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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。& F6 p5 |5 @  q$ M+ n% ]4 u0 [1 D
netlogo自带的social science--traffic grid这一例子当中,
% |1 [' ?& `4 S* G. tglobals1 U, n0 [9 e! o! k7 N- ?% G% s
[
3 c& A7 R: z, Q  grid-x-inc               ;; the amount of patches in between two roads in the x direction
6 s8 s" O, s: l5 E; H  grid-y-inc               ;; the amount of patches in between two roads in the y direction
% y5 T4 C" V- ^- H  acceleration             ;; the constant that controls how much a car speeds up or slows down by if0 f$ B. @' @2 T0 ^" `0 @0 R* m
                           ;; it is to accelerate or decelerate
% M) t! h( g0 T& G  {. V7 r- G  phase                    ;; keeps track of the phase
: E" E6 c4 W4 k. |  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
% g$ V3 J1 i/ i, \  current-light            ;; the currently selected light% Q, J; @% @/ A; t
) c$ g7 C0 l& a
  ;; patch agentsets
% A1 a2 x# `0 t0 U$ [' r/ H  intersections ;; agentset containing the patches that are intersections
# q& ]+ ^' s! w9 f1 k& R  roads         ;; agentset containing the patches that are roads7 }8 w& M% U. q
]/ @: b2 S3 Z1 E4 @: n6 t/ ^: I
" w2 ]7 [6 D& J& ?  i
turtles-own
7 c% m0 N( ^9 x[8 s$ M: H0 C  S* z1 S
  speed     ;; the speed of the turtle  e, B6 U1 J* g% G
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
7 p$ d. J, S- Q' @  wait-time ;; the amount of time since the last time a turtle has moved, Q. h7 a1 @2 T9 o. ]/ ?- B
]1 \/ k- Y4 L$ W" o/ o- ]9 W; J5 d2 r

6 W/ S4 M# j. v0 h. W1 U; M$ U. rpatches-own
" y2 D- M, o4 J$ |; Y/ j% A[: n2 A+ G- A9 G6 H; W6 Y- Y/ v
  intersection?   ;; true if the patch is at the intersection of two roads; L( q# y1 E/ t; A$ i1 ~7 v% o
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.. Q& k3 ^! L, T$ [- X2 ~6 r
                  ;; false for a non-intersection patches.
8 |* f. ?0 `4 W! F  my-row          ;; the row of the intersection counting from the upper left corner of the
$ J: x' A  k  @4 D                  ;; world.  -1 for non-intersection patches.4 r" z1 D6 X+ a
  my-column       ;; the column of the intersection counting from the upper left corner of the
7 d% }* }- }: l5 P( g                  ;; world.  -1 for non-intersection patches.
% O4 \$ z; C) _) I4 p  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
" g% G# f; X; g5 ?4 T$ S+ i  auto?           ;; whether or not this intersection will switch automatically.
, B& R- }! T2 J, R* R% J  J                  ;; false for non-intersection patches.& l2 b8 ?; f+ _
]" p6 t5 I- E3 E4 g  _7 J! A
( c! M* L) S' b7 V0 {

$ [. z, d8 ?3 n, h$ q;;;;;;;;;;;;;;;;;;;;;;
" ^' R4 e" p0 E% T& I7 I;; Setup Procedures ;;
. T" R. ^8 I( G- F! f- };;;;;;;;;;;;;;;;;;;;;;
' J. `! v: n/ l: G
. r  k2 ^: S! x, {;; Initialize the display by giving the global and patch variables initial values.
8 z3 ^8 q% O: u& ]+ m;; Create num-cars of turtles if there are enough road patches for one turtle to
9 {, n  a3 _4 w/ t6 K;; be created per road patch. Set up the plots.; l. }8 h! o5 q9 z9 X' [- u: t
to setup. `: J: b9 c7 _' K5 d  c
  ca6 B& q) K; B# |7 m
  setup-globals& X6 l9 c8 r& A
( G+ U1 n% ~3 E6 Y! ^$ e& y
  ;; First we ask the patches to draw themselves and set up a few variables6 x0 `( U( T9 i& b6 Y0 g3 x
  setup-patches
# `1 O& @  o( j/ f* a  make-current one-of intersections- g  G; F- B7 t0 \
  label-current
$ A' {8 @! V# L' M
' O- G# W6 g. e# t  set-default-shape turtles "car": v2 n' H$ ]7 O" \3 Q4 s6 U8 q
5 T: v  `$ [" A) H3 H
  if (num-cars > count roads)
9 A" _5 O* y6 [! W1 {/ e  [3 K1 t4 E/ ]9 o. c: g1 v8 v
    user-message (word "There are too many cars for the amount of "
: {! O% }/ H- j, m                       "road.  Either increase the amount of roads "
- i4 M( `3 T$ v% s% W2 e& _* s                       "by increasing the GRID-SIZE-X or "
+ O" y7 \% Y  e                       "GRID-SIZE-Y sliders, or decrease the "
  N& E2 |; n' ?" |2 j$ {( m* i                       "number of cars by lowering the NUMBER slider.\n"
0 i+ m' P, e% l: v                       "The setup has stopped.")
; ^+ P* u- Y. q4 n1 o2 a6 I    stop
8 b5 \, v8 G6 j, g  ]! o) Z. Y( J3 J
0 v" s. y* a7 y' X+ q, d
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color! L  c# ^# r; P7 i
  crt num-cars
. ^2 H7 b! L4 f: R) E7 l* ]6 M  [
* @4 n+ \# i( T. W    setup-cars
6 X5 G0 o4 A) [. S% X    set-car-color
4 D( D  ~9 _1 R, @4 b& [5 J    record-data
9 i; L2 i/ R2 f# x6 C4 y$ B0 k  ]
. C- p  k+ \* f; W2 Y) q) z( w; k( l
  ;; give the turtles an initial speed+ M) p( W0 u) G. I/ z0 h9 E
  ask turtles [ set-car-speed ]
( H! H$ l, f7 k. U$ Y: w4 A% J- \" M% B  F" j4 p' {
  reset-ticks
* v9 k# ?2 b% n& @+ v6 `8 t" \+ D. Fend  B/ d& K: U; l4 \2 Y6 n5 ^, w
) t/ V6 ~( @: o  W4 N" f- T) y; q
;; Initialize the global variables to appropriate values( p+ _  d) [4 A! n. J4 c
to setup-globals" D) O* ^9 _& M* L/ k- W
  set current-light nobody ;; just for now, since there are no lights yet
9 D5 ?9 g+ ^+ l3 ~( \" F* ?  set phase 0
/ }+ U0 `! j4 r4 H$ D4 O5 P" _  set num-cars-stopped 0% O; @. H3 e. O
  set grid-x-inc world-width / grid-size-x
! A8 }6 B# \, L: x  set grid-y-inc world-height / grid-size-y" x$ ~. f: X, v3 v1 F8 ?
' ~6 _# w1 t. X( s& w
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary# o- ^- O( q& I% ?* }
  set acceleration 0.099: D* w( m8 r& N! x! f
end% i9 X( x" W" U- w1 s. Z

: ^% R& @: j  O+ s' n+ _- V: j;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
) h2 ~3 a0 `7 y7 d4 Q;; and initialize the traffic lights to one setting# u( \- |+ r$ x
to setup-patches
' {2 {( _7 x- f6 P9 w2 ^  ;; initialize the patch-owned variables and color the patches to a base-color
9 y/ u, [4 V$ w$ B% U  ask patches
4 a( u; i9 {* S; _7 l6 b4 I0 N3 e- {  [/ ~1 H  N; i* {: `' N
    set intersection? false2 n. m" y% s% o/ e: C
    set auto? false( Q3 C: g. @- \0 q, O/ t# X8 J; l
    set green-light-up? true' L. G. Z) \5 b0 i/ b
    set my-row -1
* I. \) Y/ E/ f; E' `    set my-column -14 W# Z7 V+ f; Q$ M
    set my-phase -1; l4 l0 ^1 G& w5 r7 @
    set pcolor brown + 3
# r3 [$ S. l+ @/ A) p% b  ]  b- O+ e5 L. R) g% ?* w

1 E% L3 o- S) ]" [  ;; initialize the global variables that hold patch agentsets& ]# V$ }, b8 n9 ~' s6 v& U( i2 C
  set roads patches with
% Y5 Y5 F# }) q9 ?1 S. U6 d    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or$ y4 k* G, K8 A! ~( h4 @
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 u; ^  s& O1 g- O% s  set intersections roads with
$ q# f: H0 R1 [! a; u+ ]' z. c5 L    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 i$ C  ?; l) ]9 E: q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
7 ?* h5 \) |" {) _" v3 N/ D; h" U% F1 d9 a, h, D
  ask roads [ set pcolor white ]  m2 k; b. h- C) s
    setup-intersections# \6 f: \2 W: z0 R% L9 \
end
0 [, Z3 N  V; u  B其中定义道路的句子,如下所示,是什么意思啊?
# C7 w3 l3 T) F/ G set roads patches with) d( U/ j9 J  P4 D+ W  t* t
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or+ U  J/ S! ^4 q* B
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
1 o7 _4 X" O7 i% I! 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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