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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。8 }; [( j) I2 J5 J
netlogo自带的social science--traffic grid这一例子当中,9 U' C! W+ j  f8 r& |7 W* m
globals
6 @' U! o) L3 U+ o7 v2 A% e2 o[! n3 `4 R1 `" u3 U( J
  grid-x-inc               ;; the amount of patches in between two roads in the x direction8 j! Z/ u% P8 Q) G
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ H* \  K# x% X5 d0 W  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
" c' j1 u9 j. Q& S6 G) G                           ;; it is to accelerate or decelerate
3 C% t1 O- F# N% w  phase                    ;; keeps track of the phase
* n$ i. a* w" t, P+ w  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure' p+ s1 ~  ^, _% o1 ~, S
  current-light            ;; the currently selected light+ D* k: `* n8 m+ s6 T& E3 i: d# z4 S
8 S8 ~7 z: q2 l( U
  ;; patch agentsets
8 o. P3 T  d/ d- X' }1 v, b  intersections ;; agentset containing the patches that are intersections- \8 s% C/ w, ?4 C, J% K8 {
  roads         ;; agentset containing the patches that are roads
0 D* J7 W& U$ e0 M& i2 c( F+ w' []
0 N# R! y1 u  b* u9 \( j- }; Y
' g3 A: `$ Q; R4 \3 Z9 K! s- ^* Xturtles-own( \0 x8 `  G" _3 p9 v$ G0 j
[8 I% s% b! F% U
  speed     ;; the speed of the turtle& Q4 {1 X  L8 X3 ~! q3 I- ^
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
$ R1 G. |2 V) y2 w9 g  wait-time ;; the amount of time since the last time a turtle has moved7 g6 K9 H) x* m! r% y6 r! n8 ]
]
. z1 q6 A* \$ F
' z! n. s1 l& ~  V9 q0 Vpatches-own1 f: h- y$ V6 s" T+ {1 j
[
1 f. i& x1 V( i3 t- u! ^  intersection?   ;; true if the patch is at the intersection of two roads
' ?+ ?# Q/ x, M  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.- b/ z9 @/ v6 S7 x& W! g3 ?
                  ;; false for a non-intersection patches.
$ s8 V( ]# _( ]1 ]' k! Z( Y9 B/ p  my-row          ;; the row of the intersection counting from the upper left corner of the9 E  k* V8 s/ v' g. W. v; t
                  ;; world.  -1 for non-intersection patches.5 i, w  C' Z5 y4 {& L& x
  my-column       ;; the column of the intersection counting from the upper left corner of the
" U8 c5 ^5 b7 ~% |: j                  ;; world.  -1 for non-intersection patches./ m! N0 e, O0 A! V) K0 H6 A
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
* w. d& {  _! [; {  auto?           ;; whether or not this intersection will switch automatically.
! y) ?, T- r2 x+ \) k2 _+ C1 D                  ;; false for non-intersection patches.4 B. \: }8 I) O7 a6 }- ^
]/ T- g" ]5 D3 V% X  q
( ]2 s( j5 o9 ~

( @( O* _) g% L7 n# G& Q0 d;;;;;;;;;;;;;;;;;;;;;;
/ E3 y7 V6 D4 G;; Setup Procedures ;;0 u+ }" v1 e0 j' o2 j, |
;;;;;;;;;;;;;;;;;;;;;;0 J2 k- P, n3 i

* i; a3 c4 f9 A& O+ C;; Initialize the display by giving the global and patch variables initial values.
8 Z2 x2 v3 ?* O0 O8 I0 z  m;; Create num-cars of turtles if there are enough road patches for one turtle to
5 @9 c' `1 N' j6 E  l;; be created per road patch. Set up the plots." V9 `$ T5 S8 |- C8 A* A6 X% ?9 v! s
to setup1 C# w. q- |+ T2 r+ \7 S6 R3 o
  ca2 ?& q) [3 J6 y" K$ d+ M( A5 Z# y% }
  setup-globals
) ~$ ^4 G* x. w. t
! E2 D# {" {/ Y3 j* @& V: ^5 i  ;; First we ask the patches to draw themselves and set up a few variables
; C4 j! d% ?) X1 ^% z0 E  setup-patches
0 r. l& d, B- V  F' N) I% _' a  make-current one-of intersections
! v) d# z3 m+ P& [  label-current5 _' F: I- ~* \- k6 }
* O" L+ j' i4 ^& g8 o( m
  set-default-shape turtles "car"2 m1 r* D+ `) n' ^+ Q3 ?

8 Z8 b- m" c9 v) F$ p  g3 c  if (num-cars > count roads)
  o- j+ S; |( S  [
. o1 V1 M0 N0 o: Y$ o2 H    user-message (word "There are too many cars for the amount of "
/ Q, [2 z& G1 r* [% ~' U+ u1 g                       "road.  Either increase the amount of roads "
. O/ l* @1 T( f$ @" R! l                       "by increasing the GRID-SIZE-X or "
6 V! Q5 Y0 f1 q8 C# a# R+ d                       "GRID-SIZE-Y sliders, or decrease the "
) `$ C5 ?8 _- R+ y. P                       "number of cars by lowering the NUMBER slider.\n"  t6 z8 f; E. ~
                       "The setup has stopped.")
. m3 `. I1 t) e* }& C# p* p    stop7 ]0 {% c2 R2 q- |( I
  ]/ Y! G* @4 }3 Z# q& t9 ~

2 W$ |9 ~0 A+ Q  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color9 Z& f% }, z9 r5 I& y; B
  crt num-cars7 N" n6 B9 W8 C5 D8 E- @
  [
2 H5 m( k  H9 r- E; D    setup-cars
5 S5 g* b7 j+ D' X8 q& x    set-car-color6 p( B1 d7 N' l& ~- R0 d
    record-data
0 K" X8 q5 `" y5 ^+ A, n* @) N  ]# w& Y* z$ }9 C; V! t
% C' f; K$ h8 q6 ?3 U3 c
  ;; give the turtles an initial speed
) ]% S1 j. @3 g( H# _) Y5 S& E  ask turtles [ set-car-speed ]
7 X8 Q( `$ y2 v( t2 ~
4 n- N+ L6 }3 s4 O( b  reset-ticks
: ~& k! T2 P2 r. send
" d8 h+ w5 Q) R2 w. p  @  A0 ^/ U  U. N
;; Initialize the global variables to appropriate values1 p, t5 o; {  s3 C8 Q; s$ f
to setup-globals* h0 E6 |+ q7 W0 S. w
  set current-light nobody ;; just for now, since there are no lights yet6 G9 B/ R' ]& s8 M* k
  set phase 01 R; I) R- I: F# [9 f! V2 \: ?
  set num-cars-stopped 0
: w5 J! E! s) U2 p: G- r( k* z  set grid-x-inc world-width / grid-size-x
  P3 w: d. W2 S0 J  set grid-y-inc world-height / grid-size-y) H2 I8 |' }; T5 C2 G7 j

/ J+ O8 ~1 @8 o  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary1 o: ?$ P6 u. A0 p  d* c0 R
  set acceleration 0.099
# E8 j% N( \+ Y* l1 l# fend
$ W2 @( G6 o5 z4 e, a' s' |" t
  p& Q. z7 }( D) E& R% b7 a, b) u# u; M;; Make the patches have appropriate colors, set up the roads and intersections agentsets,7 o6 f/ E$ u  b$ A
;; and initialize the traffic lights to one setting/ N5 C; p, Q$ d( j$ X& t4 i
to setup-patches
* u- r3 a3 g, b) y  ;; initialize the patch-owned variables and color the patches to a base-color
3 @1 O4 P5 r' G: @: D6 S  ask patches
. j, Y9 I1 o9 x4 B% N/ J  [  @- |. {" T+ n' H- [2 F
    set intersection? false$ l' w1 Q0 L  j# `. u0 r
    set auto? false
/ r0 P4 {0 x2 q+ B7 l) d    set green-light-up? true
2 }/ p- W1 Y9 H7 C5 `" R; ^% W    set my-row -1
- }/ i# M6 ^% e/ F: i: @* G8 w# N0 L    set my-column -1
* X7 e( s9 \) |9 @    set my-phase -1
* g0 j& k7 H$ O; C    set pcolor brown + 3$ T1 x+ m+ p& h) z
  ]' l# }% ^( t) p  K! b
$ {$ z& ]; d$ Q6 _
  ;; initialize the global variables that hold patch agentsets
8 I. \4 Q. f" d6 G! `  set roads patches with
& P/ j( z! b4 O* ~( f- k    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
$ Y2 e# o# k9 I2 |7 \6 o! a7 L    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ i- z4 w6 e1 g5 B: a7 d/ G3 u  set intersections roads with' w- p! z: ?& T
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
% }6 a! m3 M. T: t. e; D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ T: o% o: R+ |$ v  Q1 m" q9 J: h. R9 o# k
  ask roads [ set pcolor white ]+ d. j( p: K1 }* r9 ]# ~  u
    setup-intersections# z9 @. D% I" j$ ?
end
/ j* F& @. e2 }# ?( P8 @8 ?# j9 z. d其中定义道路的句子,如下所示,是什么意思啊?% p: s; S0 `6 ?- ~0 c' X
set roads patches with! B  H" o* s7 l
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 d$ _1 n5 _0 H0 b6 U- [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. c2 A  |/ a: x5 @' S6 x
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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