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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。0 k7 j8 F0 m' m2 `
netlogo自带的social science--traffic grid这一例子当中,7 F$ H( a* K! X
globals/ ]6 @) h4 J9 ]0 E. q1 X
[( R/ A0 L6 X0 n# x
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
& \" x  f6 F9 {9 i+ I  grid-y-inc               ;; the amount of patches in between two roads in the y direction
6 r6 I3 C( g7 l. o5 _; x: {  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
8 {9 m/ g0 I- S" }+ Z                           ;; it is to accelerate or decelerate
/ _1 R1 j# K* T8 ?5 d  phase                    ;; keeps track of the phase
4 d" f* K/ Y: a5 c# W7 k  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
+ N& ?# M5 W& h& z  i  current-light            ;; the currently selected light/ S, c9 c: ^* \

; W" S9 o7 R& w  ;; patch agentsets. ?! W! e, f; z' k4 U7 G
  intersections ;; agentset containing the patches that are intersections, v/ a( E; n" k
  roads         ;; agentset containing the patches that are roads& T8 @% L0 ~/ j+ N- ?
]5 O$ `0 N- \9 p# g: c

8 ~) ^5 S% R/ Lturtles-own
% j0 {7 i2 p! J$ k* [" [0 A8 ?[
" u4 K- i& ^4 f& b) i& x  speed     ;; the speed of the turtle
9 P, L! `( w% P& W6 _% ~  up-car?   ;; true if the turtle moves downwards and false if it moves to the right, L5 W. j; U/ [# S3 c
  wait-time ;; the amount of time since the last time a turtle has moved
! ~/ `1 O1 L; U7 U2 \! G% D]2 R7 o, k8 ?$ a: O7 L$ J
" h3 G6 G/ F) X# x! ~1 p/ s" P  |
patches-own
9 W' z1 B! r# N  _6 w- R" p[# h- T* J+ W& N  R4 u
  intersection?   ;; true if the patch is at the intersection of two roads
2 P; X2 m$ A' Z$ K5 t  green-light-up? ;; true if the green light is above the intersection.  otherwise, false./ T- z( F" M; ^
                  ;; false for a non-intersection patches.4 f9 ^; |$ F1 Y9 u- ]* J  r
  my-row          ;; the row of the intersection counting from the upper left corner of the
+ |8 z, `% d; u: |* z( V+ w$ z                  ;; world.  -1 for non-intersection patches.
/ U0 {2 X6 S$ J2 X5 \* `/ b  my-column       ;; the column of the intersection counting from the upper left corner of the
" [8 |+ s& i' o$ \+ Q/ Z7 ?1 p- k                  ;; world.  -1 for non-intersection patches./ W: k2 ?  s: G; N/ V( F
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.: ?7 o3 b8 Y4 y( [( _
  auto?           ;; whether or not this intersection will switch automatically.
/ i) q' p5 I  a3 H2 J/ n9 d" f/ X                  ;; false for non-intersection patches.+ \: E2 k2 x  R& i3 A- L
]8 F) r' p- M+ d, q  n6 ?

3 H/ @# H4 b9 `2 U8 E: h, \3 ~4 X) _6 W+ \5 e8 X/ J
;;;;;;;;;;;;;;;;;;;;;;
  g; ?1 A9 S: t2 t. S( u. p;; Setup Procedures ;;
/ s$ X, }  b1 P$ O7 Y2 q8 t( k;;;;;;;;;;;;;;;;;;;;;;
" ?3 r4 {" [; \) q0 I) {) M* ~1 @$ z. D1 `8 T# s+ O+ x
;; Initialize the display by giving the global and patch variables initial values.. F* O% ~( }9 F0 y. {( E
;; Create num-cars of turtles if there are enough road patches for one turtle to/ g# `! m" H& y4 l
;; be created per road patch. Set up the plots.
; \) E7 ]6 _9 B" S) `' y- fto setup; @: I' z6 l+ U: p
  ca
& J# Q; B- o0 |' o# n  setup-globals# c- h0 q* F$ b: J* x, b2 n# K

9 x" @8 T' j8 U" D. g  ;; First we ask the patches to draw themselves and set up a few variables
  T* k6 x4 S: O$ E$ r6 Q1 e  setup-patches
# v! f7 k' u' o8 N% K4 G  make-current one-of intersections
$ f7 P: d: V1 g  label-current7 K7 e% d, x& B# V% V1 S

" [0 K. m# N6 f$ Y1 F  set-default-shape turtles "car"
) D; u  L3 E% N# \& j) r8 v# c* ?' z9 |. k4 e
  if (num-cars > count roads)9 v( E% z4 \% F0 |$ H8 j, ^. d3 B
  [
% ?! w1 [5 A: @3 y7 D( B1 n) m    user-message (word "There are too many cars for the amount of "
" A- B- B' O- Q                       "road.  Either increase the amount of roads "4 K; s. s8 O1 t
                       "by increasing the GRID-SIZE-X or "
, [( g8 \6 g. g                       "GRID-SIZE-Y sliders, or decrease the "+ [" Z( g8 k* Y3 [1 x
                       "number of cars by lowering the NUMBER slider.\n"8 r# Y$ N/ ]; \& `9 f
                       "The setup has stopped.")
7 e# c/ b/ p2 b+ x2 Q4 k$ |% e# @    stop! t9 B1 @3 x/ W9 J
  ]& ^8 M+ x0 x  Q  r1 b

3 w" P% v* l; ?5 {5 T  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color8 }9 `, }* e9 \/ \% r& e
  crt num-cars% p: }) Z* D0 s! V
  [5 t$ b; Q& S1 X+ M/ O
    setup-cars' U2 n+ m! Y' d: j3 ?! h% {
    set-car-color
* G6 u" x2 ?$ Y1 n% M1 U% x. K: q# M: o    record-data
6 s. u& o9 E- k+ e6 ]  ]
* ?1 {, H4 h* s5 C. T3 h8 R$ r4 u. T
  ;; give the turtles an initial speed4 h6 l) B) r9 u; G
  ask turtles [ set-car-speed ]2 M  z6 L; g5 M) n
' a/ t( f' j) M% S& B6 \1 p
  reset-ticks5 ]$ Y1 q9 K$ s
end
' B; A& Q$ o5 x7 t6 `) @8 @* l* \7 V( b5 L* W1 @6 L
;; Initialize the global variables to appropriate values
5 o; J5 m7 E1 H$ r# l' Xto setup-globals3 Z! U3 V# M: m% ~( ^$ o( P! e" S: E
  set current-light nobody ;; just for now, since there are no lights yet: c& Y& L  f( d; s. g
  set phase 0
( G$ J8 E  Y5 w: t& h  set num-cars-stopped 0
& S- w/ M3 ~  O2 K  set grid-x-inc world-width / grid-size-x8 o1 \4 D' \, S, O3 N2 [' n
  set grid-y-inc world-height / grid-size-y: d- J# P; q) M  ^

& G9 G  X8 }6 d( \  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# T4 ]5 }- d" m. c0 }* @
  set acceleration 0.099; s4 t( d% {' N" z& [7 f
end5 g& ?8 K( J( ]! B% R

) _% s6 z* m- o4 W$ m;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
0 d; `/ |/ I4 O1 l- Q0 ~;; and initialize the traffic lights to one setting
  z$ W( V. U: W5 |8 Y% ?to setup-patches
5 c* f* m+ D) z! b8 Z6 g6 V. r  ;; initialize the patch-owned variables and color the patches to a base-color/ ~4 X4 w: L* r; j. }, \
  ask patches
# m. b# f5 G7 u; Y/ X. |  [
5 i# H0 I8 H3 I6 P1 D( T    set intersection? false
% ?! Y3 U! b: t& @& z$ s    set auto? false
" I! b7 c1 b% o& }1 z    set green-light-up? true3 p6 t+ m& N) g
    set my-row -1- C) h( b2 b( E* _2 F
    set my-column -1; s5 q& ?+ t0 P# K" i" ?
    set my-phase -10 n5 v3 D% O/ c8 ~+ q- J
    set pcolor brown + 3, B+ {: V" Z% j3 j  x: B
  ]! A; n5 G5 D% w4 l

1 f0 v. q' D+ `7 d9 g2 E# ^) r1 i4 Z  ;; initialize the global variables that hold patch agentsets
$ T: T3 i, r; y* M  set roads patches with7 u8 C8 ]( }) W* z3 c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: k8 p, M8 |+ }! o: t9 ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" a4 j7 _0 o7 C; _, v: {  set intersections roads with
" ?# i/ \& _7 x7 L  _    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ y: [5 v- r+ a5 e2 q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 T9 `. _% ^& D( Q% I7 \3 l7 ~

& Z8 ]  {4 B1 ]1 d* N  ask roads [ set pcolor white ]1 d' X7 v. s7 B: N8 g! `
    setup-intersections4 C2 k* {: N- X% E! D
end
" m/ U& Y. L, x. l: c. P' q其中定义道路的句子,如下所示,是什么意思啊?( z0 H$ l$ S: b# L+ ~$ X
set roads patches with' i( o9 X/ _: O, {' {8 H7 V: f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
/ g1 r" ]* M& A1 F: a+ D, w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]3 {6 q8 H/ ~3 |: {/ g
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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