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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。
: |( D7 w$ d2 A; t: W- F0 u, xnetlogo自带的social science--traffic grid这一例子当中,
( K; W4 g1 s# F* n* u9 xglobals' E, i; D: @9 t0 ^5 G7 H
[
3 P# [7 U! M5 ~* ^7 c  grid-x-inc               ;; the amount of patches in between two roads in the x direction9 N: L4 d# K. X' P8 R8 {
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, a1 h( T7 _! |! ~) m) D8 x  acceleration             ;; the constant that controls how much a car speeds up or slows down by if+ X% a& L  k1 t+ z
                           ;; it is to accelerate or decelerate& z" }( a& U5 y, \7 T8 j/ }
  phase                    ;; keeps track of the phase7 B- W! ~( e7 O% f% P
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
' E4 h+ W' P: A  current-light            ;; the currently selected light( @3 R4 W# Z3 z& ^  R% X

' [! w: A% N8 h  ;; patch agentsets
7 i9 A' D$ T% }) D+ h' _  intersections ;; agentset containing the patches that are intersections
& s: ^9 P* i5 R; y* Q; N. \, U; [, i1 ?  roads         ;; agentset containing the patches that are roads
/ b8 R7 H5 T4 I8 o, \) O) ~5 O8 F]
5 ^0 X" l0 e) O: F4 j- |7 ?2 [& s# h1 `/ L% H6 U3 d5 y$ @
turtles-own5 K8 V6 }: C6 K1 Y
[
  E  Z5 s5 s8 r+ M4 w  speed     ;; the speed of the turtle- s: C2 F6 P6 N2 `0 t
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
, Q: g" z& q9 [0 Z/ p+ g- A  wait-time ;; the amount of time since the last time a turtle has moved7 J( G6 }7 u+ G' y
]
; ?9 X1 E$ s) V! g
8 q+ V% B* u* f) |' B- s- fpatches-own
4 Z3 d6 s( Q4 v0 |  |0 M[- z# O; k$ E3 {7 V6 O  t
  intersection?   ;; true if the patch is at the intersection of two roads& D2 d6 V% N( G  ?* f
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
* F! N, w  L8 x1 n8 U7 X                  ;; false for a non-intersection patches.9 s- t0 t3 U4 }
  my-row          ;; the row of the intersection counting from the upper left corner of the
9 L& K2 [) {) ~% _, D                  ;; world.  -1 for non-intersection patches.' T# }3 a+ ?  C6 G: F! U! H
  my-column       ;; the column of the intersection counting from the upper left corner of the
8 a% d" n' M; s                  ;; world.  -1 for non-intersection patches.: u$ r1 J5 r0 i( t
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
; J$ Z& b- y( q% t1 Y8 H9 |  auto?           ;; whether or not this intersection will switch automatically.$ w2 i7 w# n' ?$ E1 W3 o
                  ;; false for non-intersection patches.
) F; |0 O1 l0 Q3 \5 K]# S& a0 Q4 p6 [: t; |
; m! a' r+ J$ z# M- @
& C- j8 N+ ~1 w# g) J" Z7 k9 [' \
;;;;;;;;;;;;;;;;;;;;;;, }% }- T5 q. x9 Z* Y
;; Setup Procedures ;;2 e# N4 k' S7 T  w. G; y- V
;;;;;;;;;;;;;;;;;;;;;;
% ]( |/ l8 y' a6 g( C, K
$ ?/ d; Y$ I" ~& o. [7 Z/ _2 l;; Initialize the display by giving the global and patch variables initial values.# \9 O$ j- v3 O, L: T! u
;; Create num-cars of turtles if there are enough road patches for one turtle to
% K: u# E( C) p" r0 y;; be created per road patch. Set up the plots.
7 W" _5 ^) u$ g" j, [to setup
$ h; V7 r, ^$ A1 I  ca: g7 G7 _8 W4 S# R* \1 ]+ ~) a
  setup-globals: B, f0 V& ^1 G, U

' t) a2 ^6 T$ v' ^! \6 T) O  ;; First we ask the patches to draw themselves and set up a few variables, g- L( m, I4 r' M7 T( S* d$ _6 ?2 ], S* f
  setup-patches
/ f+ t" J% q% v: M5 _  make-current one-of intersections
. r: i$ @2 F3 g7 @  ~  label-current
3 i9 Q! v# R* j6 I" E4 z; A! K* |$ p. q8 P* s1 M/ z5 x) w
  set-default-shape turtles "car"
( E  P' F1 q& o% [/ ]1 W& w
" Q0 g2 {+ t. p  if (num-cars > count roads)
: r8 b/ f/ T8 y2 b# Y$ [  [$ x. }  }2 `. c8 U% \
    user-message (word "There are too many cars for the amount of "$ b( t- c' Q: _7 g+ D% l: j/ Q
                       "road.  Either increase the amount of roads "
. S( R/ Y1 Y4 E, f7 }+ O! ?                       "by increasing the GRID-SIZE-X or "9 e: Z) c4 }" t% E3 j
                       "GRID-SIZE-Y sliders, or decrease the "* q, D, f  F1 {  \! n; p' |
                       "number of cars by lowering the NUMBER slider.\n"
7 o8 V9 E  a* x3 @, w6 }6 q                       "The setup has stopped.")
. j, `5 D6 E( v$ ]    stop( t( g$ T( @3 z1 o; u' s" P
  ]
: n7 U  K' o2 q: p( @0 j- e2 h9 [3 }; s1 R
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color1 S7 F" M4 ?8 W* y, G1 }# W: {6 m
  crt num-cars4 F, Z( r- O& n. J2 e- V9 b
  [; W3 z% X% g  V) `5 y0 I% a. ]
    setup-cars
  h: }8 ~* _0 J8 k    set-car-color' C! k+ A6 j* p% p5 Z" \; b
    record-data
5 ^5 ]% ^) H# E2 B/ l0 `  ]
2 r$ x6 F; N$ R6 _, {: z2 p+ N* O( d: l
  ;; give the turtles an initial speed
! ~8 c* ~4 m/ \  S: X6 K0 R9 J" R, L  ask turtles [ set-car-speed ]' P6 x8 t# {* _2 s2 ^+ X) E2 I

( q+ i& a7 f: t* O+ \# |- K( C" Q  reset-ticks0 ~6 X' X; g( R, ]/ o: T& B5 ?% D
end
4 F) N4 Y6 M- a1 n# U  H+ w1 f# S
" D' b8 f- V- [4 X4 k+ G;; Initialize the global variables to appropriate values
$ T( u" c) J8 X0 D+ p/ z+ lto setup-globals' E7 I/ U7 x. G" ]( w8 B3 `1 B" \
  set current-light nobody ;; just for now, since there are no lights yet
7 b' U! e1 d' t1 m  set phase 0
' k4 G1 J3 ~' Y% }  set num-cars-stopped 0
! F% J7 {' @& Q7 |  set grid-x-inc world-width / grid-size-x) \6 ?1 h. I" n3 H) U0 k7 u5 c
  set grid-y-inc world-height / grid-size-y( j* V  r" d( p% g5 [. r

  p  y6 n: M/ C, \6 Q  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
& `! u0 d0 t# m' t! I3 W  set acceleration 0.099  A- j# G/ k& H9 G, s
end
' i  o% N% [! Y" h" {2 H3 o
; e; w& u- I' `2 ^; J7 r1 y% T;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
. H& T- `3 i  X7 s1 m# I! u;; and initialize the traffic lights to one setting
/ f% d* o" y6 v, r) P% Xto setup-patches
, Z9 _" P8 \0 T& y  y9 i  ;; initialize the patch-owned variables and color the patches to a base-color
) n  Q0 _. p, H# f! R% i; k  ask patches
1 I- v- G& I( ]) A6 @" {' a9 r  [
$ x5 j) \2 h) D. @2 e    set intersection? false
4 H4 a6 j& g1 H    set auto? false: Y8 Q0 k8 R" ^/ [  y' F
    set green-light-up? true1 B3 z& d' c& t' V
    set my-row -1
# E- A: c8 d( V( N2 }+ \. S    set my-column -1
8 |* @3 \6 A1 V7 N! O  n    set my-phase -1
  k/ J% R. \; ]6 w    set pcolor brown + 3
% L" t) E2 c- l# u  U: u% O  ]
9 a! V0 C4 O  v, k( Z9 K0 T' o7 _% c, D2 b. }4 e3 g3 F
  ;; initialize the global variables that hold patch agentsets
5 X4 _% O% \0 `2 d9 m9 A  set roads patches with  ?7 m- m: }4 Q9 [8 Y# e0 B2 q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
3 N2 c3 l& b5 t& Z, p' P5 O    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
% q' w5 H: h, K. Q- I( R$ l  S  set intersections roads with
6 O' \( ^" F2 U; V8 z4 W    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and* N, T( Q8 F8 }- j4 b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
* \2 F# u7 j$ E9 c# [
, L2 R  j+ D* m9 K9 l5 Q# T  ask roads [ set pcolor white ]- [8 O$ w) l  H& Z) h
    setup-intersections( K0 o/ i/ i& T6 t
end( c& ^4 j' m' F# w
其中定义道路的句子,如下所示,是什么意思啊?4 t( h9 U4 }6 X! A
set roads patches with# M$ ]/ e7 C  V$ r  {8 z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
* b% \2 a) d* {0 a6 d  }    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]: S% V4 `  W1 \# D
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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