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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。7 |! a& H  d3 N! _
netlogo自带的social science--traffic grid这一例子当中,
1 B9 H. ^) f7 _8 T  Eglobals
) N4 b9 d9 O* Z6 x2 `: L: @[! |: E6 z4 o  n* T9 J7 `$ e% }
  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 s; r: o) B6 I, ?
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
+ C1 `5 O3 z  Z* R  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
+ q1 A' c, Z3 t: G+ i! c                           ;; it is to accelerate or decelerate
) b" G! g$ B/ T/ g6 f  d; h  phase                    ;; keeps track of the phase
5 c' @# {! [* p8 R6 D+ X1 h# V  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
( U  _  ^/ u" c  current-light            ;; the currently selected light
/ x8 q8 N6 v) s# ^9 J. x. Z
1 Z& d; M3 W5 d9 D* i/ ?5 }  ;; patch agentsets
; [+ h, J1 t9 y) d) ]  intersections ;; agentset containing the patches that are intersections
$ b' s9 [7 u6 L+ }3 q$ D  roads         ;; agentset containing the patches that are roads: w( ^* l' h  F7 D% n  Y/ \( D
]. u' t9 B5 K! a* B: c# k
. ~* \! g% {9 v4 n5 w, f. n
turtles-own
8 ~3 m# w' D+ I[
5 y9 l( Y' f, d) G  speed     ;; the speed of the turtle
$ P3 v2 [2 e+ w+ ^. u  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& [. R* b" i( N. c% ]! I  wait-time ;; the amount of time since the last time a turtle has moved2 x7 J9 A) P  `) p$ T+ E% K
]' T6 A7 {. W( W5 I) P
" W( z' q$ A+ ?! U" w
patches-own
6 [# |/ p$ U2 y+ ~[2 t" E- L1 B" ~" k
  intersection?   ;; true if the patch is at the intersection of two roads: }5 ?/ ~4 W2 b$ a
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.4 e- N, k5 _  Y' D% @5 ~) Z
                  ;; false for a non-intersection patches.
6 g( x" N% A  D; f  my-row          ;; the row of the intersection counting from the upper left corner of the0 ~7 z7 R- N) I7 l' @  V8 o% Z
                  ;; world.  -1 for non-intersection patches.
3 N/ l7 ?& w# `, B1 c  my-column       ;; the column of the intersection counting from the upper left corner of the- `" Q! z+ [  X6 `* J
                  ;; world.  -1 for non-intersection patches.
- d- @: y/ a/ [+ r  h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
/ r& O) F- E% W1 E6 H  auto?           ;; whether or not this intersection will switch automatically.2 v1 i5 {' n( `
                  ;; false for non-intersection patches.
2 G6 I2 l4 h1 x- L]0 n! L2 |' m% V; k$ m
' `4 I1 X* ]9 ?; F
& o1 Z3 S+ n8 @
;;;;;;;;;;;;;;;;;;;;;;& r2 m8 S% J0 O& J" h" d9 K1 S
;; Setup Procedures ;;+ u# k, z+ L9 Q! ]/ B
;;;;;;;;;;;;;;;;;;;;;;
. g6 U: D. g5 _  ^$ I, ]- y( T! R( G
;; Initialize the display by giving the global and patch variables initial values.
2 E, ^# Z4 m9 J;; Create num-cars of turtles if there are enough road patches for one turtle to- P' V* X: B2 X
;; be created per road patch. Set up the plots.. ?  B# ?. @7 u
to setup2 T+ {3 I. G: q# J- @, q& t7 a
  ca, D7 r0 @& C+ W0 r
  setup-globals
5 r: s! z8 R& [& p" m2 C
% ?- K, v; R1 J  ;; First we ask the patches to draw themselves and set up a few variables
: a/ Z5 n6 W' n  setup-patches
# O$ k4 a$ U) @  u0 S  make-current one-of intersections5 G9 D7 h8 n* z6 l5 o
  label-current
9 ]( P: Z6 I' d8 u
0 I0 K, I) l8 l3 V% ]  set-default-shape turtles "car"
1 u: @% J* x# p4 k. m
6 j( s$ k" W4 U' ~, A4 o$ S. r  if (num-cars > count roads)/ K1 |; Z. T5 f: l1 F  [, Z
  [4 [) }: `6 u0 |$ E( T3 U
    user-message (word "There are too many cars for the amount of "7 `* A4 F6 m/ f0 k) U) W' _
                       "road.  Either increase the amount of roads "/ p8 H2 b+ C4 G! M% j
                       "by increasing the GRID-SIZE-X or ", q8 \, [& L% ]. _7 h7 D( f/ k, X( u! {
                       "GRID-SIZE-Y sliders, or decrease the "
: |( W) J7 B; M" }                       "number of cars by lowering the NUMBER slider.\n"5 r" F1 m+ e4 h- @
                       "The setup has stopped.")
% ~( G0 U3 s) f- z    stop
; i- e! F2 p! B! [! C. t' ?4 C  ]
' K$ G& {, C/ e
' g) y/ @, t4 c3 {# S) ^# e5 F5 B  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; k4 L$ I" F3 H6 f7 Q  crt num-cars* v4 c$ Y4 F* i1 H2 ]0 |5 [0 j
  [
1 h* R* }, ?( K    setup-cars& B2 o( x3 \; ^" y! [" j
    set-car-color
! ?1 A: h2 [9 B: t0 V: Y    record-data) k) b- B$ d) w9 W: B) E# W. n# T
  ]
# E7 R% \$ ^2 Y6 c1 q: W1 m  e  P3 ~( S
  ;; give the turtles an initial speed9 ]1 P: O4 R- d$ F: ]- b  ~+ _8 U
  ask turtles [ set-car-speed ]
& q2 }" R8 S. z
( I& W9 Z* q+ `9 `  reset-ticks
# N  L; b; m1 ?end, K: N: _% k. u# v# e2 B
! e! U: l/ |. T& C
;; Initialize the global variables to appropriate values, H) l  e7 N6 w8 E( ~2 G8 l
to setup-globals+ x$ p/ \5 ^3 F. S9 @% }- k
  set current-light nobody ;; just for now, since there are no lights yet
: s) P2 G$ @! P8 h: P0 i! \  set phase 0" s; N4 D. v' ]/ U! y* i8 p
  set num-cars-stopped 0- q. z: r" Q& `
  set grid-x-inc world-width / grid-size-x# p1 O8 L9 V" U6 |( t
  set grid-y-inc world-height / grid-size-y
) k2 p' l0 R0 L6 n2 C2 z
8 v- C; o' ]) {3 ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ Z4 k0 w* W+ H# Y  set acceleration 0.099
4 M' V5 a3 t8 Zend) q7 B, z* I/ V) o

( ~, G5 A: g+ n0 W; ^9 Q;; Make the patches have appropriate colors, set up the roads and intersections agentsets,' {5 o* {) \. d( k6 x. u
;; and initialize the traffic lights to one setting& H8 x* w2 |8 T
to setup-patches2 `. J& i+ o& M' w3 `( _
  ;; initialize the patch-owned variables and color the patches to a base-color5 |$ s1 A& \1 M6 b5 K
  ask patches
6 k- p9 S# \# t0 T+ d5 `. q  [2 O, I# y* s. f6 ?) Z6 |
    set intersection? false
8 i' ]3 ]$ J' U/ A$ ?% ^    set auto? false5 p7 G" p- R) |0 B( S) I( n
    set green-light-up? true
/ v0 Y  y& e! u    set my-row -1
9 P7 D6 E. R5 u( \    set my-column -1# n; l8 I* Z! y7 V3 @5 a
    set my-phase -1
2 i  F  z, \# l) [    set pcolor brown + 32 i: X1 X% R1 o: r
  ]8 p0 S. `& k" I9 R! s

# y% R; h6 I+ v4 A. m' ?3 r) C  ;; initialize the global variables that hold patch agentsets$ ?0 X  G. C9 t
  set roads patches with9 u: i1 @7 {$ ]; C; U  V( K
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or' G3 ], Y/ P* Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]6 G  V$ P3 E7 [& N5 g; H: A
  set intersections roads with( H( }- |% Z. Y+ U0 l, }( T  S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and& |% N6 }( o7 T. e, R5 W" ~; A
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) Q4 X( L  _2 n7 Z* z: ^* {& C2 a
/ F& I3 H2 J: v$ M$ z$ f9 G  ask roads [ set pcolor white ]: E% k" Z" h' x
    setup-intersections
, Q  z8 M6 g; `9 D% J) t6 z: hend( G- a) S# s# N1 R% s/ E. z& ~! `
其中定义道路的句子,如下所示,是什么意思啊?- x8 }' ~* N4 L: A- G- T& X9 \" [# U
set roads patches with
# o. Q/ ^9 z8 p3 e/ C+ ]. l    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or5 \, e+ B! P, O8 L. w3 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]/ N# u* K/ u  B' N
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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