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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。! s. [4 @8 B4 ^  a, Q7 N
netlogo自带的social science--traffic grid这一例子当中,
3 }2 Q  L8 x$ i( |3 k; G0 V& bglobals
/ p$ O! n: U9 X" K. z; @: }6 y% y[. M" ~3 _+ R1 o2 }
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
4 }. k2 R& N9 ^, X$ x4 t7 q  grid-y-inc               ;; the amount of patches in between two roads in the y direction
: \- {* f0 q/ H0 o5 o  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
  u, Z9 b" F: c" n1 @                           ;; it is to accelerate or decelerate
9 G4 z1 v4 M7 _# T: i: J& x  phase                    ;; keeps track of the phase) v" K! L' {+ T0 b
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. r8 P" }9 B  K. |- k  current-light            ;; the currently selected light8 o) ]8 c) q5 i/ D

) }) |. H5 ~* Q9 u  ;; patch agentsets2 z/ O* I- W( H( Z
  intersections ;; agentset containing the patches that are intersections
5 h1 D, r- |7 z8 h  roads         ;; agentset containing the patches that are roads, i6 M8 g# _  T2 H9 E
]
% f3 C+ F% b. y$ W) Y& q1 s% r* F7 _3 O9 ?* |5 w+ y
turtles-own* b6 o  m5 |  w+ H1 E) o
[6 K) g+ w# R* E- e4 K! A
  speed     ;; the speed of the turtle
6 F. M  D3 x8 @0 i( u  N* {  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
2 o' |8 f: B, }8 q: Y: C$ k  wait-time ;; the amount of time since the last time a turtle has moved
# t4 c/ D& [2 W) n]
( I/ e1 `) A' W: Y* h' {3 v! l7 q( L( U  ^& U5 t
patches-own
- g7 P; h$ L8 F9 f[. M7 u' {' s) h! O+ A, |* e
  intersection?   ;; true if the patch is at the intersection of two roads
4 S& X: M- g) `# }1 |7 _  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.( e! F6 a" y; e5 ?/ ~- {" q
                  ;; false for a non-intersection patches.
; B) s  S: \2 T$ g  my-row          ;; the row of the intersection counting from the upper left corner of the& {+ B% M" i; `& g
                  ;; world.  -1 for non-intersection patches.
0 J/ v1 h  k9 r5 F  my-column       ;; the column of the intersection counting from the upper left corner of the
6 ~) S6 p& N# |9 V, e7 f, l2 E                  ;; world.  -1 for non-intersection patches.
! ~$ }+ `$ a$ `6 Q  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches." @# k7 z0 u. T7 C( ~) t
  auto?           ;; whether or not this intersection will switch automatically.
$ e, |  n' k) }5 i& N& v                  ;; false for non-intersection patches.
$ ~0 Y7 b6 V; I' @# G% @4 Y7 o]1 x% G! `3 \: i
" ~9 Q! U/ I7 |' Q( @! h8 I6 g+ g! q

8 i* K/ n# p3 o' {3 I" M) S) N;;;;;;;;;;;;;;;;;;;;;;
4 w  N3 I4 L' I6 ]+ D* B;; Setup Procedures ;;
2 G6 P+ w1 M3 h- s2 ~. M) u' I;;;;;;;;;;;;;;;;;;;;;;. F' T4 ~# {  ~1 y

9 _# o1 X+ Y# \3 A, a;; Initialize the display by giving the global and patch variables initial values.
$ ?7 \! q& f" C;; Create num-cars of turtles if there are enough road patches for one turtle to! a$ |% A8 ~' n1 v" [+ h- [
;; be created per road patch. Set up the plots./ D# Q- t2 j3 m& q' s/ F
to setup
7 k5 p0 U# N. h" h2 q  ca
8 V' B$ ]& M% e% m) H- E) i  setup-globals! ^: G7 c; o1 O# ?9 k

# N6 p$ O: D1 a# ?  s  ;; First we ask the patches to draw themselves and set up a few variables+ _, T* |, q$ H4 v& J( k* R
  setup-patches, S  Y' @( @0 Y0 f" j3 g& k/ J
  make-current one-of intersections9 x  w. s. @/ R4 H& \& J; q% N# V
  label-current
; ?$ Q# }5 O- V0 @+ H) b
) ~- j* J8 \+ x  set-default-shape turtles "car"# |9 A& t& c* T, ^
- Q8 a2 g: f# I# ]
  if (num-cars > count roads)) J; [# e9 @& x$ {: e3 L) V) ~
  [9 J6 ~5 z  C) H% M6 I+ _
    user-message (word "There are too many cars for the amount of ". D( B( ^: X! `( U+ m; x
                       "road.  Either increase the amount of roads "
1 a( o) i( k# K3 h- M                       "by increasing the GRID-SIZE-X or "! ^5 x+ c: `1 a' U- V0 z
                       "GRID-SIZE-Y sliders, or decrease the "# @/ M6 a1 ^% r" s
                       "number of cars by lowering the NUMBER slider.\n"
7 g5 u/ X+ J; p- n  C                       "The setup has stopped.")
# e/ Q4 \6 @& l6 S" H' a    stop& T1 P7 _1 m9 w  l8 j: B; I
  ]
  x' z4 f! _" q; v# h% B' R7 ]" I3 Y8 j. P) C& E
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color2 u* ?8 M) O  [$ T
  crt num-cars2 j2 _" D! o5 v9 q8 P" D
  [9 O5 j' E1 w$ n) |6 x( a) A
    setup-cars
  H* K: V. N$ J) \    set-car-color# Z+ p* t' \6 _  |- ^
    record-data
" S, g- I% x: @6 A; O2 D  ]
; n! Q1 X: L2 K! S
; G" o  c- U7 M$ W  ;; give the turtles an initial speed
" e0 {( _) b( x4 q( E' h! R  ask turtles [ set-car-speed ]
5 n: f$ ^7 n6 H8 S: x
  |/ Z6 n/ v0 p; H4 i( P  reset-ticks
  O$ R, L4 a7 q) ?8 Send1 o, y& r% ~" O' o. O  A, S3 G. \
4 W. ?; v9 a8 p3 n' J
;; Initialize the global variables to appropriate values9 E9 L3 o8 s% O; y) x
to setup-globals2 x( I# `0 s9 v: b0 z
  set current-light nobody ;; just for now, since there are no lights yet
- ]5 i$ v& V3 t* h! I9 i  O  set phase 04 ^: ~. Y$ T: d/ G4 {
  set num-cars-stopped 07 h6 y  R- E- u/ M
  set grid-x-inc world-width / grid-size-x# K" K. g& `- y/ F/ D+ w& H. \! b
  set grid-y-inc world-height / grid-size-y
4 ]9 u7 @  ?6 F* ]! h
, K0 E4 t! [6 G3 G5 C! c% G  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary% G! a7 p- N. o- R/ W) p+ X' E
  set acceleration 0.099* B/ [) t4 }* s
end/ G( P7 ^) G/ k$ E* K! }  @

! I; G% l9 ?5 F* O& ^, a;; Make the patches have appropriate colors, set up the roads and intersections agentsets,$ u& K4 R  N5 ?4 G4 B% j5 D& m
;; and initialize the traffic lights to one setting9 q; k: \, ]. J; c" w6 p3 t
to setup-patches
6 A1 N  v. g5 M/ r  ;; initialize the patch-owned variables and color the patches to a base-color
, K9 C; Z1 k& E' k2 c: i8 l( C  ask patches
( q$ J4 t2 i( V  [) O+ A- r8 r- g/ H7 _$ B
    set intersection? false$ x0 E' z# {! ~, p8 N
    set auto? false0 s* d# H6 _! P3 M
    set green-light-up? true
  \' k7 D& Z1 K& k* q, f. V    set my-row -1) b7 A9 p2 D* C5 J# s0 D' g
    set my-column -1
- \9 Z: H5 |  h( u: k    set my-phase -13 j3 i  E' y; N5 ~$ w4 R6 Y' `
    set pcolor brown + 3
1 Y  i4 _1 ?" F, f& M9 Q+ G) [  ]
* f. f1 {, N, Y; I+ F2 ]! l/ @+ E4 @/ q. I% E
  ;; initialize the global variables that hold patch agentsets
3 i( ?, Y2 R' {5 {+ o9 T: y/ s  set roads patches with; y' y3 G1 c$ @2 K6 R' c
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 e5 J! [$ Z  Z, S
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; }  v7 M5 c8 n  |. o1 i5 `5 [  set intersections roads with8 d% \- n. D# Q( _
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and5 f1 j' S) A" e0 }7 ^1 L3 K
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]" K' ]0 y8 ?0 y. m6 D
7 M* s: G  B+ e1 z" [: @. Z! {: X
  ask roads [ set pcolor white ]
4 J0 s( \; m6 m( _    setup-intersections: h0 e9 Y# p! |8 m7 j, ^
end
+ R' D5 C+ e: z' W其中定义道路的句子,如下所示,是什么意思啊?
, R2 ^. \" W) W  G4 U, v" V set roads patches with
& v% n2 T* t/ ?8 H    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
" u- U6 R' w6 j( [    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]2 F/ g# f# |2 p- ~
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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