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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。
9 ]+ F4 A# T4 F; ?; H! Z3 nnetlogo自带的social science--traffic grid这一例子当中,
! Q4 B1 L9 L, y% g% q6 `# o; eglobals# ?2 Z; D$ a+ t+ u% O& D
[2 }# `( [2 @' R5 I2 ~3 y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction* R  j& n; Z8 ]. U8 ]
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% p0 x! }1 c& o$ H* c! e- U  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
* S8 X* I! E6 H$ m8 z+ `. t                           ;; it is to accelerate or decelerate  p8 _6 a1 c7 V
  phase                    ;; keeps track of the phase
# O! a+ W4 O: ~: P  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure% L- ]' U( `( M) e5 N
  current-light            ;; the currently selected light
$ h+ P& z2 ]5 T9 g8 O3 Z) z+ e& a0 b8 L( G* f* W
  ;; patch agentsets
- C* I5 X& N3 c2 g  intersections ;; agentset containing the patches that are intersections( R0 K  l% X- X) ^& t
  roads         ;; agentset containing the patches that are roads
0 e! [0 V1 o, {; c8 m9 M; A: ^]
% F/ e# ?% i( Q1 C" k& h; ]5 b) Y5 h$ E
turtles-own
2 L1 F" \. m/ J& C7 b8 K+ W[6 S: R" U3 E$ l
  speed     ;; the speed of the turtle
0 r* w7 m5 Z) b( X& g  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
. h7 g$ \0 J0 \$ w! Y- c  wait-time ;; the amount of time since the last time a turtle has moved& k' a: Q; j. z8 N
]: W- v: c" b5 t- t$ y+ [3 T

$ V! ^: [6 I$ v! Upatches-own
) X, ?. o- W' v% `9 b8 V& {% D[
. t6 A* ~7 J$ L+ Q# H5 z  E7 p  intersection?   ;; true if the patch is at the intersection of two roads
* t" R! X0 I9 Z% A- c  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
2 m; y' \. N/ }+ C+ i7 r7 `                  ;; false for a non-intersection patches.% m" {/ c% l/ i7 x* m  d4 |# m, Z  c
  my-row          ;; the row of the intersection counting from the upper left corner of the" v! C7 c% }' L9 E4 r( I8 q
                  ;; world.  -1 for non-intersection patches.
3 K; K- v; A+ V6 i# _" c  my-column       ;; the column of the intersection counting from the upper left corner of the4 S+ L; i7 L/ T* z
                  ;; world.  -1 for non-intersection patches.
5 {$ J0 k' R; {" [9 c$ |  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.$ A* H1 W) `7 e" n
  auto?           ;; whether or not this intersection will switch automatically.: h1 g: }7 w  ?
                  ;; false for non-intersection patches.
' d+ n0 W, d- E( L$ Q+ Z]
) z+ e; x2 @- L  @7 _. ^1 R% t/ W

: ~( a6 b4 V1 T# v0 w  s# J;;;;;;;;;;;;;;;;;;;;;;
, j9 r# W9 x, m' ~: o9 }' L;; Setup Procedures ;;  }* m3 J/ x; Y
;;;;;;;;;;;;;;;;;;;;;;1 V5 t# h/ t' H% {1 N
2 j# C6 P. M+ z# |3 k
;; Initialize the display by giving the global and patch variables initial values.
+ G! A( p& X; S1 ^( k;; Create num-cars of turtles if there are enough road patches for one turtle to
7 d, f2 A/ C! b. F' p* `;; be created per road patch. Set up the plots.: W( d  Y( L; a
to setup* Q, a( t* a6 H
  ca0 ^2 b. p/ H7 @( _, N2 {+ Q9 V
  setup-globals
1 n+ }5 ?) b1 Q2 @8 a
* k* f- Z7 C2 p, c7 O  ;; First we ask the patches to draw themselves and set up a few variables
5 ~' a/ G& {/ }  setup-patches
. b1 \: q7 t+ v# N5 t  make-current one-of intersections
0 L8 Y8 ^0 k$ W" t$ \0 P  label-current) a2 j0 G/ {( y( x, N0 u. P

7 s; K  K/ G# ?, [  c  set-default-shape turtles "car"
" l2 ]: L8 B' b% g9 t. n, {
( D; B4 L$ v+ X5 _  if (num-cars > count roads)- U9 w7 `/ m: k, F0 S+ p- T
  [
' g" M  c0 F% }    user-message (word "There are too many cars for the amount of "" O! b  }% n# X7 m
                       "road.  Either increase the amount of roads ") \+ L  U3 n8 ^% j$ R/ {8 e& F
                       "by increasing the GRID-SIZE-X or "% h8 x3 p$ [+ v, S, m
                       "GRID-SIZE-Y sliders, or decrease the "# L) P( f7 X1 h  a% y8 Z9 E/ l
                       "number of cars by lowering the NUMBER slider.\n"" e" e7 y* F1 F* M6 o5 W
                       "The setup has stopped.")" x$ A, N$ ]( C% _
    stop
' [5 Y$ @$ z( W- u& A7 b  ], G3 a, X. O3 u" @; a/ S& x3 U+ @0 X
5 m2 G8 J; H6 a* d3 s
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
* ^# u' r8 T" g3 j4 k+ [4 _; Q  crt num-cars. |/ ~+ x1 O; D" [/ |
  [
5 g" v- G& y5 I    setup-cars& r$ z" W8 Y  t# ~- s
    set-car-color
1 s$ Q. ^# Y( ~, x1 x$ A& f    record-data
+ S# C2 K, ~" V. u" X  ]% e1 l- ]9 }( Z  E
8 B' y# N# h* ]3 q
  ;; give the turtles an initial speed
. ^/ Q1 G& u' c/ p% ^9 V  ask turtles [ set-car-speed ]
$ ?9 s6 W. R0 G) A5 Y* B" M
- R8 y5 @2 O6 K/ _% Z+ n; j( v  reset-ticks# J3 X$ `2 M1 T- q: i% ?& P; ^1 [
end
' I. r9 c, v9 E3 V% m
3 m: u7 z- X: }$ G8 |;; Initialize the global variables to appropriate values
9 q3 D. d* P; \# z) I( A$ G7 D( l7 _to setup-globals
: T9 c' K: l( D+ ]% u# Y  set current-light nobody ;; just for now, since there are no lights yet
1 n5 G5 X" w" y& j; ]  set phase 0
9 A' w# _0 z7 N$ Q4 ^$ r  set num-cars-stopped 0
0 B, h/ L3 f& |1 \: A  set grid-x-inc world-width / grid-size-x
0 B' v+ s3 B6 h* Z. B2 w, T  set grid-y-inc world-height / grid-size-y
& b, Q& p6 S. o3 E0 |# }  L: ?! {& H- Z) R. z
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" w6 [) x$ O* N4 @! m5 p% |% q  set acceleration 0.099
4 t! K$ G7 ]2 i& U) n4 Q, ~( ?" Gend" k9 R* ]1 x9 r. F  f

% t+ g9 {& p# Q0 [$ @+ Q, b;; Make the patches have appropriate colors, set up the roads and intersections agentsets,4 X1 S) _0 P* ], `  h
;; and initialize the traffic lights to one setting
& l% e7 |2 V& c7 e7 ^* R& Lto setup-patches
; D9 z, E, h1 ?' w0 v& E6 V$ g0 x' n  ;; initialize the patch-owned variables and color the patches to a base-color
! i6 p1 k. z+ Y4 W) Y. [  ask patches
9 L) q- x3 \& ~( S5 j3 I  [4 M4 l3 @" g  R' Z% _/ E  @
    set intersection? false0 u; {. j5 q- h  l+ o2 _
    set auto? false$ l) N2 [% Q7 i  ~6 ~% m; O
    set green-light-up? true
) B3 C5 s  Z7 f6 h6 q    set my-row -1
" G* U: T" M5 H; C, L3 V    set my-column -12 {7 s2 {0 M2 M2 F( v5 T
    set my-phase -1
  K$ q4 _, r$ t) Z8 V" @" o0 ]    set pcolor brown + 39 q: `4 r# g- k& ?5 n; n5 n+ S
  ]
" e$ f8 |! W+ \/ d% M4 H: o" x
, U# X; n  t6 D1 X& M9 S! [  ;; initialize the global variables that hold patch agentsets  u  w( a3 c( \% u
  set roads patches with; {5 r' r; i$ z) V* A$ c: Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 B4 W; I* H. }0 r  a8 g    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]. C3 z+ ^( Q! @& @- P
  set intersections roads with, A* a. S5 B, S
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
$ {: [" t5 |7 }8 c8 n" {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
4 w7 c  _, O7 N, D
8 g* O; P8 h! @  ask roads [ set pcolor white ]
: }, h, s) P# P4 {    setup-intersections
/ ~& z7 M) s. D  Lend' s, c: }! }1 a" d+ U0 ^" G2 f
其中定义道路的句子,如下所示,是什么意思啊?
2 M8 c( H  b$ x* k+ J+ H set roads patches with
* {% p% t% T0 a, [- h: m, I' S$ [    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or* ~) c9 s! x5 G$ {/ y* C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  y2 ~! m8 g9 J4 O+ n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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