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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。: S' L6 G, b2 F+ A( h2 [& ?
netlogo自带的social science--traffic grid这一例子当中,0 h; W7 ?) O# u9 W3 }/ u) U" ]* i
globals
3 G* q. K/ ]2 I  I3 ][
0 l3 S& u: f( E% F" f4 u# `  grid-x-inc               ;; the amount of patches in between two roads in the x direction
1 ]. `: y& F1 w  grid-y-inc               ;; the amount of patches in between two roads in the y direction# V3 {( @" i$ [% Z  V
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; b4 u: b" m1 w% I9 p
                           ;; it is to accelerate or decelerate4 p4 j+ }  e# |1 ^7 ]! H8 W
  phase                    ;; keeps track of the phase
; D( H; w- G+ C! F, ?' b0 w# j  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure1 Z3 D4 Q2 o1 |+ P+ W; l
  current-light            ;; the currently selected light
* Y$ ^5 p6 X9 `+ `7 \' z0 F1 Y  t2 c2 P5 }5 A4 g- _4 L
  ;; patch agentsets
1 n$ Q, f1 s. a4 }( T  intersections ;; agentset containing the patches that are intersections& H- Y- a  K9 d8 n
  roads         ;; agentset containing the patches that are roads9 \) L( k  o% A( P: E( G
]6 W( b& ~$ A0 D: Q/ ?; F: f2 B+ e
4 h/ g" ~0 U, j) R) t- }, y
turtles-own( O8 Y& G# J; X/ z/ D
[* h; Y" _+ \; Q
  speed     ;; the speed of the turtle  c" ^. u7 |3 X$ U, [, Z# f
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
3 y' |: j; i! x2 p+ O% m  wait-time ;; the amount of time since the last time a turtle has moved
' v3 r! u, C1 l( k: ^) S. r]2 f8 ?2 t' N1 o1 T: p* p

5 ]* n8 V  D1 S) v- W4 Y- Bpatches-own
& t' {" B+ S$ e" q$ @[
# [3 J2 M% }- R5 D  intersection?   ;; true if the patch is at the intersection of two roads4 ~. L4 x) L( _' J
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 Z2 Z8 B! U1 ]7 e& `6 y
                  ;; false for a non-intersection patches.$ {7 t  ?' q* L; _
  my-row          ;; the row of the intersection counting from the upper left corner of the
. S, y( v* R6 Z' S6 _6 v) s# Q                  ;; world.  -1 for non-intersection patches.
  w" }/ a: x/ D! e, ~! W  my-column       ;; the column of the intersection counting from the upper left corner of the
6 B: l* P+ a" ~! z                  ;; world.  -1 for non-intersection patches.
! r5 Q% j) x  J! S  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ N$ j6 i+ u" H/ @
  auto?           ;; whether or not this intersection will switch automatically.5 k' [, P6 \4 p8 K: l
                  ;; false for non-intersection patches.% I! R" z. `- }! h7 d* S
]" D9 m# d# ?& l- h, l/ W) B
# u& t# t* }  y/ v- `9 W' X

8 ]+ q& P( t  |; y;;;;;;;;;;;;;;;;;;;;;;6 k1 d$ {3 v: b, V
;; Setup Procedures ;;
7 e1 k0 T7 d# \: d0 z6 F& ?8 m;;;;;;;;;;;;;;;;;;;;;;& m9 |/ P# `/ B# P8 l7 R5 V

) M, v% V% I7 Z; _) s3 G;; Initialize the display by giving the global and patch variables initial values.( o, l4 @) ?/ \4 v& G
;; Create num-cars of turtles if there are enough road patches for one turtle to4 L- |2 X" s* O. L
;; be created per road patch. Set up the plots.6 X: k6 M9 |6 ]" |
to setup" F, }# q7 g: @6 y
  ca
9 n5 X/ A+ c+ O  setup-globals$ _$ A( C9 O) k+ C
$ s* X6 W8 Y/ J# X
  ;; First we ask the patches to draw themselves and set up a few variables
; |8 d6 q1 n0 Y$ W$ i7 b8 D3 b- C  setup-patches1 I8 i+ p7 ?; t5 o, N
  make-current one-of intersections7 j8 Q( }* N$ n7 x9 C
  label-current+ e; Q* k, Z3 M; v3 N  S

/ g% T: q) }) y3 e  x  set-default-shape turtles "car"
4 R* j  t! K8 X7 C% U# P/ g. W+ O& h; w4 f) P
  if (num-cars > count roads)
1 n  d3 e- K- i3 `- A0 }; U  [
5 t' E+ e* l+ _) W    user-message (word "There are too many cars for the amount of "
' F7 \0 t0 e# Z/ o2 O; T% Y7 J! G                       "road.  Either increase the amount of roads "8 y6 a" s* C6 Q
                       "by increasing the GRID-SIZE-X or "1 ^4 G' ]* {' l; w
                       "GRID-SIZE-Y sliders, or decrease the "* A7 i# I- j' X0 k
                       "number of cars by lowering the NUMBER slider.\n"" [8 b# V) H" b0 Y0 h% ^( {2 I0 G
                       "The setup has stopped.")
8 i' Z5 N5 @5 H' E4 ~* z9 v    stop. P+ Q& O: k$ `4 x) d: Q
  ]
; t3 [; Z6 Q7 I. K1 m3 B( D8 p) X' y/ C& q) X9 N
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% \& \% y1 w4 I! |# C9 p9 _$ e  crt num-cars
: d" u( t% g  B9 A# Q, ~9 d5 u  [3 s5 H: J+ d7 d7 N+ q
    setup-cars! h8 G  t  I3 R. F0 h
    set-car-color
; U- b2 o, e# ?9 M& N    record-data9 b' a  L5 ]1 H( w4 p# z  K; j/ a
  ]2 }3 @. {6 v+ [' Q6 A6 Y2 b

7 V$ e# k5 @) g' E  ;; give the turtles an initial speed+ {9 H% [3 f# ^: e
  ask turtles [ set-car-speed ]' A* [5 o8 F0 f
( Z0 V" t6 d4 E. _/ L) ~
  reset-ticks
1 c; G( R3 Q) Mend
1 ~7 H1 ?- X- K
) {  Q4 I% `' `* \; l;; Initialize the global variables to appropriate values& n) @% e- y% D7 I
to setup-globals
& X, t7 y4 A& h7 y7 |+ r3 D8 M& ~* l  set current-light nobody ;; just for now, since there are no lights yet. B; N& Y* N' O
  set phase 0
0 F+ i  a9 ?3 n5 @4 o6 p0 k  set num-cars-stopped 0# B6 G# e5 a$ N* F% H8 H0 m
  set grid-x-inc world-width / grid-size-x
/ o- W. J3 M9 r6 G3 M  set grid-y-inc world-height / grid-size-y6 L" l# s! I5 D( r7 z, f

  l, I- A2 p+ ]$ L  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- x/ E4 m' r3 b  set acceleration 0.099
/ w; g' f% O8 mend
  f! @: G% l/ F3 \  N" q, h( w( y5 e# X% K! l9 c
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 O; q6 t$ z* @$ m
;; and initialize the traffic lights to one setting1 [  Y5 d" h: z5 N5 J; v7 V
to setup-patches, h' t. m2 S8 w$ f
  ;; initialize the patch-owned variables and color the patches to a base-color
  ~; [6 E: t) u2 {  ask patches6 u1 X' a4 I4 L# ^) n6 S
  [! E+ C% Y5 [7 y7 n& Y. M
    set intersection? false6 K% ~3 V$ Z) |8 Q9 ~/ z
    set auto? false
$ [' m. f$ t3 T8 I    set green-light-up? true. ^- k. T( R2 D  C
    set my-row -1
6 f) E, ^* J1 U! i. q, P    set my-column -1
3 O, P, H+ x" ~- }3 m    set my-phase -1
! Z/ [( x. W& R; |+ f& V6 @  F    set pcolor brown + 3
/ X+ p. L: D7 F0 h% ~8 E1 I+ e  ]6 W! ]3 H4 d# U: ?/ j) N3 B7 U& I

" N1 D3 E1 v9 a7 ?3 ^  ;; initialize the global variables that hold patch agentsets
/ N. d& k2 P, z9 Z. c  set roads patches with
/ l7 Z! D, \! K+ X3 T3 m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 G5 D# }+ ?) r2 M: D    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 `' y" n+ r6 q
  set intersections roads with
9 b' `/ N# I# {    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and+ {3 q& T% n$ }/ H" t
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ B, ]: g- X% _5 Y$ y- Z# }1 S
4 W9 a$ U' W% c" Q" U  ask roads [ set pcolor white ]
# X! I, M* x5 p* x8 v2 e# @5 c    setup-intersections
& G: l) [! n! t: mend
" T$ x$ ~; o9 B: x+ R. P! G0 e& |: Q其中定义道路的句子,如下所示,是什么意思啊?
2 R$ J3 N5 _; O set roads patches with
) Z  P2 }5 `0 I) o4 c4 Z$ @; \: y1 K( f    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ `6 j. W) `' s3 N6 m1 k
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; M" E, n( [* A
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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