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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。+ c8 T& D; S8 w7 O
netlogo自带的social science--traffic grid这一例子当中,
8 p# q5 h( `  Q) U; v! Xglobals
- O* F, i+ \0 ^; ?! {- O[
1 `+ k; n  V  h1 d/ H  grid-x-inc               ;; the amount of patches in between two roads in the x direction1 b) R. U9 Z( W0 E0 Q/ E
  grid-y-inc               ;; the amount of patches in between two roads in the y direction9 ^( v$ G: z) S) i' X
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
4 m0 ^3 ~. o% v& A% N0 @                           ;; it is to accelerate or decelerate
  t6 `4 ~% k6 r3 B- V  phase                    ;; keeps track of the phase, [9 ?! p4 q* O! j% j; f/ ~
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure0 N7 y( v% |+ A) A1 o4 U
  current-light            ;; the currently selected light
* s$ d( K0 }7 V2 _8 n1 S
3 e* ^6 s. F' e8 a  ;; patch agentsets
$ F# R& K* p* s- v* I  intersections ;; agentset containing the patches that are intersections  M+ c" e' p6 ~3 |$ n
  roads         ;; agentset containing the patches that are roads
# \, R& L) q  H# z) [1 C]# k: @1 T' Q$ G% i8 h

6 A' }9 D, d! q( c6 s  W" I8 dturtles-own
8 a6 o6 s- U- W$ A4 P5 M[& l5 h9 ^+ ?9 d9 r: [% h! ]
  speed     ;; the speed of the turtle! f7 Y; l( f" M2 B9 V; e+ R( a
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
5 ~, @/ {& i. p) m) D9 N$ M7 A  wait-time ;; the amount of time since the last time a turtle has moved
+ u1 `3 i, n2 L/ c' ^/ n]
5 C1 o/ b- l# b" q" d. r# D7 l" A2 s0 Y6 u  Q- `  ]
patches-own
4 B9 R1 }2 |% `* c7 U[  A' f2 U. m, k( |9 W# H
  intersection?   ;; true if the patch is at the intersection of two roads
4 C$ s/ q9 `" E  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 ^7 ?( I! E0 n) C7 O- A                  ;; false for a non-intersection patches.# [# J% O5 u# @
  my-row          ;; the row of the intersection counting from the upper left corner of the7 O3 J! M5 E" r5 p) X/ h  E" V( M
                  ;; world.  -1 for non-intersection patches.
/ W! E, |1 Y' e! t+ h  my-column       ;; the column of the intersection counting from the upper left corner of the! d9 U% [: @7 Z9 x! i" @
                  ;; world.  -1 for non-intersection patches.
) h1 m! u$ W( Y; @. B  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
! K4 v* m2 G! D0 ~  auto?           ;; whether or not this intersection will switch automatically.1 K1 Z% X1 B) v/ @5 \
                  ;; false for non-intersection patches.2 s2 v! P. n3 @. t* s1 d  [
]
- o5 c# h* \3 U+ i5 E) ~
. q# A4 f+ y1 Y, U+ W) K* v7 ?( i" s5 ?. u. x7 N: u
;;;;;;;;;;;;;;;;;;;;;;
' x$ |5 W$ N8 b/ j% J0 ]9 j;; Setup Procedures ;;
- q* C% x! |* u  w;;;;;;;;;;;;;;;;;;;;;;
+ o: `# x. q4 S1 t% [/ q$ l/ U
: S4 V8 Z: M# i4 F, I8 L: R) p& Q;; Initialize the display by giving the global and patch variables initial values./ T  ]+ Z( G1 Q) l6 i* [% ]
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 k, _6 S' H' x- r; P: w5 \;; be created per road patch. Set up the plots.
1 f+ |& \0 c) A# c& {0 Hto setup3 m9 |8 |1 \& e3 t/ Z: M
  ca7 s  E2 w! U2 S1 ~
  setup-globals
, G% }3 t6 W# n
; p# s4 T# W. e: S) K% Z  ;; First we ask the patches to draw themselves and set up a few variables
( S) k' ?7 u% h7 G3 p  setup-patches
5 D/ C- P! R& _* ^$ ^  make-current one-of intersections4 U2 i0 i' j4 D
  label-current1 F' }. Z$ j, Z7 K$ Z  h

0 F& @4 }; h/ w, S1 W/ G: E  set-default-shape turtles "car"; V; m( Y3 Q' r. L, z& n

1 s% X; ?5 o# P9 B" C: t" [  if (num-cars > count roads), G, T; M) K" Z5 v" p; ~) s
  [
( k8 [( ?" e+ w; M# _" k- S+ x( D* c    user-message (word "There are too many cars for the amount of "
  _; m+ A0 x2 e                       "road.  Either increase the amount of roads "
5 U1 H" K6 ~- U* ?                       "by increasing the GRID-SIZE-X or ", d. N( v* y& b3 O) X. t) [
                       "GRID-SIZE-Y sliders, or decrease the "& F/ O- J+ f; C/ ~' j0 J! p- E
                       "number of cars by lowering the NUMBER slider.\n"
3 |) x3 ~  G+ G3 R* u                       "The setup has stopped.")* v: t) o. J6 J3 Y+ m" p' n. w! O
    stop! h5 S, z  R2 d4 Q- o7 S! |  n3 t
  ]# Z$ {. ^: c+ [/ C
& L# m* u2 O" A4 x
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
0 \  u# q9 ]* e  crt num-cars
1 m0 X5 S- x1 ^5 t$ n, M2 |  [; F6 ^5 k/ M* i. @7 Q! E! R1 {
    setup-cars
, }2 }5 P$ j+ Z0 s    set-car-color
! ?) |/ Q# \- F9 e    record-data8 g+ a. ?4 ^8 G- Z. z- w
  ]. s. E9 b( I; p+ L- D7 T

1 c5 \0 i. Z+ g9 z* g- y* m! e& t  ;; give the turtles an initial speed
  l/ d: K' k/ V  ask turtles [ set-car-speed ]
0 C5 p; z8 s# E; ?  T+ n' L
  d' s0 K( ]. u9 t5 n; j1 c* K& d  reset-ticks, f) x* z+ U/ ~. C: J' ]1 n
end, L+ E( t2 ^+ N9 X1 d

+ a0 r  U3 h# ]# G8 ]. d: x;; Initialize the global variables to appropriate values
; X. y& B$ n0 t/ H' e  ^to setup-globals
# W: e( E4 ~5 X: T6 o5 S  set current-light nobody ;; just for now, since there are no lights yet
8 o4 L2 W  g6 ^/ e; E* k: ^  set phase 0  |1 j. T! ~. w9 c# K: H
  set num-cars-stopped 0
7 O2 P6 v) n& N, m( K  set grid-x-inc world-width / grid-size-x
9 R" V8 }: V# E! O  set grid-y-inc world-height / grid-size-y
; Z+ y) b4 c+ j3 N- _2 u9 J# L. B9 `' n: Q
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
8 P7 w( ?! c! ~/ i& d5 t: L  set acceleration 0.0997 D0 j: y4 g" r1 F0 y1 y' D0 J
end# L. f/ |6 ]+ L

8 p, J% g8 \2 i;; Make the patches have appropriate colors, set up the roads and intersections agentsets,) ^! }5 {5 {; P
;; and initialize the traffic lights to one setting" R8 ]; L! |/ ^; o- G8 h
to setup-patches8 c# V! O% N) u
  ;; initialize the patch-owned variables and color the patches to a base-color. y9 i* s  }2 s' H/ S
  ask patches
. ~1 }1 w# l* `4 s& u6 L- w  [
& ^3 ?4 \, d) {, c6 A* S6 c( ]    set intersection? false
! y/ K# Y# b! T7 m* W2 m    set auto? false) \7 \' X/ t! U2 }( z
    set green-light-up? true
" G& U8 \8 s1 ^/ v) A: ?- W    set my-row -1* q  i( H. v. M$ n" j
    set my-column -1, I6 s( ~! n$ O& Z
    set my-phase -13 g! m! F; _% |# R( e# D
    set pcolor brown + 3
3 L3 U9 X, f! z7 s  ]
1 j& z- t( Q5 t9 W$ {6 A- U8 A
' E0 {% H  N' j+ M& i/ Q. K  ;; initialize the global variables that hold patch agentsets
$ E! j3 ]* t0 ]3 Z# U3 _  set roads patches with$ v3 N+ J' e% Z; A% Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or; s5 T- v' z4 P& g4 h
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], }: P7 _5 r% t  Z8 w
  set intersections roads with
% C7 J- X- `0 e" W- ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and1 t8 k- z! K! L8 v" {, k. R( y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]; T) A: m) q7 `
/ ~$ y9 k' L6 G* S. r- M# L+ C
  ask roads [ set pcolor white ]( J1 O8 w. m6 G+ {$ Q' J: A$ {
    setup-intersections
% ?& t! ]: a, S8 C# Yend
, p2 l6 @7 {% I- \: A6 C其中定义道路的句子,如下所示,是什么意思啊?4 H3 l( O- G, h3 R
set roads patches with3 K  |+ }9 o, x, T' {2 t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
2 C; u" j' I, q8 X- R' ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
: L5 i9 B* M) i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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