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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。
( J( Q% M: m: d; ?9 F% p& ~netlogo自带的social science--traffic grid这一例子当中,% }' ]7 K: Y6 `! G. A
globals
, x' ~0 N$ M: v; @  R0 Q0 T[
0 k+ T( p# A0 [* p  grid-x-inc               ;; the amount of patches in between two roads in the x direction# ?9 C8 `9 L/ j) y) s
  grid-y-inc               ;; the amount of patches in between two roads in the y direction5 d: B8 ]5 X. \9 i/ U! B0 G
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if, i$ g+ p# |* p/ r- q
                           ;; it is to accelerate or decelerate
& s& P! h1 d8 R1 A( \  phase                    ;; keeps track of the phase* m6 z. S# P0 c
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure) u* K6 \9 c. t* I1 _0 ]* v
  current-light            ;; the currently selected light
/ D' T9 [3 z# |- ]3 [, }1 f3 ~" h& F$ `3 |  o5 H& J
  ;; patch agentsets9 U1 o# p; l! o% ^8 v( }, H
  intersections ;; agentset containing the patches that are intersections$ V' e$ s- j3 M) ?% w2 K
  roads         ;; agentset containing the patches that are roads
/ w; P0 |! K1 A% E" R3 `]% Y. j" [7 Q. e! m% J
7 T) p' H  a9 L4 N) C* }" H
turtles-own0 x3 ~6 K- L! P. ?
[
2 L  Y7 C+ g9 i, O$ _, B: V' v  speed     ;; the speed of the turtle
. Q' w! x8 x: q/ m( H  up-car?   ;; true if the turtle moves downwards and false if it moves to the right! |( ?0 g& @' m0 r
  wait-time ;; the amount of time since the last time a turtle has moved3 D5 d8 c4 _! s* d9 T5 g
]8 k9 q, R; i1 R/ o! T
% e- N2 {" g5 V
patches-own& T: U* ?! z) F0 L& X5 ^
[
, O. H0 `' @* Z/ X  intersection?   ;; true if the patch is at the intersection of two roads1 w. f4 p% g0 Z$ f/ s* X
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
! M5 v2 t0 L; R: i/ @. S                  ;; false for a non-intersection patches.. u9 l" N; c2 |: ^# u% _# D
  my-row          ;; the row of the intersection counting from the upper left corner of the
- W) Z$ w' f3 }% {                  ;; world.  -1 for non-intersection patches.% N$ B4 J  a+ G# y( n7 Q. \  e. j
  my-column       ;; the column of the intersection counting from the upper left corner of the
3 U5 h  I+ P+ {, d/ f2 v                  ;; world.  -1 for non-intersection patches.
, S+ k( o1 f" T$ Q/ Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
0 O% l1 y8 R" g2 X  auto?           ;; whether or not this intersection will switch automatically.# ?" z1 a: `$ [6 P
                  ;; false for non-intersection patches.
4 m" |% c' f, b7 @/ {( M) P4 ^]
! i5 N7 ]7 s, K& b$ Z
1 i7 G  H) y$ o+ y' L" ~7 K1 x4 d" T0 c+ C- q
;;;;;;;;;;;;;;;;;;;;;;
0 B' T; J2 v6 Y$ \5 G$ |* [# G! m;; Setup Procedures ;;2 o* t! [+ @8 i8 f8 g# K
;;;;;;;;;;;;;;;;;;;;;;+ W1 d9 Z. O/ }0 ]
, u, p  W  d. t2 X
;; Initialize the display by giving the global and patch variables initial values.
4 ^: ^( C) |6 g1 O. I;; Create num-cars of turtles if there are enough road patches for one turtle to6 l, Z9 y9 n- t/ N( ^- O6 q8 o$ X5 k
;; be created per road patch. Set up the plots.
  d5 l* y9 M9 i) J* I* Nto setup9 r0 _& m+ F- I' ~/ H# m6 A: C
  ca/ z) _' X) A- t  j  I* j; o
  setup-globals
+ ~, T+ ]" A$ w
4 z  g/ K) e7 X! z% {8 t  ;; First we ask the patches to draw themselves and set up a few variables
- U" H* J* X* u+ Z5 p  setup-patches
0 z" u8 c+ n* d  e( n* @  make-current one-of intersections7 q( s' x, g, ]" I; m
  label-current! b. z1 m; D  F! U& x4 y

1 {6 v' X# H6 F- Q) X4 Y; _  set-default-shape turtles "car"( @6 t" R% T) J& s2 @- s

6 d* h, t9 n1 l$ T  [: u+ w; ?* ?  if (num-cars > count roads)! m* ?: f7 v, F/ y! p
  [
3 j+ |- L  I$ O1 ]    user-message (word "There are too many cars for the amount of "
$ R4 A  V5 ^; D, `4 d4 V, c                       "road.  Either increase the amount of roads "
7 c2 j" q2 l" N. n                       "by increasing the GRID-SIZE-X or "
7 P1 r. `6 }; R# ~# ]) D                       "GRID-SIZE-Y sliders, or decrease the "
2 I0 c* f: \. U- W! V/ N# C$ v                       "number of cars by lowering the NUMBER slider.\n"4 D9 ~" u" R7 ?4 N" v
                       "The setup has stopped.")
5 R+ _% A+ ?2 F# q9 M* O    stop! W1 \* N& ^7 ]' A1 y! r' {
  ]
; e; B8 O. W( L. v4 z" v) S4 c+ q6 @" A! b& j2 E/ H& z; T" L
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! W* T5 q( `0 f( a& h
  crt num-cars
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3 Y8 I$ b  X- g6 \6 [, V    setup-cars
2 Q% b8 T. F/ m* }8 U+ |: }    set-car-color
$ f2 I; t7 K2 ~) A8 Z9 ?* D    record-data
& V; K6 w, k% G  ]$ x' G8 n3 K7 E2 B2 L5 {. ]8 G

! P1 R5 |9 O3 T/ G$ i  ;; give the turtles an initial speed
7 r2 v  p& Y( n/ q  ask turtles [ set-car-speed ]
( _; Y. v: Z( a$ ^. b+ N( Z1 r# U7 ?2 z8 V
/ j0 Y8 w5 v. L% h: d3 w$ H  reset-ticks4 a, z- t2 z2 _, _$ e
end
- C8 o  q% _6 m' ~% ?6 `; |  _/ w; V1 `4 H# o* v
;; Initialize the global variables to appropriate values
2 v0 B( Q& L" `$ _+ ?to setup-globals
" p/ y  @* m+ Q6 g! N) u  set current-light nobody ;; just for now, since there are no lights yet
6 X9 A% P  f% q* w- S" f$ g) ]  set phase 0, e4 \3 a( ~% D2 T9 }
  set num-cars-stopped 0  y3 u( N  F% |( `* `
  set grid-x-inc world-width / grid-size-x& ~' }. ]7 x- ]1 c: }
  set grid-y-inc world-height / grid-size-y/ B. r: b0 ]" N* X2 P
1 A7 [, x( r( m. r: @
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
7 s! F9 m& \0 c. c; `8 S( _2 h  set acceleration 0.099
% A( f/ J5 r) m* I9 O& g1 G  Fend
" @# w" f8 E+ a
5 ^8 c; ?+ h6 _;; Make the patches have appropriate colors, set up the roads and intersections agentsets,. A( |. |+ A/ c; {- j
;; and initialize the traffic lights to one setting
1 k- |1 L1 X2 Hto setup-patches  g7 i* Q$ W+ O  n, h0 @" z* n
  ;; initialize the patch-owned variables and color the patches to a base-color2 e. E/ z; Z2 o5 c# \9 G/ N
  ask patches
; O. m# N$ ]5 {, Y9 E7 j6 I& i  [9 E" J9 s: A! o% m
    set intersection? false" g9 ^( Q8 I) h0 ?$ N
    set auto? false
5 l% d' @3 Q, ^    set green-light-up? true+ s# H' W  }/ p) D/ C/ |
    set my-row -14 \9 H% I1 ^7 O+ w: @
    set my-column -1
: ?  z* I' W4 l* R. ]& S+ m    set my-phase -1
- I4 _2 e2 q7 [# a    set pcolor brown + 38 J- }) K# m5 i; N4 {3 g
  ]
5 s$ H5 Q, k! M' y2 G
+ r7 \6 }6 w2 }& x5 N+ K- b( t  ;; initialize the global variables that hold patch agentsets  V5 r7 ]! m, N( j  v; A
  set roads patches with# S' p( ]+ i5 I3 l2 ^) R8 h
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
! S: B- H5 v9 o6 p3 J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 v8 P+ h+ Y9 R, e  set intersections roads with
8 F3 ]1 K' M- {% L: u    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
& E( t; g. M8 K+ T    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]% m" [; p  w/ [
6 K, t/ \* S' T* P( Y, H/ X: Y
  ask roads [ set pcolor white ]
* x& d' E5 r. z8 E% i1 D    setup-intersections
0 W$ \: t$ p& r$ hend
& w% x, D& t  Y) i1 a其中定义道路的句子,如下所示,是什么意思啊?
9 t/ g2 l5 K/ d1 W set roads patches with! G+ q3 G, u" T" k1 _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 Z" w. D7 F7 ~8 A    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 x2 n$ [$ j/ d- v  H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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