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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  I6 j4 t6 \$ q  Y  p. z7 a9 @netlogo自带的social science--traffic grid这一例子当中,
3 J) D  h  q& y* i- Oglobals
3 n( Y# L3 u5 m/ S' r, [9 [[
  o  @3 w. i: ]( ~  grid-x-inc               ;; the amount of patches in between two roads in the x direction
# x+ {0 K  q" Z- r* s  grid-y-inc               ;; the amount of patches in between two roads in the y direction
1 @) }+ C2 A' g4 [( g5 A  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 R+ V, k% R' j, ?% n) r0 }                           ;; it is to accelerate or decelerate
2 B) o6 r' C+ M$ Y  phase                    ;; keeps track of the phase
6 j; M4 E" W! ^  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
" x# B3 |( y) ^: J, v1 x8 A  current-light            ;; the currently selected light
  ]7 l0 n) }" a. K
" M( l! O' \+ c9 A# A; f  ;; patch agentsets( R* b) v  z0 v1 h9 _
  intersections ;; agentset containing the patches that are intersections
9 y, t9 e* p' P" S& O  roads         ;; agentset containing the patches that are roads
) l; B/ r/ m! \! H]+ U0 h( T1 b8 {0 q4 |
3 `, r- U% T- D! ^; j9 e2 X5 ^* Q( Z# M
turtles-own
" G4 D. b) D8 |[; N. `8 e9 k5 z2 Q# g: D
  speed     ;; the speed of the turtle( l! Y, s; ~( [9 \7 g) s6 B: t
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
' P. q4 G- t: c, M3 u1 h  wait-time ;; the amount of time since the last time a turtle has moved) X* k& V5 k0 e! a, B
]( u$ X) T' e& ~; H
. e# _! r1 D- l& O. ^, U
patches-own" S* E- M: F, _! H
[
% d+ |. m/ C+ k$ d! O+ {& V1 D  intersection?   ;; true if the patch is at the intersection of two roads# T1 c7 o$ L+ q1 `+ v
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.! c& p' |0 P0 K3 |! F9 E
                  ;; false for a non-intersection patches.
& U" b+ D+ C7 g$ X  my-row          ;; the row of the intersection counting from the upper left corner of the
. s. j. }: i# C3 c" y) }! ]" U                  ;; world.  -1 for non-intersection patches.) ?; A" u% b3 P) i2 Y, }4 ^
  my-column       ;; the column of the intersection counting from the upper left corner of the1 r* l8 d2 k$ l" i9 s' D2 T
                  ;; world.  -1 for non-intersection patches.- z$ J" @( E9 w! ?! o
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) g8 o1 D( Y) W0 D1 R3 r  auto?           ;; whether or not this intersection will switch automatically.
4 p  y/ D/ s0 f( m* f                  ;; false for non-intersection patches.
0 \! d+ j! I" F' D]
, d8 Y- H9 l$ Y: t+ X6 `$ b* D) l/ E0 N" w; X1 A7 n" k* q# j
% \6 u6 E+ I- r5 ^0 q! K- B8 e
;;;;;;;;;;;;;;;;;;;;;;5 t+ ^' J5 ^; b4 o. S
;; Setup Procedures ;;
6 K3 ^6 J7 W4 G0 R% q  @( T/ P;;;;;;;;;;;;;;;;;;;;;;0 D7 M/ a/ M9 s8 j( B, U( j( y4 B

' j" E5 L" T. @& W( ~;; Initialize the display by giving the global and patch variables initial values.
% o9 u- H* f" d5 X+ J;; Create num-cars of turtles if there are enough road patches for one turtle to
- L3 @8 k/ N: f;; be created per road patch. Set up the plots.7 D6 b: K6 V/ _& R% Z9 O
to setup9 ?) r% i) e, R/ Q, G$ f
  ca
( l3 q# O  E* ]) e* l  setup-globals
8 a6 [6 ]( G; L9 R, A$ k7 j2 i
- U/ I, H' \) G3 \* t  ;; First we ask the patches to draw themselves and set up a few variables1 l5 L# f, D2 X" R
  setup-patches
( ^1 I  m; q& J; j" W, ?  make-current one-of intersections
$ b/ }8 h* F6 I  h- j  label-current6 i# Q0 r  R6 d2 J/ g5 w1 ~. D1 Q! x
- k9 `" J5 V4 e# x
  set-default-shape turtles "car"8 S( [' o; I# I. Z7 p5 R
5 l. }3 B3 E4 D" h
  if (num-cars > count roads)
  w8 c/ X7 C& g  [8 w1 {4 G$ y9 ^0 b9 D
    user-message (word "There are too many cars for the amount of "6 e! c7 |- i- h9 l; q
                       "road.  Either increase the amount of roads "0 F$ F5 g1 p5 g' O8 h* y
                       "by increasing the GRID-SIZE-X or "- R, q1 r- I& w+ [9 K' O, X
                       "GRID-SIZE-Y sliders, or decrease the ": Z% g4 M& E2 ?4 m
                       "number of cars by lowering the NUMBER slider.\n"+ _2 i( o# K* c& _; r
                       "The setup has stopped.")' l$ w3 y3 d, f
    stop
. M: @9 V! G8 D* N2 {  ]  M! D/ f* e0 |8 ~9 e( }

3 t! G+ {) ], p. _4 K( G& S- y  y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color+ v  z/ f1 H- l% E1 ^+ c6 E
  crt num-cars) h# {4 E: y" O0 C5 E
  [3 {3 w' ^' N# Y7 {& W
    setup-cars
$ ?2 n/ A' B  I1 W" B7 W/ Q! [    set-car-color( E* X! w- j8 T; j" v; m, X2 Q
    record-data
  b4 o/ k* [* ]+ D  ]' h% p" B+ }5 b! v4 H6 F: H" j9 b
" Q1 x, j# G5 v3 d% a8 ]1 J& o
  ;; give the turtles an initial speed
5 _9 s; x3 _- j1 S0 g& m: ~3 M  ask turtles [ set-car-speed ]
2 X7 s5 t. ~- E9 b: ?; k, k( F3 ^! x" |  K1 |% v
  reset-ticks
. a5 P2 Q. H3 p( b' O" W( |end
. m! r! p, w! ^3 i2 `/ g1 p! ~: {- n5 _4 A6 q
;; Initialize the global variables to appropriate values
) q/ G( c- e3 Dto setup-globals# E1 v# U( d2 G, U8 A
  set current-light nobody ;; just for now, since there are no lights yet
& G$ z  g3 g4 L* F/ v1 J  set phase 02 `# W, y! y1 c+ A# t- c
  set num-cars-stopped 0; w: J0 E! }4 f8 R. p9 d$ c
  set grid-x-inc world-width / grid-size-x) y7 s' Q$ `& Y1 c
  set grid-y-inc world-height / grid-size-y
: i% K1 L% p8 @7 o( k
+ |) Z" u6 H3 \7 _" A  ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
- p* t; W/ ^$ R( S" ]  set acceleration 0.099
$ U& ], O* R( `; a: s+ Cend1 `  }/ W4 X4 O6 @, m8 G

- O; k: Y# f# Q( u' }/ D: r;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
1 j' h# v* r+ s/ j. P* W! t;; and initialize the traffic lights to one setting# w" |" u% u" m+ Y. v& r+ E( o
to setup-patches
6 D5 _: C9 t- b% J, c: l1 t  ;; initialize the patch-owned variables and color the patches to a base-color/ h: G0 `/ [5 h2 q) h" ]0 u
  ask patches6 _1 K- N) U2 v
  [
$ i  v, {1 {7 P5 r3 }5 S+ d    set intersection? false
4 z# |/ i: W- J/ y# z0 X3 k" w    set auto? false! v. X$ I1 E) @) ?. d; q5 F0 D2 R
    set green-light-up? true
) u" a; L& D$ d! b    set my-row -1
# }4 `8 l6 s) |" _4 F- h* }    set my-column -1
" r: s) b$ V: b' \- X" N# T9 t& J    set my-phase -1
# k6 |- s" i: V$ @% m3 D    set pcolor brown + 3
6 ^, D/ f$ V" M, ]  K  ]& `! \8 j5 b2 x
9 j) [; F# c! W6 c8 v! g
  ;; initialize the global variables that hold patch agentsets5 f; y, F  J' @+ Y! V' k
  set roads patches with. l5 \; ^- E( U, R) w
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 s- D, Q: S6 {9 j) ]5 ]! }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 Z, \8 k  E( U" ?' r; S, H. E3 p  set intersections roads with
! M9 e% I) ^, H* E; A2 q, D% a& \    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
  H) }4 @& ~( l9 `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  e8 W' K2 Z! ~2 m) T6 Q2 F+ E( T5 y0 P8 W( z- m5 ?, r
  ask roads [ set pcolor white ]1 @7 ^( n0 V2 d9 N. {. L
    setup-intersections
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其中定义道路的句子,如下所示,是什么意思啊?. |. I& P; s7 j& \4 K  [
set roads patches with
6 _4 {  G0 _* A+ @    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
. d0 E  A+ y0 ?' y# S    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
3 h6 Z2 b1 o$ j( {( 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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