intersection? false% W0 q: E$ n) z, E: Q4 r
    set auto? false
0 I* |; @: X- v2 R  R2 s1 V    set green-light-up? true
$ G- h% A! Z% G4 k8 B+ H% J    set my-row -1' n: b  f/ S' k( v
    set my-column -1
" w9 ]: e0 R4 u! o8 O' L5 ?, k- F    set my-phase -1  S0 ?' N3 m. E' q
    set pcolor brown + 3# {, j3 a( i+ S. U$ A' M
  ]
" V( }8 Z' L7 Y4 @  l6 H: u
9 @# v5 n4 J' e& o5 z0 B9 O7 c  ;; initialize the global variables that hold patch agentsets
- ^/ j* a( d7 t$ _/ n  set roads patches with8 h  J) s, C9 x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ k: J( @8 z1 \  k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 |1 S  [& a  o  set intersections roads with' w) J% k( Z4 H7 P9 w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 e2 ]* V" Y6 \! x6 [' I
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
, ~$ j. U+ V; M9 ?5 s- r2 H9 ~5 Q, B
* [  A2 V+ e6 A- D1 ~6 n1 W0 n  ask roads [ set pcolor white ]
, u- F( ]9 C; n: p+ H    setup-intersections
6 F6 S7 }! b' j( tend% o* ~+ }% [9 V
其中定义道路的句子,如下所示,是什么意思啊?
$ H4 ^1 d& M2 K3 i set roads patches with  [5 Z7 z2 @7 G+ k& J8 V
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 d2 M, x2 e% G& I4 A7 H    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 N1 c1 G% R8 B) ~! W: W9 J6 d! Z
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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