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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。4 Q, x4 G+ |$ z# d
netlogo自带的social science--traffic grid这一例子当中,$ r2 Q0 r% n" I
globals' g" ?. _1 S& @4 h$ k3 A2 t$ J* @: u
[
6 \1 l+ }+ b6 C/ P2 b' }- }  grid-x-inc               ;; the amount of patches in between two roads in the x direction0 `6 X  l0 p' J$ q- t2 `
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
. w' t8 b# O! X. r  T( j  acceleration             ;; the constant that controls how much a car speeds up or slows down by if  L& L8 h/ b" {0 M
                           ;; it is to accelerate or decelerate/ T/ O, Z% l0 v, w4 k, i4 T7 z
  phase                    ;; keeps track of the phase
1 N9 D8 j# o. _! C  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
: B) S. W2 B3 s3 M9 a  current-light            ;; the currently selected light; @( a' O2 D/ k3 a

, g* ?& x- a! G% z+ O, Z  ;; patch agentsets
0 r' L" G  V) B& `7 d  intersections ;; agentset containing the patches that are intersections3 j9 E8 g5 D6 @1 I
  roads         ;; agentset containing the patches that are roads# _& q1 l0 j1 E1 h. l3 t& j8 ~4 [
]. H/ |1 N0 E( B0 m
5 J. W* r  ~! V. ^$ T
turtles-own
6 g( I( g# t/ g4 a3 a9 A; U[( v1 c6 m) q( v9 c! X0 I& z
  speed     ;; the speed of the turtle5 G9 G! A, ~) N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right& {% x' j: {2 @! c- ?' q
  wait-time ;; the amount of time since the last time a turtle has moved
6 ~/ K) l8 P8 K, f]1 f& w; X/ X$ U/ ]0 j/ F0 f5 t- I

  Y! A" Y2 F/ u2 k% y: i4 Y$ wpatches-own0 V; I  c& M7 _8 S  z: t% b
[
9 U0 M3 @3 a" ?2 z- d  intersection?   ;; true if the patch is at the intersection of two roads
% m% Z6 {" o+ {0 p' b% w' x  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
" j* S" c1 R4 Z7 m; m$ F                  ;; false for a non-intersection patches.
2 W  i6 \- _  V+ l& b! S/ I, `  my-row          ;; the row of the intersection counting from the upper left corner of the
4 T0 f' Q7 y6 Y. \  o: t! U                  ;; world.  -1 for non-intersection patches.8 S1 i3 S7 ~' s, i
  my-column       ;; the column of the intersection counting from the upper left corner of the% @0 u: F+ \" B2 N
                  ;; world.  -1 for non-intersection patches.
$ M: t* _9 N8 v& F" u  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.* w8 k3 ]1 ~, e! |
  auto?           ;; whether or not this intersection will switch automatically.
! Q) {5 M1 z+ |6 Y: }" ?                  ;; false for non-intersection patches.5 L0 ?# f) z2 _. {, H, c  Y% R
]
0 t9 I' ~0 O% V
* g* H- S  B- B% D
& ]6 x) H6 p+ D8 p- I8 D;;;;;;;;;;;;;;;;;;;;;;: B+ a) ^; v' T( q/ t6 p
;; Setup Procedures ;;
2 [" f+ e; k; U( p+ ^5 @# F;;;;;;;;;;;;;;;;;;;;;;2 A& \" L3 J/ N9 M/ m
2 i) D1 z/ M+ R4 Z
;; Initialize the display by giving the global and patch variables initial values./ r  w! V5 [9 A' J
;; Create num-cars of turtles if there are enough road patches for one turtle to1 L& F/ J5 G8 G  Z# Q
;; be created per road patch. Set up the plots.
! N- d* E$ e! [to setup% h0 x  c5 R9 D- u
  ca* B" p) \, f4 @+ |4 f' o: b0 y; t! D+ t
  setup-globals- ]& R! W& L5 L5 D3 ]% ]( e3 ^( k
0 j/ ^+ A0 n9 l7 x) |5 |- U
  ;; First we ask the patches to draw themselves and set up a few variables
$ f% p) a* ]# ~* @- A  setup-patches( c' `; n& m, t* E2 {) @1 O& ^
  make-current one-of intersections
9 V" V) A2 ]; }: i  label-current, x6 h8 t* M- r7 S

( x4 F. U5 f$ a  set-default-shape turtles "car"* Z. k% t5 E  l5 I* P. z
) L" l) q: m0 n! @5 C3 Z
  if (num-cars > count roads)
6 f: {8 M  t# x* F; j) U! q+ @* r% H  [
( v6 J. X& s) I/ n0 ~2 w4 s    user-message (word "There are too many cars for the amount of "
. ^& S+ T9 X5 u4 O                       "road.  Either increase the amount of roads "
/ }& Y3 g* u: S: o0 n8 F& p$ D% Y                       "by increasing the GRID-SIZE-X or "
- g4 s7 y0 h3 L$ z# b, m! K/ C6 X                       "GRID-SIZE-Y sliders, or decrease the "
  q7 Y3 T/ o- d9 M% g5 r0 }                       "number of cars by lowering the NUMBER slider.\n"' J6 e% d+ X* c" U  J% E9 f" I
                       "The setup has stopped.")
# }, A* p6 T( A. k! g# x9 r' S& f    stop
5 ]* D0 b( W. x- h: |* ^1 |, w; z# _  ]
9 I- D+ K6 c, r5 n
8 ?% e; G8 g, a1 e/ ?* ?  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% r# e$ F- o% m8 `! z  crt num-cars7 m) X3 a+ L) ~) m
  [
  L! L% A' g7 r  Q% y  t    setup-cars
+ c/ w3 R2 L' {+ R2 u% L! W    set-car-color
. a- E* L2 x$ R: S3 x8 ?# a- `    record-data
  w; M; \" q: R/ Q) d1 M' P  ]0 h$ \. W/ L, }9 w" H& R; b2 R% |( I

, h  `! l! l7 m: z% T4 z: Z/ v  ;; give the turtles an initial speed8 r3 l4 L9 ], J1 a4 ^8 T( c
  ask turtles [ set-car-speed ]
, r% n  l5 o. u4 N! X! s* I- G4 n* B/ \% F' N& l2 C
  reset-ticks
# ?4 a2 G$ v$ Gend
- {3 k+ B% q7 C1 e- J, m. V+ s  ]& n0 ]  O
;; Initialize the global variables to appropriate values3 g# L7 P3 a+ l; N0 _1 p' g
to setup-globals  O9 \! n/ B  I+ M+ p
  set current-light nobody ;; just for now, since there are no lights yet9 f6 l5 D( g& B. A  R" w' B
  set phase 0, |( H( ]% f9 j3 ~+ P& j, v: M
  set num-cars-stopped 0" }) `- g* a' G
  set grid-x-inc world-width / grid-size-x" S' F2 H- W' [( F! H6 B
  set grid-y-inc world-height / grid-size-y1 M5 M$ I+ A) u% B2 c

$ r# p/ @( p( H4 }. _; G9 F3 j  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
$ g2 T9 q/ ?- V0 a) Y. H  set acceleration 0.099
5 D$ o# C) d: L# cend
/ d* t3 L* ~4 I! C; ^! }2 M
4 X. r/ e0 j) P- }: [1 B;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
  `1 F  s: ^$ _6 y+ L& l$ H0 O) P;; and initialize the traffic lights to one setting
1 H' J& u0 w, sto setup-patches( \+ j) E) M3 r9 o
  ;; initialize the patch-owned variables and color the patches to a base-color3 b+ R. s  `! M4 S  }
  ask patches& G" i7 }2 v+ G6 q' G
  [- k. R+ _( n; L6 s1 x1 q' ^( x
    set intersection? false* Q# j. {2 m8 ^" ^- t
    set auto? false# c2 c, b' U+ ?8 `% D
    set green-light-up? true
$ ~+ E. w% L7 S/ E! X0 a# d) S    set my-row -1( f5 Y! ?$ D, B% @6 x
    set my-column -1
# t/ W/ f9 X& U& j% r( C# g) ^0 I    set my-phase -17 T8 u8 P: C( g! a' m6 \
    set pcolor brown + 3
; y' r6 f: b3 R% X8 g; X  ]- t. {6 v; }2 U* z0 N2 t' s
: r( C1 @! s0 H4 \
  ;; initialize the global variables that hold patch agentsets( u( d5 j0 J3 s0 I# [1 @8 l
  set roads patches with
: F* L2 G- R* V7 j- J  _; x9 v7 t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
: C- |4 p8 d# |: m) d$ W    (floor((pycor + max-pycor) mod grid-y-inc) = 0)], {3 `' q8 @+ l! @& a/ u& w6 l6 z& n
  set intersections roads with! X7 f) s1 ~' b% [/ Z  S+ A
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
0 {) P! [  A+ a+ v' b% a- K    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
9 n  Y5 B: i$ H* v' X$ m# P8 ?" U% [% G6 U# v
  ask roads [ set pcolor white ]
% n  c% {, i+ R    setup-intersections1 Q2 O6 y3 X: V+ F9 N: E3 T5 w) ^
end  g7 N6 Z" W, U! g( M
其中定义道路的句子,如下所示,是什么意思啊?, }# I; S' j& @. v/ ?
set roads patches with: u' I( F4 [  ?  A9 B9 \+ y& ^3 |  Q
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or& q$ K; t: E$ c9 b
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]8 i9 c; p; k& Z( e) L8 E5 y
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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