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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 U( W( j4 L$ @) Y" z. S+ S$ Y
netlogo自带的social science--traffic grid这一例子当中,8 _6 }' G( S3 R
globals" P; A3 ]  v& r8 j
[
5 P2 n( B+ u5 }9 [  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 ~: @4 G2 T# b( h. O1 {; g  grid-y-inc               ;; the amount of patches in between two roads in the y direction& s  x0 g+ M2 c/ q; s
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if& w+ N" B2 [5 D5 o# |% _. t, V
                           ;; it is to accelerate or decelerate
+ V, l) l4 \) C; C" v( T  phase                    ;; keeps track of the phase
, ?  w6 ^" v8 F) q: `  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) K, b* `: ^/ M; I8 m
  current-light            ;; the currently selected light
" H4 n) _; k8 x/ }5 Z# ^- E" z; c1 |
  ;; patch agentsets# _# l1 z1 Q! `
  intersections ;; agentset containing the patches that are intersections
" V( a" n. Y" h# Y5 u7 s9 X  roads         ;; agentset containing the patches that are roads, V; j# c4 X& c6 ^1 F4 |2 x
]3 I1 m8 f  I& u$ O: J2 N+ V4 `
; h8 X; k, T& C
turtles-own, x) X2 B7 q4 p/ H& e6 }% A
[
4 {9 U* o  R+ q0 d3 r  speed     ;; the speed of the turtle5 `3 N/ ^. l' l, a& g% l% U
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( r" j5 i+ s9 T  f) g+ L  wait-time ;; the amount of time since the last time a turtle has moved
5 b) `3 J6 q4 P7 U% k7 C]+ m& I: ~1 O- J3 }/ w) ~

- k+ U8 f4 q( fpatches-own( ]% [) z2 M2 m5 n! j# N
[  \1 K. o2 v0 r# E" C) `. I# G# q
  intersection?   ;; true if the patch is at the intersection of two roads8 ?9 K, a8 f  Q3 F/ U
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.: E# q5 w& m: g. M; g5 L* n
                  ;; false for a non-intersection patches.
2 ^$ w& J2 \: J) r0 P  my-row          ;; the row of the intersection counting from the upper left corner of the- s& u; w: L$ p+ N
                  ;; world.  -1 for non-intersection patches.
* }1 b" ]- f# d* F# U2 _& q+ A  my-column       ;; the column of the intersection counting from the upper left corner of the) l2 k8 p1 g: t# v: Z8 Q5 z
                  ;; world.  -1 for non-intersection patches.9 Y( j( m' Q7 ?
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.! `2 @: i) h  N, ^
  auto?           ;; whether or not this intersection will switch automatically.6 i* ?- R/ _0 O! j9 C4 Q
                  ;; false for non-intersection patches.; L" K! ~4 v2 |6 m
]# A/ n/ t3 ?; l

" x6 J$ H0 P4 g) a9 q8 y/ b
% E" P  T0 L9 B- @3 D- k% o;;;;;;;;;;;;;;;;;;;;;;$ Y9 h& g4 a" {9 k& |6 u
;; Setup Procedures ;;
4 m  K: q8 `* J, v  g& l8 I;;;;;;;;;;;;;;;;;;;;;;2 o" b6 ~. l" w* b3 R/ q
6 Z4 N' \" n8 O7 v
;; Initialize the display by giving the global and patch variables initial values.
4 i0 {+ {+ u. a/ T  x1 m3 `;; Create num-cars of turtles if there are enough road patches for one turtle to8 b% R( e+ w; H" f( _$ d
;; be created per road patch. Set up the plots.2 R, j# l8 I* F/ N; i; W1 Q3 P. N
to setup6 K6 ]- R) @& k" v' S! X6 U* X
  ca
) ~2 J: H) O$ `  setup-globals5 M% r! |( @6 a, b& c9 p  m1 W
+ [( J' Q/ V  x8 k
  ;; First we ask the patches to draw themselves and set up a few variables  B: q" i7 w9 g6 v" p$ Y5 V7 Q
  setup-patches
  K! n5 l" l% t/ a7 M  make-current one-of intersections
# R% e2 _5 b$ A5 W2 O1 U5 C  label-current
9 ]; G" |, e! c4 J& `! G6 j" K8 v1 C/ r/ h1 x1 P1 Z
  set-default-shape turtles "car"
; ~8 h, ^; z! z8 E
, H+ }2 g5 T. f1 u4 u$ T. F3 |  if (num-cars > count roads)* W; _$ t9 s0 c2 q5 r0 E) R
  [( V# y9 C8 d6 a/ q5 @1 z
    user-message (word "There are too many cars for the amount of "
9 q& c& N+ I# ]6 e' R- h- N8 l( V                       "road.  Either increase the amount of roads "
! W& j" Z% ]% U+ v$ k                       "by increasing the GRID-SIZE-X or "+ Q8 C% t5 j" r0 A' M
                       "GRID-SIZE-Y sliders, or decrease the ". P0 k: u' j, f- d1 \
                       "number of cars by lowering the NUMBER slider.\n"5 ]: y# K' n7 O: ?1 a- _0 d6 ]
                       "The setup has stopped.")5 v, I4 u8 z5 g
    stop$ E- ^! `5 H' ~8 B- w
  ]8 Z1 l3 Q' b. S1 n! H$ s* i* Z

( m9 u9 v( X# Y/ \/ ?& c  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
5 O2 N  b, S4 K7 @( m  crt num-cars- ?& Q" V0 j/ v  p# i8 e
  [; M9 [5 u  J5 D& S% n' G7 h4 m
    setup-cars; Y  m# H, _2 A; A0 y
    set-car-color
1 D0 ~& i  h) g. Y& W8 D' E    record-data7 m5 b  Y* `9 T& w' O0 t+ S
  ]
" M9 }$ H3 e% S1 b3 b/ Q6 K# F3 H' O9 g
  ;; give the turtles an initial speed& V6 V4 b2 I- {' b
  ask turtles [ set-car-speed ]
! K/ _) V  R. \, T0 y1 _# B  B
2 R% z9 X4 Q( P/ q5 a: E2 ^  reset-ticks
  G9 y  c+ ]5 j& e1 Oend6 e3 E$ b8 R6 q" z- i  E4 ?( d

( E/ c2 d6 I& @;; Initialize the global variables to appropriate values
  C  W! S. k4 Nto setup-globals
& @2 w: l2 B2 ~/ e: |/ W1 p# T% J  set current-light nobody ;; just for now, since there are no lights yet$ I; a3 C( b, G1 X4 H
  set phase 0- |3 P7 X4 r' O% G- V% l6 `
  set num-cars-stopped 0
) J+ ~. W. g7 _) x  set grid-x-inc world-width / grid-size-x
- f% ?9 o5 u& Q2 Y+ @+ w  set grid-y-inc world-height / grid-size-y
  o/ N: }9 K% i" P  ?2 P
" p* E7 q/ d% q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary- k9 r! r! O5 X! W# r0 k4 ], p
  set acceleration 0.099
# y5 d+ v" d- q, W( x% j3 q5 kend
$ ~9 a2 f0 A; k9 E
4 b& ?" W8 I$ a+ u0 c! b;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
" `0 e; F* @9 R1 [/ E3 e( X5 m;; and initialize the traffic lights to one setting$ y+ G" a4 Y) V  j# Z( t: t
to setup-patches
6 [* ]( D9 \+ N+ ^: W! d  ;; initialize the patch-owned variables and color the patches to a base-color7 K. B9 J/ Q) l5 f4 v) G6 g
  ask patches. j# ?% v: a2 [: O0 o
  [
# G5 ?! i8 b6 Q! L0 _7 k    set intersection? false  s& q$ g$ p1 {9 s: C$ E; {
    set auto? false
. P- g2 b+ w% X    set green-light-up? true8 e2 W6 Q5 u& s  N0 w
    set my-row -13 L! L4 U$ u9 ?. i
    set my-column -1( j4 q6 j7 `; m9 x, h
    set my-phase -1, n0 L- R3 l% S% j
    set pcolor brown + 3
4 [( C+ H" A% ?# e% k, n  ]" k) |+ U$ w1 h: x4 x, b

& P/ y1 f7 }! Y8 c6 K; q  ;; initialize the global variables that hold patch agentsets: ]' n! R- I' X5 _
  set roads patches with
: P( _& F9 V' ~* g( F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or. S, M$ l3 _3 w; z) Z, o& e5 b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& ^) t0 ^9 g% E; I- L0 j& r' l  set intersections roads with
2 s: J9 o& y  ?) l7 F    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and8 V  R. f; ~9 Q( C2 A: m- O4 ~
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]! L/ k0 S6 }8 J! F% d( ?9 S! `
! o+ ~/ B- e0 M8 |' V$ R" ^/ {2 G3 e
  ask roads [ set pcolor white ]
8 N# \& b9 ?7 e    setup-intersections
8 g: C/ e3 ~9 A' D/ p0 k) O" iend# ~' ~; v4 g5 V' T- h; d
其中定义道路的句子,如下所示,是什么意思啊?6 R. u9 j# ?; K3 x- x! O: ]8 V. T
set roads patches with: n/ |1 X- Z/ C: b: C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or! ]. T8 U* r2 \1 {7 g. o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 B' m' h. Y0 H# P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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