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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。) K  S' z6 ^- ?
netlogo自带的social science--traffic grid这一例子当中,
" x$ T/ g. B# z0 y  I9 F$ qglobals! I0 {$ Q" |9 x; m: @" t
[
- a. _; u3 S& r8 j5 ^$ o, c  grid-x-inc               ;; the amount of patches in between two roads in the x direction- m% {/ Y8 [8 o( \
  grid-y-inc               ;; the amount of patches in between two roads in the y direction+ G# D1 n! U: D- \2 J+ ]
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
. F7 Q6 X9 R, m! M6 N) ^: W                           ;; it is to accelerate or decelerate
* {: E/ p  A' h9 C4 d6 W3 b  phase                    ;; keeps track of the phase6 x- a! R, w' u9 i! S$ |
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure4 p: z8 d3 f8 _8 Q8 y0 B
  current-light            ;; the currently selected light
/ U3 s) `/ s# w0 q1 a$ _
+ d( @1 W( A  m; n5 F  t  ;; patch agentsets' c$ Z( m, W. R$ E/ G
  intersections ;; agentset containing the patches that are intersections' `7 f1 M2 X0 J, T
  roads         ;; agentset containing the patches that are roads( m7 C) ~1 w/ q- @1 w
]
0 g2 L' [7 O# X) J: g+ I) }
7 [$ @" _2 e+ x  U0 oturtles-own! M; q. x' ^, x9 ]4 ?1 z3 N( w
[
% z/ `+ x0 X7 r  _5 j9 p) Q: o  speed     ;; the speed of the turtle
9 Y: |' R$ W0 G) }9 p  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
% W) _2 Q' b' R! I  wait-time ;; the amount of time since the last time a turtle has moved# a. C& W5 R+ i! |1 Q% S
]
# ^! G$ u8 Q0 u5 l) K
# J$ l7 D9 v- }8 x+ a: u, Rpatches-own- a* A2 o$ u7 Y6 }6 M# D' v! C
[
4 }4 X0 [' z- d. Q$ V# U  intersection?   ;; true if the patch is at the intersection of two roads; u: I8 X. r2 {% @  _
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.% j$ S# M3 _9 l) [) C
                  ;; false for a non-intersection patches.
; H; ]8 n- ]. @) n7 Z8 T5 q  my-row          ;; the row of the intersection counting from the upper left corner of the
% k' h" s3 R3 f                  ;; world.  -1 for non-intersection patches.
  J7 \2 P3 h' c% y- _) K  my-column       ;; the column of the intersection counting from the upper left corner of the5 d& s- R5 L1 z: s9 h
                  ;; world.  -1 for non-intersection patches.
- C1 b" t* Y! b( o2 u* g  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.% T- h) P9 l" K# u
  auto?           ;; whether or not this intersection will switch automatically.
3 J, R% N8 {$ E; C                  ;; false for non-intersection patches.: |  H, c  H: @+ r- B
]
  d- H4 c" ~3 e" R/ N+ u/ m! F! W  u& W: v

1 Q/ M( Z4 W& u- V. l/ B;;;;;;;;;;;;;;;;;;;;;;
# [7 b! A* X# R7 [3 f;; Setup Procedures ;;: W% W5 `- Y$ _$ E
;;;;;;;;;;;;;;;;;;;;;;: [. N6 E/ x: b9 E" f

8 S( ]$ S, |1 e* ]  x/ d, I; o;; Initialize the display by giving the global and patch variables initial values.% v% @% w( l5 P5 O# F' n
;; Create num-cars of turtles if there are enough road patches for one turtle to
0 x; R4 Q% d; a;; be created per road patch. Set up the plots.
3 O+ [' c2 ]1 ]/ {6 Y$ fto setup
5 {, _; ?- K/ V' w2 z  ca
+ N9 B4 l' Q% e  setup-globals4 ]6 M1 w/ v$ M
7 r' K! E& h) B5 T7 z0 A% `
  ;; First we ask the patches to draw themselves and set up a few variables
& j+ g+ \2 @4 L) _. C  setup-patches, m' ^, d3 P  a' i5 G9 Y
  make-current one-of intersections9 V& D, O$ P8 q% S5 l8 S/ [5 t
  label-current
1 d2 f! W7 ?( P" B+ |7 g7 q; E: g+ z2 q2 z
  set-default-shape turtles "car"' b, o% E$ Y+ Z/ k4 P: o
: a7 h& J  R& {; |5 Y
  if (num-cars > count roads)6 e+ G, d/ t/ X2 r  U
  [0 w- a2 [: u& U9 S8 x
    user-message (word "There are too many cars for the amount of "
' _7 A) o* F3 b5 g6 _0 Q# G3 r                       "road.  Either increase the amount of roads "
- F( J; `- y1 V9 F1 e                       "by increasing the GRID-SIZE-X or "
* ]3 Y0 [" ]2 F0 N! X6 C0 K                       "GRID-SIZE-Y sliders, or decrease the "
5 q4 g! c6 J2 o) i                       "number of cars by lowering the NUMBER slider.\n"
5 f+ |+ E) `2 c" h3 q3 Q* N                       "The setup has stopped.")9 k1 Q9 ~, o& E
    stop6 K9 i6 ~/ N1 o+ [+ b! ~
  ]
/ q6 _3 U" w3 K% [7 _# T0 p# Z, v! o; h* o' v) g0 g/ j* t
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
( U9 F3 }4 {; a% z  crt num-cars) z- `/ g" f) J
  [
3 ~9 A) F$ T  X, J; i. n2 e    setup-cars
& J. a1 `* j' E; C2 L  f$ T2 ~0 U    set-car-color
7 H6 a) G; G& T# L3 w1 m, B( d    record-data5 n  c# Y7 X5 x- M& B  U
  ]
. Z* m  ]& B( u+ B! C% b. W# l
8 r" B; r6 e# y1 i7 M  ;; give the turtles an initial speed
  H: j0 `; s0 U5 }( O) i. V; d  ask turtles [ set-car-speed ]
" t6 ?. L/ G9 x  U3 N1 F' @: K+ t! q
  reset-ticks
; `) [- T- I4 M( F& Tend# I  O2 T9 o7 L- R  [% A
! b+ }! {! \& l3 q& f& ?5 [
;; Initialize the global variables to appropriate values
' l* b, l1 {! zto setup-globals
# N7 U9 J# Y/ T" ?  set current-light nobody ;; just for now, since there are no lights yet2 S" K) h$ Z4 Q3 Q% H
  set phase 0( c+ l5 m% S4 r, m/ i% s/ d
  set num-cars-stopped 0
- t& y$ m0 O, G2 O& A3 d  set grid-x-inc world-width / grid-size-x
9 H5 }; m' {9 q. x  set grid-y-inc world-height / grid-size-y, ^8 w- |0 m" s. s1 u

" N% r0 p0 H' h8 O0 L  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& I4 T  ?, B1 h  set acceleration 0.099) d' ]) \* ^; s# S  t
end
1 E' w" g% @1 P! w* G# Z8 M) z/ ^: R8 n* ~7 u) V/ N  N; S5 Y5 G2 L2 i
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,( h, X# ]+ O& j. u' R: V  @+ Z
;; and initialize the traffic lights to one setting
% a/ O$ J) e) b# C5 @' _3 uto setup-patches9 y/ E$ y( O4 T# X8 B
  ;; initialize the patch-owned variables and color the patches to a base-color  P0 f' o5 p, ]0 o+ G' Y; M
  ask patches
9 O" {1 |( H3 Y0 Q( E, O  [
4 X) [8 {' t; o    set intersection? false
( {, W0 C% i# ~    set auto? false7 ~2 \( _+ u% o  `
    set green-light-up? true7 C8 I; x6 W5 e- D6 L7 |2 K7 y
    set my-row -18 V( I: k, _8 d; T) Y0 D- }
    set my-column -1
1 x- r2 B- |2 r/ y4 [, x0 o1 `    set my-phase -1
1 W, }; W2 C. Y' o    set pcolor brown + 3
' T7 N* y8 a4 E7 f; k  ]4 j4 G: Q. h! t. P. U3 M$ v0 B" B

8 U& P+ f% {; Z3 f2 H. c, E9 C1 ^  ;; initialize the global variables that hold patch agentsets# a6 e- n  D# N3 x5 V" ?, z( x8 g
  set roads patches with
* t5 Z4 X8 m8 ]! J) T) f/ ^$ `    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 g% y8 \& z: j2 a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
" \% I( ^8 b2 N3 ?  P& O  set intersections roads with
0 l9 h- l0 P( m; q0 z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and/ \$ ^* B8 D5 }
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% ^' |4 C2 M. B' t# C) r3 W
4 l5 `9 \. s- Q( t  ask roads [ set pcolor white ]
/ k8 V8 R# Q1 q0 O    setup-intersections- b3 w$ S* R- l& x- E. I2 S
end. b8 E; ]; z, q+ F& m- [
其中定义道路的句子,如下所示,是什么意思啊?; _& E6 T' M& G* H
set roads patches with
& T0 }2 {9 @! g  z    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
, R$ T3 k. i1 u) Z- k2 q    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 w( `5 x  j( M3 d# k
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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