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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。
. L  k/ F& l2 L, dnetlogo自带的social science--traffic grid这一例子当中,9 k7 J# T) j; ]5 ]
globals
# Y: k7 M4 T& b9 o$ O[7 v" D" @+ D7 i& R' S% H
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
- ]2 H. B- f7 [  c/ X  grid-y-inc               ;; the amount of patches in between two roads in the y direction
/ D1 N) x! H$ n  acceleration             ;; the constant that controls how much a car speeds up or slows down by if3 E! c: t8 @' c. Y  j! w
                           ;; it is to accelerate or decelerate. Y" x1 d) L, N/ ]3 q
  phase                    ;; keeps track of the phase: u. ?# ~( ^2 o/ Z& ]
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% M4 o- S' [6 d4 P- e* b. \
  current-light            ;; the currently selected light
  u9 |) }/ U2 k
+ W+ ?& s! E$ j- P$ z  ;; patch agentsets2 s& Q# P+ I$ t3 V$ w" H
  intersections ;; agentset containing the patches that are intersections+ |) {( z/ L+ t, {1 D+ A
  roads         ;; agentset containing the patches that are roads
" |2 U; }5 N  w, @* B$ i* \]$ s  C& m! M+ m1 L
- B, F. `. o6 r& J0 ]0 U
turtles-own. ?! h7 s$ a; B# i2 O4 K6 s, @
[
1 J" u8 S6 l/ T4 k1 \; E) @7 x1 O  speed     ;; the speed of the turtle
9 t( R9 m$ b! q* r  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
( l# |5 }- X/ E6 t5 n  wait-time ;; the amount of time since the last time a turtle has moved
: O( M; Z9 i6 V]1 c' }" y. a2 q# v! _

/ U8 C  G% t" J  d9 K  w( a' ^patches-own
9 z" H& N7 o7 I" w, A% a[; w- A; Y' e% r/ s4 _9 d7 `
  intersection?   ;; true if the patch is at the intersection of two roads; x7 W6 D: Y' w9 h" p( z
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* i- w6 u7 `0 @* H( t                  ;; false for a non-intersection patches.# T/ N5 O1 m- T  c; j
  my-row          ;; the row of the intersection counting from the upper left corner of the3 I8 H5 O2 J; J, p' ~; z
                  ;; world.  -1 for non-intersection patches.5 {" l$ A" }7 J4 R9 t
  my-column       ;; the column of the intersection counting from the upper left corner of the  O; f4 R6 h% n8 T4 [
                  ;; world.  -1 for non-intersection patches.) x8 o1 K/ `5 m" t/ ^
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.& Z; o. A) s# W( I4 A
  auto?           ;; whether or not this intersection will switch automatically.. p' X1 d9 g( {  V
                  ;; false for non-intersection patches.+ C" w  l/ a: ?: G4 ?% ~
]; U0 R2 w) t9 x9 W! B; Y

% A4 o6 \, ]' s
5 g7 Q2 d7 m/ \2 _;;;;;;;;;;;;;;;;;;;;;;2 Y. o+ O8 \1 i$ }8 X$ Z! O
;; Setup Procedures ;;
1 X0 X- d2 {/ ^9 \' W+ g;;;;;;;;;;;;;;;;;;;;;;
& b+ ~% w1 C5 d9 i) U
" P% h1 L8 A9 U0 T2 S;; Initialize the display by giving the global and patch variables initial values.
; C* |* Y) v7 A' g  X2 `- W;; Create num-cars of turtles if there are enough road patches for one turtle to
' R  n8 O+ H2 _& B/ K;; be created per road patch. Set up the plots./ K! p8 ~7 @* p# K3 t; b' V1 [
to setup
7 F: J" E, ^  b  |% \/ w  ca
- M" I  f+ A4 [0 h1 L  setup-globals% s( ]2 c5 H4 i6 i5 @! {  o

- L- t  f) F9 h) k  ;; First we ask the patches to draw themselves and set up a few variables
/ W2 ]7 x" s1 T& n9 ~8 n; R# P2 y  setup-patches
/ X6 i1 x3 Y: I# v  make-current one-of intersections. Q9 ]7 ^6 X( s* R
  label-current
0 ?9 j$ e* X$ |, \1 a8 {+ M% L8 _  ?4 F8 T5 }) U0 ~& M3 ^% f0 t' T
  set-default-shape turtles "car"9 s) ~* a" R8 M7 B' m: S4 w
0 _# j: d* M* j6 b; C
  if (num-cars > count roads)1 m" O, P6 |- E, b5 m
  [+ R5 }0 T& p: K8 Q9 s! J7 r# F
    user-message (word "There are too many cars for the amount of "
- x4 b. F2 T& o6 c/ k' t5 W                       "road.  Either increase the amount of roads "
5 M% L1 M9 N7 T7 b" b                       "by increasing the GRID-SIZE-X or "* a$ `' x, m$ O7 J, [' c
                       "GRID-SIZE-Y sliders, or decrease the "  W3 _& I: s# E2 O
                       "number of cars by lowering the NUMBER slider.\n"
  ?  |( s! e! W( C1 @' i2 j9 v                       "The setup has stopped."); n3 u3 [" A9 H9 D! Y
    stop
/ _8 g6 `/ b4 |% L  ]) o/ T/ C; R. W# X3 X
6 V2 V! b" P: q1 \4 P8 D
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color( Z4 x- `( Z, X7 g* z3 U' w2 W
  crt num-cars
" l+ F; }9 |( Y. F8 \/ e! Y  [
5 e! F4 U" H' j. t7 J    setup-cars
0 k: e0 V/ g, @5 f$ e# ^8 ]" P1 C9 x    set-car-color9 {- X" }# |5 z4 c; j
    record-data3 q5 ~1 v9 g0 q
  ]" x9 |( r+ Y$ V; n
0 |" S  ]% B% s* O
  ;; give the turtles an initial speed
& N% W. {6 ?+ K6 @  ask turtles [ set-car-speed ]
* K' I( o7 r' d& C, ^% h4 ~! N: U
/ ]5 y3 L3 X* x8 @9 J9 Y: E! X  reset-ticks
& ?) m  A3 l. G8 ?3 n% [end
& ]  k& a/ k7 j1 k- Y, Z5 B. H+ `$ C* f. g1 ]4 k5 Q
;; Initialize the global variables to appropriate values) }( V# t2 l0 \* Z
to setup-globals
  K! W, F1 O% r$ Y4 K* p' J2 s  set current-light nobody ;; just for now, since there are no lights yet
3 L$ @# j8 E/ o( z( `2 b9 E. f2 C  set phase 0! w" a* F" b4 V9 s6 S4 r
  set num-cars-stopped 0! w2 }9 T" ?2 i( V' c
  set grid-x-inc world-width / grid-size-x9 `9 d" e# s/ l& j+ X
  set grid-y-inc world-height / grid-size-y0 D$ ~9 n7 p, I

- X& y( L$ i$ m. I4 e' v( g3 M  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
# R3 F4 Y2 b+ x1 y- W. p1 K  set acceleration 0.099- B! E9 l) l9 j% b8 W
end
: J4 i7 m  S9 {' a5 f- |6 P# }4 W' f9 R, L+ M( H
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 y+ B! h  O- [+ j& i;; and initialize the traffic lights to one setting5 W0 F9 e1 m4 C
to setup-patches; l* B" |; k' ]" m7 ^0 {' L/ G  h
  ;; initialize the patch-owned variables and color the patches to a base-color
/ ?% T" ]7 l; ?: t' _* I  ask patches/ ~+ ~& J/ V9 {8 `1 C: J: u
  [; C) @' d1 p! M& W+ l% p
    set intersection? false: p6 ~, j  R+ {( C
    set auto? false
( i) N! t  q2 x0 ]2 I6 f% |    set green-light-up? true
$ E, g. _6 I) M' a3 }    set my-row -15 _5 a1 z9 h2 A) q6 c! K
    set my-column -1
1 T: g8 S2 s$ G" F: ~5 l    set my-phase -1# [( S; O8 h( \+ C
    set pcolor brown + 37 |1 V; n1 U, F- S* ^# x
  ]- e, c9 v" s! b7 |: X, `/ f% ?) k
5 F8 O- w7 t. A- L! L
  ;; initialize the global variables that hold patch agentsets
* {, s3 L% j2 d; U7 x  set roads patches with
1 I* E2 T6 q/ l4 [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
  y& d( J0 ^& k  t! S7 z8 L6 o; I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 y5 i4 s' }4 B# p  set intersections roads with- x0 U/ y. F1 X
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 n  ]( q% g; }% @! D
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
! M6 V, `0 z% k) G  A
! U/ p8 G. c# G5 q) `$ h) K  ask roads [ set pcolor white ]* U1 @6 P8 Y: s; C# c
    setup-intersections# \1 H: |% Z4 A% i
end
  j2 v/ F5 i& F+ r其中定义道路的句子,如下所示,是什么意思啊?4 D' ?2 L& R) ?
set roads patches with1 A) F- {, U' z& z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* \% w0 x5 d$ C6 g$ s  m- H
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  J% ^. c; u6 L( j$ c" Z6 {( _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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