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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。
( }6 Q2 q* U6 f6 _/ enetlogo自带的social science--traffic grid这一例子当中,
1 i& Q: a" u( D% D7 X1 oglobals
% b% A' n  w6 D/ j, D) X1 U: \0 L[+ f/ }6 z8 G2 f6 C$ S' |8 @* |  z
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
+ j% _( j1 b0 @+ o' B' o! P9 Y7 X0 g7 [  grid-y-inc               ;; the amount of patches in between two roads in the y direction
# ?- V2 j; N5 N( ]7 Z, R  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
6 C* F- q( K: H* [                           ;; it is to accelerate or decelerate
- t# c' S/ u: x, u* V+ U8 L3 u# d" e  phase                    ;; keeps track of the phase/ w! Y* h' `7 }* a
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
6 `& J( T( Y& W$ e  current-light            ;; the currently selected light. j# G7 e# L8 |7 P( M# F: g
, {/ \7 [* r9 D3 r0 s4 `" k( G
  ;; patch agentsets" E( \# r. e  z' P5 }
  intersections ;; agentset containing the patches that are intersections7 l2 l3 a1 \8 Y/ _) |2 P) e+ r
  roads         ;; agentset containing the patches that are roads
) ^7 U! l2 {# u. H2 C" w# N- Q]
; d" _( |3 h3 \( g  H; @" j, o7 ?4 J4 q
turtles-own
, H! X9 b- ]( b0 Y2 E[
2 W1 k5 C. R& l  `, ], q0 |9 p  speed     ;; the speed of the turtle
1 f4 n7 O% k; a2 H7 C7 d/ R- t  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
9 p0 D( c. I& t# P' p) F& J9 Y  wait-time ;; the amount of time since the last time a turtle has moved
2 }5 E1 ^3 Q7 H( D0 S' g]8 b- l5 T5 Z! X4 V9 Q- J
: W: I) Q4 M, i/ S- c+ r
patches-own
- Q! y6 v$ N+ j[" i: @, _+ M' e: y
  intersection?   ;; true if the patch is at the intersection of two roads7 S- d" ^1 A/ c! V, `
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.# @) \- N5 Q9 g
                  ;; false for a non-intersection patches.
$ H- [- w; M# |1 R( R' @  |4 e  T+ X  my-row          ;; the row of the intersection counting from the upper left corner of the
6 w8 m2 G/ L) ]# x. R* J, |4 D                  ;; world.  -1 for non-intersection patches.. r7 c* m' Z0 h: P
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 _  B) w; ^, h; Y                  ;; world.  -1 for non-intersection patches., n2 R9 l- d: C# g3 I8 F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
) U, A7 s9 q% ~/ [+ F  auto?           ;; whether or not this intersection will switch automatically.
, t* @. U: g$ I0 ~! `                  ;; false for non-intersection patches.) Q9 L/ c) X. H5 l
]
" J2 @% E  Z  E/ t! y
; [3 b. a1 }( z3 A8 Z' {7 B3 t1 @( S9 N* D; u* B3 G7 z
;;;;;;;;;;;;;;;;;;;;;;
; ]0 A- |4 C9 q3 w( m/ e- c;; Setup Procedures ;;
1 C& Y# q+ B, D: S1 b) V" ~;;;;;;;;;;;;;;;;;;;;;;) ?. @# v! D7 U$ K

. G! I4 ?9 p7 E+ M;; Initialize the display by giving the global and patch variables initial values.1 m- @3 `* \% O2 D8 @& |; X
;; Create num-cars of turtles if there are enough road patches for one turtle to4 \0 z. y3 i( o+ W- M
;; be created per road patch. Set up the plots.
& g% I9 ?: t+ G3 E2 Lto setup5 \, n# R; l# Z! w
  ca4 G* }2 p) K, [
  setup-globals
5 h* }; P- F* {; F" k2 H
) ?% R6 e- F6 o6 M! ]7 J  ;; First we ask the patches to draw themselves and set up a few variables% W* f0 y3 G' n
  setup-patches
( }8 N' R' e# b% |- K  make-current one-of intersections
7 {4 W5 U1 R, [" z$ y  label-current+ x$ ?* e3 p6 l& c% }

6 H/ ~9 z. a4 Y1 ~% ?/ Z  set-default-shape turtles "car"
* N+ g/ h" }6 i, x- N
& L2 }( q- m( Y0 d5 ~  if (num-cars > count roads)
  ^; Y$ Y& z6 U  a& q, y: R8 n  [
$ \2 u, e7 r2 B8 |6 T    user-message (word "There are too many cars for the amount of "
" J! j' R# H: S+ ?, k) w  [                       "road.  Either increase the amount of roads "! d; G' F6 `( t( k- C
                       "by increasing the GRID-SIZE-X or "3 M6 @/ Y( w. W) I# R
                       "GRID-SIZE-Y sliders, or decrease the ": M0 `0 X9 y( ?
                       "number of cars by lowering the NUMBER slider.\n"
' ?. n% a% |9 T6 ?) R$ B                       "The setup has stopped.")6 l. J: }- o; h* V+ j# G9 o
    stop+ G4 Z- |% Z2 Y0 e) h3 l. D
  ]9 }" n7 k9 z" g& i7 P& e
$ W* S, d" P, Q/ U  q& v8 i* N
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
) L2 v) C$ C0 k# b+ d  crt num-cars' F9 o  v5 A4 y; ~; v0 f3 D% y
  [
  ]) V! E, n) B. D    setup-cars
, V( m- n6 l& }+ Q8 b+ `  o. S2 J. r    set-car-color
. F) n, d+ i3 ]3 w& X    record-data
2 Q) b4 m/ \% j3 c' O/ ^  ]
, c: l; V$ F1 R- u( g6 H  c
2 I8 a. y2 d9 Y6 \2 [! R7 s3 w# X  ;; give the turtles an initial speed
# d& l8 e: ]1 N4 n  ask turtles [ set-car-speed ]0 \) x3 a) k5 \
8 f* N, ?& k  |6 I( B1 R1 q7 u
  reset-ticks% v0 q) a  m  ]6 A
end
3 n, X* N+ C6 K: M& J
( B) l" A' P1 u;; Initialize the global variables to appropriate values
" P. O+ q: I5 x9 \  sto setup-globals
4 X: a! B7 Q& T& |& ^$ o3 ~2 ^  set current-light nobody ;; just for now, since there are no lights yet
$ m4 }; x6 C" u  S) p4 t* A  set phase 0& {2 E' U' T& L: t$ o% a
  set num-cars-stopped 0
9 \$ i( j8 [) @. s6 |  set grid-x-inc world-width / grid-size-x! }% N* w9 A; Q) Y7 @2 ~" ~
  set grid-y-inc world-height / grid-size-y
4 `8 ]7 j8 g. z& ^8 a1 C- P0 K% d. P6 s0 z) T
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
+ \7 \$ F+ x: [  set acceleration 0.099" ?6 _4 K1 P8 ~0 X( [) I$ Q2 v$ e
end5 t2 a; {* g( h6 \; Y
# ^9 E( V- K7 F0 h: T
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,5 d2 T  F; A+ }7 z, B8 Q4 L
;; and initialize the traffic lights to one setting, P" B* i$ S( M0 k3 t/ {
to setup-patches
- P0 Q1 ?; R# ?& B  ;; initialize the patch-owned variables and color the patches to a base-color
8 r1 i/ v& b1 L; L# ^/ I; v  ask patches. }5 K: `% d  s% f& q# E
  [
" k4 @; G* ^- }& I! ?2 A    set intersection? false! U- x8 z" W4 I/ R. B& L  ]. C
    set auto? false
3 Q7 D3 n/ u) W. N, \5 M; z- }    set green-light-up? true: h/ H% K% R2 I
    set my-row -1
  v; G4 l( m  r6 i& {' `; ?/ b# u    set my-column -1
: n0 p( D8 D& `    set my-phase -1
1 e. z: ]8 {; H8 c5 r: K$ ~    set pcolor brown + 36 {; ?# Z( r) n3 ]# S
  ]
5 b* T1 S& T" p' \/ x& C, ?  n9 O+ R! m
  ;; initialize the global variables that hold patch agentsets
' F& c' X& E9 m  set roads patches with! c+ s: c. {$ L
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; d/ s0 _  r2 V1 Z
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; s6 q& g- R; P; Y  set intersections roads with/ Y6 Y2 J# }% B/ U' U9 L) u
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and  H( ^. Q0 l( @: _* w& t5 v, `
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
+ h& S# s: V  L
5 u8 }" ]7 p9 u( l8 y* O5 l  ask roads [ set pcolor white ]4 R$ h3 O  V" y* x
    setup-intersections
& |- W$ P0 j1 Wend
& r3 \7 Z5 m1 \2 E其中定义道路的句子,如下所示,是什么意思啊?
5 }2 P' F+ d, y0 C5 ~+ K set roads patches with+ ?" `/ _. d# J/ E$ S) B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 U; E8 z/ H' }2 A8 N. r$ T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]4 N% ^# F4 O$ @
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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