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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 l7 K$ h& N2 C+ x( K  J( bnetlogo自带的social science--traffic grid这一例子当中,6 A0 |  t" w% f# U7 e, D% M
globals
" }/ J# C1 A: a' j: I' G[: s% `; z( p5 w% ~/ [
  grid-x-inc               ;; the amount of patches in between two roads in the x direction( U6 U/ Z3 |8 q) @7 Q! n8 c4 W
  grid-y-inc               ;; the amount of patches in between two roads in the y direction$ ]% q  |3 m" N
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
& _: x6 F+ x( S5 \& @                           ;; it is to accelerate or decelerate
0 o* ~* t' W) ?. m6 T9 _/ I2 K, X0 \  phase                    ;; keeps track of the phase9 [( @" v2 q4 w. j* ~3 F! z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure/ g: Q2 u8 s5 f* q
  current-light            ;; the currently selected light
  H, l( g+ H! ]
& N( b" a( V. u- h2 o4 \& Y  ;; patch agentsets. Y) x; Q3 Y; k% R
  intersections ;; agentset containing the patches that are intersections
6 g& X, j# B' j1 \. I5 {  roads         ;; agentset containing the patches that are roads
! _: ]  E% i+ x; z+ ]]
$ u! |% E  U' O5 D( k# _1 _+ I4 l! D2 C
turtles-own5 T6 j( ~) |  ~" @% Y0 |
[2 W% o# H8 E3 b3 U* e) E
  speed     ;; the speed of the turtle4 W0 W+ q; z" ^  Y0 n
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
/ L" D4 C0 F4 d* r5 g: @  wait-time ;; the amount of time since the last time a turtle has moved
1 u! v- E$ m& e- _  ^1 P9 p]2 E$ B9 ?9 k+ J# _6 F
1 e. |' z: U9 O" u) v7 n; t. q" ~
patches-own+ w4 o; W; T- J2 X
[
) ~: `$ m1 |+ g, h; c9 d( B  intersection?   ;; true if the patch is at the intersection of two roads
4 w; q& y7 z8 k7 C$ V) K& M9 n" \/ w  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
8 M9 W$ n0 P! a& W# p, }) H                  ;; false for a non-intersection patches.; }. j. B6 A5 L( x' w, w
  my-row          ;; the row of the intersection counting from the upper left corner of the1 L2 t* c0 _; f8 U1 l, \$ |
                  ;; world.  -1 for non-intersection patches.$ V% Z$ C* V" R" E' v% t( @
  my-column       ;; the column of the intersection counting from the upper left corner of the
  N" N# m. k/ v! t& k; ~9 ~                  ;; world.  -1 for non-intersection patches.
" y& _1 w* e7 Z. j1 h  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.) w, [2 k9 F6 W% g' j
  auto?           ;; whether or not this intersection will switch automatically.5 E9 x3 X. a+ a; b2 E
                  ;; false for non-intersection patches.' e" S. z9 G* |% G5 V
]
5 s0 Y8 K% X: Q4 z/ I. S( s. i0 q0 `' V5 J- I. k7 v  S

! J$ u2 _" l8 u& B6 D2 n$ J;;;;;;;;;;;;;;;;;;;;;;
( U2 K+ P* }) i1 c* f;; Setup Procedures ;;: j, m$ r% I# E, k/ K1 f
;;;;;;;;;;;;;;;;;;;;;;' \( H  v* R0 `

* L/ z% C; ]1 j6 D4 [2 K;; Initialize the display by giving the global and patch variables initial values.8 w% i9 o, \* n% ?3 k' V& b
;; Create num-cars of turtles if there are enough road patches for one turtle to
3 h9 i2 k& P  k* Q. s3 ^0 Q( E;; be created per road patch. Set up the plots.8 Z, x; h3 A& J0 [1 J; e1 w8 L
to setup+ m- O  J8 o0 l6 x1 K/ {
  ca. z' _6 ~( T/ r" T. F, C
  setup-globals) l0 v2 Q+ U! A% E! i" K

$ W! S/ }# o. F9 D! I6 y4 `& c3 [1 P: |3 z  ;; First we ask the patches to draw themselves and set up a few variables. l5 H2 j/ r: F! D* t1 Q
  setup-patches+ g# ?# H0 S, H- Q0 p0 o, ?* N
  make-current one-of intersections/ T9 j8 G. m" J* R" ~. Z
  label-current
% M5 Q% H* z/ x3 |+ H
1 I0 ]: H2 f) I& X6 t  set-default-shape turtles "car") i  Q7 S. `5 I  e$ P0 I
1 N5 E- Q5 j+ m3 W8 j
  if (num-cars > count roads)/ ~7 X- W# p" A* z3 ?% w! Z
  [
3 \/ v* L9 b9 n1 i    user-message (word "There are too many cars for the amount of "
) O3 M2 a  O7 h, ^3 w7 i- j" x0 Q                       "road.  Either increase the amount of roads "
3 W9 |* k+ Q, n# {  v1 ~* u                       "by increasing the GRID-SIZE-X or "1 u: _9 R' ~  }! p9 e) |
                       "GRID-SIZE-Y sliders, or decrease the "  \8 P& y# m  |- Z3 }6 ]+ U
                       "number of cars by lowering the NUMBER slider.\n"
1 v: k: @, L1 z) `                       "The setup has stopped.")
+ u0 D6 g& h/ A  v2 S    stop
, d8 i; r* L/ O  @/ k/ K# [  ]
: ?6 h- k1 X- @( c" l$ r) n; t3 x3 t7 y  g8 u  i5 |' E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
8 h$ c7 o+ L% y  crt num-cars
1 Q) n" Q& z7 F& a  _( `. W3 p  [
! N9 O7 p6 k' n; j3 i$ k5 a1 Z    setup-cars
: N. y' D' {4 D9 t/ @    set-car-color
0 N- N! f, A- v) M5 L    record-data
# {8 c5 z  s6 v) }2 _# E  ]2 x* c# {3 r# I: k. l# K( B

( h6 d. e4 t3 {1 {, ]  ;; give the turtles an initial speed
6 s' p+ I) V6 ~: _/ u  ask turtles [ set-car-speed ]
. |; C/ J' t" J! q5 u
' o1 V8 x: a5 C( C* [  reset-ticks
7 U6 b9 R: p; f, G% fend
. _5 b# }% q. P7 P2 J& M* W: T; M6 i  l! _: R5 t
;; Initialize the global variables to appropriate values
* v9 C! w7 g4 b" ]- D& oto setup-globals
; ~' R; B" v' A  V4 a  set current-light nobody ;; just for now, since there are no lights yet. P; p/ e  v) l4 Q" p  _+ N
  set phase 0  y  a, F: C1 F3 K
  set num-cars-stopped 0
9 V6 ?4 X4 Z) ?, b# q- i" T# A  set grid-x-inc world-width / grid-size-x
& X% {& n3 ~3 C$ Q  set grid-y-inc world-height / grid-size-y
, `/ m* P* a% \2 h
6 g  f. ]$ [% p2 ~  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
5 V4 C* F8 O5 |7 e4 k. [+ @  set acceleration 0.099
: p$ |8 N$ }0 T, b! M3 _4 Bend
; ?2 `/ i# i; E) k& c, Q/ L  W% z  j$ j' B) p$ h
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- j% ?: n4 e3 T! w/ p3 w
;; and initialize the traffic lights to one setting* Q8 [# u$ x0 F
to setup-patches8 w% z7 m+ {* \+ D; {
  ;; initialize the patch-owned variables and color the patches to a base-color
5 ~6 c; r& C, H: _0 S' A6 l6 ~0 H3 ~  ask patches
4 \0 T  B4 s: g/ C1 m  [
6 K1 @# v" e; C( a9 e3 A$ t    set intersection? false5 P. U1 w1 O0 k" x- o
    set auto? false' {( a" S8 }# B. f1 Q1 q
    set green-light-up? true
3 y) A" z. L" I8 n    set my-row -13 }7 f4 Q( l6 H; w1 V( N
    set my-column -1
5 ?7 V+ n. N/ B3 T  A' k    set my-phase -1* ~* a3 Y2 K! S0 n) g- V# F: \
    set pcolor brown + 3* r, @% R% X) F4 C, Y4 q2 E' _& W/ }
  ]
4 V% A2 Z4 V4 L, a- g7 d) |6 g
: n% k+ t' S6 p  ;; initialize the global variables that hold patch agentsets* @* u! X9 o& O( ]2 u8 H) b- F
  set roads patches with
# a% R% C; C2 N) |3 p/ V0 A    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 f$ ?: E# M0 A- d. a
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 Z0 M4 j/ q" \$ N/ n, L" {" F) L  set intersections roads with
& r7 i" `8 H" t; C' D. b- ^    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
+ p* |- I- R& X) r3 s- R  K3 o    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 f, I6 B" ^% ]

# ~1 C$ x& \$ y  ask roads [ set pcolor white ]9 D" d7 e! E' L- f* a
    setup-intersections
& w! e8 Y! f- V  Rend0 R1 r: U- V! z& ?
其中定义道路的句子,如下所示,是什么意思啊?' b$ s3 D; J, B6 C/ T
set roads patches with% u$ I* P  @5 e' I! G
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or) B  ]( }* _( i# O. y9 C1 w
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 ], {! h5 K$ G3 \* A' {6 W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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