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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。5 L/ a- s3 u/ G8 f0 N+ _. O
netlogo自带的social science--traffic grid这一例子当中,
  A) h( x: _7 S( U) Mglobals
; U$ ?+ U$ e) A0 H. j; }5 M[+ O  b* x2 x7 ]5 `1 Y
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
! `( C! `/ t$ S* Y. X" y* `  n: n  grid-y-inc               ;; the amount of patches in between two roads in the y direction
4 q! ?% `3 Z5 X8 S  acceleration             ;; the constant that controls how much a car speeds up or slows down by if9 b( V% W+ w# u% J: n: Z
                           ;; it is to accelerate or decelerate$ M. D' e5 ]  q$ e
  phase                    ;; keeps track of the phase! M' Y8 G" J* H% `( Q6 A" o/ H
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
0 J1 }% _; _( h' {  G2 f& c9 n  current-light            ;; the currently selected light; Q* l# r1 V8 Y0 X$ o
3 i1 e; D+ c! C) K. c
  ;; patch agentsets
8 [/ O0 F- k/ Y% d3 H  intersections ;; agentset containing the patches that are intersections  R( D  @# [; A' c' q
  roads         ;; agentset containing the patches that are roads
; ]$ |, H" s, h1 Y9 f# K]4 t* O4 g9 s4 ~; G8 ]
, `; Q! ~5 e+ T. O/ j1 o
turtles-own  v  j1 Z- t/ z
[4 [+ ?( l9 Z' V# {/ _
  speed     ;; the speed of the turtle! Z1 T! E& V( D* _6 S7 d% c% v# b  U
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right( S7 A9 e* s! {" n! I3 K# \
  wait-time ;; the amount of time since the last time a turtle has moved- B* A4 i- v0 T* K, P& h. J
]
' F7 @: O2 w$ T' \. ~, \, \4 r: }" u3 k  ]1 s0 z7 k# [: E3 {
patches-own
& @$ ^3 T/ _5 k& h: X& N- l[
5 \( J) f2 g4 ^& q  intersection?   ;; true if the patch is at the intersection of two roads
# K( M" t4 ^- H# r: r2 \  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 p4 H# ]+ ^) x, }( ^0 s                  ;; false for a non-intersection patches.
% t, x5 U! r0 h& n9 g" ~; Q; n( [  my-row          ;; the row of the intersection counting from the upper left corner of the
, N$ u) ?$ q* e3 X# l6 z% i, O: z                  ;; world.  -1 for non-intersection patches.% S) `5 i* p' g# y
  my-column       ;; the column of the intersection counting from the upper left corner of the
: |2 r' x7 w9 i" {  \                  ;; world.  -1 for non-intersection patches.
/ M; y8 A9 Z6 X; ^  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 s9 `: J" i% D: q/ ?  auto?           ;; whether or not this intersection will switch automatically.% P1 W; W, H2 m7 o3 [' ^4 w
                  ;; false for non-intersection patches.
- P% o2 q( @" V/ F" I: {3 m/ u  K]
: M( g- j! n) ~. T6 y5 M9 \& L. B7 K* A4 z! W
* w/ o% m% D/ \* K5 |  b
;;;;;;;;;;;;;;;;;;;;;;
' A! J# D9 w: Y' K;; Setup Procedures ;;: v1 V; ?; T' d4 g& W( j
;;;;;;;;;;;;;;;;;;;;;;
+ l* B! T: B& P* K
( ]7 n0 R- k! A6 b0 J" Q: W6 r;; Initialize the display by giving the global and patch variables initial values.
& Y7 F  q: l8 G0 h( G) L;; Create num-cars of turtles if there are enough road patches for one turtle to2 G* J' N9 h* ?4 I* `9 F; z" w
;; be created per road patch. Set up the plots.! S7 Q! Y4 A- ?) J& B
to setup
, ^8 z; e0 F  D% X3 \* C  ca7 k9 J$ C5 d6 ^2 w2 i3 u
  setup-globals
$ X$ h* k! j7 _# `; w. L" D1 b
( T. I% A# e( k  u! R5 W% t  ;; First we ask the patches to draw themselves and set up a few variables
6 y4 u* f8 D, q. ?% ?  setup-patches
1 c* e. l0 m& x9 @' ^  make-current one-of intersections
1 s. T6 ]5 A9 X# W. p7 E: {; R& Q  label-current. q4 `1 k9 m9 H8 b

+ y0 Y" g+ T9 R  set-default-shape turtles "car"
( p" u: ?0 S+ A7 s) [  g1 Z
$ j4 N, u& D) J0 r- r  if (num-cars > count roads)
7 Q+ }2 G# V; F. E3 Z4 T9 h2 `  [4 J. T5 Q  E" K
    user-message (word "There are too many cars for the amount of "4 V5 u! Y+ x0 q4 O  G" q* q, U4 m
                       "road.  Either increase the amount of roads "1 y* b$ Y$ x  C* a
                       "by increasing the GRID-SIZE-X or "' x" e5 h) h' c: u2 i1 r+ f
                       "GRID-SIZE-Y sliders, or decrease the "
" N- D. ^! d  B5 E/ @9 u: L3 X                       "number of cars by lowering the NUMBER slider.\n"6 h2 ]9 q/ w. \2 o$ P  [3 T
                       "The setup has stopped.")( ~% M0 d4 ~) e  I) l3 q0 \
    stop7 n0 q. A# e# M9 o
  ]
, w/ A% S! {$ @7 s  ~( ]9 u# j# B, J! L1 ]' g9 k
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
; G& K7 t, k# `, P6 P2 Z/ q2 H9 Y  crt num-cars) {  n' _8 L3 {: b, h. P$ ^
  [
1 v  h: Y3 E3 D, `& X  i( D    setup-cars9 c; s1 O. O, E8 ?
    set-car-color
5 T; @! A+ j) G! a" M    record-data" ]2 d( f" ?8 L4 T- i7 E1 X
  ]
2 H% U; O/ C6 K+ Y
( w* |( h3 j' I6 g/ C6 r  ;; give the turtles an initial speed
0 ^* z! O& l' g  ask turtles [ set-car-speed ]: X5 y5 F. Z& }+ c9 x; d+ y

5 z: i. E) B8 _5 X  reset-ticks# o9 S; h+ p9 G' R
end2 L0 w3 d: P' W9 I( \5 [
) O$ Q9 Y0 |- d
;; Initialize the global variables to appropriate values
+ w9 s/ Q7 j" v% M1 y5 b% {to setup-globals
. x4 f0 a, @# E' }% v/ V  set current-light nobody ;; just for now, since there are no lights yet( X" X+ l5 R% [
  set phase 0% E: l4 J" a3 w  t4 V# f; b3 }
  set num-cars-stopped 0
5 \% a" V3 c, x( H8 [4 x  ]- O  set grid-x-inc world-width / grid-size-x
# P! \) z; {0 j$ I- t! `+ u" R  set grid-y-inc world-height / grid-size-y
/ h  r$ A  x& S7 B/ C  B+ T" G7 h5 c
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
. a+ [/ m5 n2 O  set acceleration 0.099. m% Z7 v" D; t2 w3 u. j8 U  T' ^
end/ L# o: \8 c* v9 `7 f% ]

! Y; M+ C* o! ]) X' h;; Make the patches have appropriate colors, set up the roads and intersections agentsets,1 W' `3 o1 b$ T1 K7 U
;; and initialize the traffic lights to one setting
! m' g3 l$ l8 q0 O" x% dto setup-patches
9 w! H" {4 }1 y) O" A* r  ;; initialize the patch-owned variables and color the patches to a base-color/ b9 B1 F% o7 B; A3 ?. c# `
  ask patches1 x" |. G/ }% \: h
  [
9 |& S# W3 o$ A9 @    set intersection? false& F2 P, K* P8 I" R0 K8 t8 c( f
    set auto? false* y% p8 b) b" `7 R
    set green-light-up? true
' G1 X7 r5 c! C3 l" q* ]    set my-row -1+ l" U/ n" T3 R/ Y6 ~
    set my-column -1
6 O7 b9 y/ o/ G2 E$ w  P    set my-phase -19 q8 S9 M- Z( {- v" p' ?
    set pcolor brown + 3
1 Z7 \1 A- [" h" Z1 Q' m  ]/ v- l% v; g" T# W9 h
1 g8 G/ ]( i4 o7 E/ I4 S
  ;; initialize the global variables that hold patch agentsets
" j! z$ O3 _* [  set roads patches with
: E$ [" s+ c0 b* u6 n7 m8 A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
5 w) W. ^# {2 g3 k    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) W" n% w; K( C, K6 j  set intersections roads with
3 r$ u9 Y& r- R0 x) N: k1 ]    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and6 f1 M3 H/ U0 {1 ]$ F
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]( P: Q1 q3 ^* ]  ]2 {
/ P; K1 T* C9 v
  ask roads [ set pcolor white ]
6 C( e' j) F; D  K# M, v% i2 d" a- h$ V    setup-intersections
* y6 a, t! d5 n2 N- q  ?end* I0 X) g7 P# s  I/ ]' ?
其中定义道路的句子,如下所示,是什么意思啊?
8 P% u5 y5 m# D( A! @7 X, x! Q# ` set roads patches with, @8 |, R3 ?) O! ~' \" z  m
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: `3 [: H. w7 ]    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
  T- ]+ @# }) X5 u, [; j: t) T5 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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