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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。' z0 ~! v/ c3 L& d$ g  v2 ?5 G
netlogo自带的social science--traffic grid这一例子当中,
9 g# ?* U8 o: v: Wglobals
- r0 W5 s6 W8 l$ A: M[2 e$ m+ n( A' |3 {5 j$ F
  grid-x-inc               ;; the amount of patches in between two roads in the x direction$ F1 K; P5 _& f' x2 w9 @* O) O
  grid-y-inc               ;; the amount of patches in between two roads in the y direction7 d# P2 z$ m: {- G; \: x
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if. d2 b2 u" b& w% m
                           ;; it is to accelerate or decelerate9 j1 @. X% m! M& @" i( `3 L
  phase                    ;; keeps track of the phase
  F7 d( M7 u9 U7 C1 j9 O; f' T  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
2 q8 f+ |) b- F9 L% |1 c  current-light            ;; the currently selected light
7 K: m- j. H* w. E: T8 m% N2 @1 ?
1 |8 c; {0 t0 g2 c9 `  ;; patch agentsets' w$ [) P" X6 c1 ]
  intersections ;; agentset containing the patches that are intersections* v  n) h" Q$ H* @0 @1 B: p* I
  roads         ;; agentset containing the patches that are roads
" i$ s) s( {* z* ]+ `, C; ^9 N; w]
5 L) f2 P- O' Q- ~( {' F4 l7 ]4 Y+ a( e3 q$ r) A0 d
turtles-own
6 ~) [: M: `( O[
$ o! H) a" f9 H5 V' c. g# A  speed     ;; the speed of the turtle$ l$ ]7 ]8 Y$ L$ V# M, k2 K, Y  l
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right5 [# o8 V5 V! ?# g' c3 U2 Q; y! u" `
  wait-time ;; the amount of time since the last time a turtle has moved
  m5 W6 H. `+ N]
& y/ P9 ~# m4 U/ T, R# M9 M0 q. A+ @* s1 g
patches-own
: D7 h! c" [/ d4 r- S, g8 G' f/ n1 P& t[" C4 k0 U) W6 e) J
  intersection?   ;; true if the patch is at the intersection of two roads
; X) z6 A2 {' p9 e# y, z  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.* d. g. C, T, _9 \# V
                  ;; false for a non-intersection patches.0 m( r  ?- m7 d" O6 a' M1 T3 T
  my-row          ;; the row of the intersection counting from the upper left corner of the
6 G4 J" W- J+ u' d8 S: G% S  G# T( N                  ;; world.  -1 for non-intersection patches.
% I3 w5 j7 F. h. f  my-column       ;; the column of the intersection counting from the upper left corner of the
' E' X! T  ]- N                  ;; world.  -1 for non-intersection patches.) k5 W' h1 I1 [2 k, `/ j8 m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
9 w2 |" C. M7 K- f% o( H0 D  auto?           ;; whether or not this intersection will switch automatically.
: |7 ?. c8 p9 V3 a1 h6 U- s$ G/ M                  ;; false for non-intersection patches.8 g& U' R& M( l/ @/ ?( Q2 i! J
]
, Z7 H) `5 e+ q
7 k* z" I" W6 r* M' ?; r1 a& ~: K. Q* X1 k7 {$ Q! x- i: D
;;;;;;;;;;;;;;;;;;;;;;8 Z3 w8 n: X5 Y8 f6 i. i
;; Setup Procedures ;;
4 Z8 R, b6 B5 T% {5 n! _;;;;;;;;;;;;;;;;;;;;;;# ]; ~: }. i) K/ u$ B9 W- X
. V* _! d3 H& ~; h: h
;; Initialize the display by giving the global and patch variables initial values.7 {8 D4 |. H3 V/ a
;; Create num-cars of turtles if there are enough road patches for one turtle to
& o% p8 N4 R6 I;; be created per road patch. Set up the plots.
$ O/ _9 K6 V% _+ c6 K& k2 Xto setup
$ [0 T) h1 L3 C/ _- l  ca- `5 `: X: q8 W
  setup-globals
* j. t6 s( p+ e$ p5 F8 h8 n& |! ]+ c0 E: B" s2 F3 W8 W
  ;; First we ask the patches to draw themselves and set up a few variables; G6 \5 N. h0 o! `4 l
  setup-patches. G! G. c0 c. l8 q# C
  make-current one-of intersections
5 Q1 b/ }/ B( }# y$ R) ^* x0 k  label-current
1 k! W) U$ E1 @8 ~0 O
/ O5 Y6 O. J  ^- X  set-default-shape turtles "car"$ q0 Y( [& @1 L/ ?' L9 n4 c" |/ m
5 R9 {& y6 n5 U' y% B6 P  U9 X
  if (num-cars > count roads)
2 ]9 ]' U, A) a3 `3 C  [5 B" L; S' k+ p- t: C% V+ v" q# i
    user-message (word "There are too many cars for the amount of "
9 L2 K. N$ D  t- K$ L                       "road.  Either increase the amount of roads "$ [' D% f4 P  G
                       "by increasing the GRID-SIZE-X or "
* v, s8 v& A& G  J                       "GRID-SIZE-Y sliders, or decrease the "
" C8 {, t' V& u% Q% `$ S                       "number of cars by lowering the NUMBER slider.\n"
3 c5 |: [) P$ E, Z+ V' i3 M& v* B                       "The setup has stopped."), ~3 v9 ?6 o( g$ ]0 f$ M
    stop6 W& e2 x, H: g$ h' ]1 _
  ]/ [+ f! J  p. \- g& E1 i
" F/ D/ z  x' j3 U0 T
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color& P, F6 Z- `: X
  crt num-cars! _8 D9 @' h2 f
  [
2 m/ q, q1 Z' J0 o/ y    setup-cars5 ?0 C- u8 s: c* x' p/ l
    set-car-color
0 ^" i2 ?. p+ X    record-data' r) S% z3 V+ O5 b# x. y
  ]) h7 S$ i' {" i  t  J
' i# g! X/ K: n8 ?6 w  w& Q; `& b" R
  ;; give the turtles an initial speed
' \: n5 M# l9 H  ask turtles [ set-car-speed ]& y7 a5 J- Q7 J) Y
1 d# U  i, w1 h
  reset-ticks1 `% L/ c& V) P1 m" r3 C
end* C* a% Z4 `  I; c8 c
, D2 m# ]7 I/ P
;; Initialize the global variables to appropriate values
) e: x% E* M6 s$ I; A: r* G% T" wto setup-globals) h& K$ D/ c& W  g
  set current-light nobody ;; just for now, since there are no lights yet
" @# W$ V$ z# c, X1 \; B  set phase 0
) k! q; P& i: U1 [  set num-cars-stopped 0
! N0 ?1 r, U$ m( O& P" U/ L  set grid-x-inc world-width / grid-size-x
9 {  t  t$ M- Y5 Y: Q; X; [3 W5 C$ `  set grid-y-inc world-height / grid-size-y
5 ?* B5 E# }8 P, I2 g, G' n- s$ b- B
2 L( y# l5 L' Q  x/ k& G2 C- ]% E  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
! \4 M. [! f6 e+ v: D. H  set acceleration 0.099( S/ }& D3 O$ O1 I- i% ?8 J2 r
end
, m# q) d/ q2 `
5 E* V+ k$ _* Q) `$ J9 ];; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 x& G4 w% r: u1 m! x) j& U( |;; and initialize the traffic lights to one setting
5 k! L; L1 T5 F$ @! _  ]to setup-patches
+ d2 t  S. c/ J$ O0 H* M% t  ;; initialize the patch-owned variables and color the patches to a base-color
3 w* X% S$ l+ p- L# P  ask patches& t" K  }$ H4 L" H
  [
7 F0 X# y7 W- l    set intersection? false
! W( t4 Z4 v# K, O    set auto? false+ a* f+ _* l, R) k" ?) D! K
    set green-light-up? true
# E+ b4 A1 X3 ?  i( h    set my-row -1
9 ]  ^, q1 |) ^/ j    set my-column -1( [; I4 L+ P" z4 u
    set my-phase -1
( }' P8 f- J, F    set pcolor brown + 3
$ c- H, a: L7 z  g3 g  i4 D1 U: p) a4 \  ]
3 [$ Z  o" R( e% `; ]' o; g
7 T' ?7 B# \9 h; ~- H1 [  Q" u, G  ;; initialize the global variables that hold patch agentsets
( y9 e3 f& |6 s  set roads patches with
) q/ R' V; D; S    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
0 P8 c8 s& h" I    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 P& \' j) `) x) k' F( `  set intersections roads with% J3 ~1 c  D  w$ [. U  F& P
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
6 F1 w( S8 F1 N; x    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 N3 Y! Y9 h) b& N8 b  k! B

* v+ ^: M  N5 u6 ]! Z( {  ask roads [ set pcolor white ]
. n1 M  c" ]; ~0 D/ i; q9 l    setup-intersections1 Y9 S- l' s$ l* q) K# R9 n
end' R/ h4 e7 S  v$ i+ h
其中定义道路的句子,如下所示,是什么意思啊?* Q3 S3 N' V: w/ @
set roads patches with
; T7 ~# @3 q  z4 o8 q: m& O    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or, n; O/ B' c4 |5 v( ]/ O3 i
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]0 c' o8 \* x7 P& e
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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