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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。* m/ M- F3 M. W" x
netlogo自带的social science--traffic grid这一例子当中,
7 }4 _/ c8 Y0 C) qglobals
  t# T2 ?. d: A' T/ K; L4 u* T! r/ F- `6 T[% @2 C  f5 F  M9 i; X. B
  grid-x-inc               ;; the amount of patches in between two roads in the x direction
3 O$ h/ C2 r7 V5 R0 v  grid-y-inc               ;; the amount of patches in between two roads in the y direction
, C4 j& x) z0 C- |1 C8 O  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
' ?7 \/ z4 [9 W/ G* G                           ;; it is to accelerate or decelerate
# i9 w4 X6 U4 v+ b/ `' k# }1 Q5 E  phase                    ;; keeps track of the phase4 k' O# k: @6 g, \
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure- Z, ?$ V9 w1 p+ {+ V% F( R
  current-light            ;; the currently selected light" E8 k4 Q8 y) F" E

3 L* E% I8 D4 R7 D, U) t  ;; patch agentsets2 S) y+ k. ^% h3 u9 v
  intersections ;; agentset containing the patches that are intersections- x% _' u5 p5 W) F
  roads         ;; agentset containing the patches that are roads; i) ]6 E: \# t. ~" ~
]8 P; f$ O* e2 w' n; R1 O) P

4 }6 m8 r/ h8 I6 I; Gturtles-own' |$ t4 r5 B- N& T  p0 [9 y+ ~
[
. P9 j! z) k- I/ V: U6 F+ x8 J" X( V  speed     ;; the speed of the turtle/ c# t# S& Q) V8 `8 F
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right: d! f. ]2 X6 W: }7 G) T# N% a& R" }
  wait-time ;; the amount of time since the last time a turtle has moved
3 }2 Z3 g8 a, Z5 f' D]0 c, v# M. O  [

1 i- R4 J9 o& R7 B. ]patches-own- v% s% r+ _' ^: u
[1 v' `( H; U9 P: U
  intersection?   ;; true if the patch is at the intersection of two roads' `6 c$ w5 ~4 ^% K0 D
  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
- n4 T: l( G: C' j# [                  ;; false for a non-intersection patches.' E# R; B6 ^/ S6 F, [
  my-row          ;; the row of the intersection counting from the upper left corner of the
; |: n9 ?% d% k/ i3 U0 z1 q                  ;; world.  -1 for non-intersection patches.- T$ h5 Z2 L6 |: f  Z" W
  my-column       ;; the column of the intersection counting from the upper left corner of the! O# U8 V' F3 c) g0 u. T
                  ;; world.  -1 for non-intersection patches.
& O! ]8 Q$ ~& ?  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
8 z/ {1 P9 e) Y2 d  auto?           ;; whether or not this intersection will switch automatically., U+ O6 o  x- ]5 T" h3 E, a8 S
                  ;; false for non-intersection patches.: r, G* D( d* P$ ~+ ~
]
9 O4 \! j) d  Z% Y
1 f0 ?3 y  N  F
3 |" a! ^" D8 R& q;;;;;;;;;;;;;;;;;;;;;;5 j# H1 P* y* j$ `+ K
;; Setup Procedures ;;& V$ E' X% _$ U) y' d  l3 `
;;;;;;;;;;;;;;;;;;;;;;% X1 G4 ?' I5 D  P. A. p

$ ]0 K, T: l9 W;; Initialize the display by giving the global and patch variables initial values.
9 w; ?3 N$ T# y% b' R) S;; Create num-cars of turtles if there are enough road patches for one turtle to
; l% \, b' r2 L1 B, X/ f1 j. k;; be created per road patch. Set up the plots.
) R0 U! _3 a8 Rto setup
: E2 o8 v% `0 D" G' v  ca7 J& H% ~0 W) `  e1 Q4 ~$ w. c/ N
  setup-globals
  K" O% }4 p$ i4 G- q+ P* }7 j8 v( C: _0 f
  ;; First we ask the patches to draw themselves and set up a few variables! b% r) x# e- n2 I0 p# ~
  setup-patches- f# y' E9 x# t8 o& X
  make-current one-of intersections. I& k2 @) D' {3 j& h$ l
  label-current8 w7 O* L6 `( A! @1 U

; E& [* C9 M0 B1 H  set-default-shape turtles "car"
) L9 C! I) ?$ u% p: W* T, f, H: L7 s' D" U
  if (num-cars > count roads)3 R* e2 X! a5 P# R" u
  [
2 G5 u8 d( i; T) U+ ]* q) ?5 F/ d8 C    user-message (word "There are too many cars for the amount of "
6 i7 l; L, @- X; O                       "road.  Either increase the amount of roads "
* @% ^: R& [2 _# f2 m- C9 Q                       "by increasing the GRID-SIZE-X or "
# b2 [! x) n) ~2 ?0 D* Z6 j4 I! _) d                       "GRID-SIZE-Y sliders, or decrease the "3 g+ {# j' f; J7 R  L  ~; _
                       "number of cars by lowering the NUMBER slider.\n"
/ C/ B0 P+ K: S, O4 f3 R                       "The setup has stopped.")1 K3 ~4 T, N/ e$ ]0 _
    stop& [  h% C, g$ M/ N/ T4 t! N: v
  ]& @6 ?. w. [1 ^% C. Q1 K

5 M  S8 a3 Q- L' N) ~& o4 t2 u! Y  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- p; t7 p6 B- W% Q5 b2 J7 L4 S9 y! j- L  crt num-cars
+ A& C% Z) L# P3 b4 v- ?  [9 E5 b& s1 G7 x4 n* n0 a) t& [' p6 m
    setup-cars
8 a+ b, Z$ m- ?* W    set-car-color
* Q! O& L0 d' S$ b6 x  J    record-data
$ f  g7 i$ e, {" N  ]6 n/ J- a. ^2 c5 u* [5 P+ S, r

8 ^$ o2 p( |+ y" ?  R. j# d  ;; give the turtles an initial speed9 H3 L6 l4 C- G! J3 M
  ask turtles [ set-car-speed ]3 o4 n1 O1 Z; ?( y2 }! b' Z. v' Y3 y
" a/ E, L& X  S# U% m$ ~  j
  reset-ticks4 H5 P% G9 e' p$ x
end
: Y+ K( f: z5 z# Y, T7 J0 }
/ O  l; ^; l$ ^* q/ s8 i: _5 Q;; Initialize the global variables to appropriate values
" V) d$ c% D$ D6 f" ~7 Z# rto setup-globals) j/ g% h; R8 S' R8 S) S& v
  set current-light nobody ;; just for now, since there are no lights yet
5 I1 k. S+ E& C  V4 o  set phase 07 i. G* L/ C! R7 l; h9 }/ L- C
  set num-cars-stopped 0
( ?. |! M8 I( x7 N5 t' B  set grid-x-inc world-width / grid-size-x4 w7 L/ i1 L$ l! L& X, Z4 K
  set grid-y-inc world-height / grid-size-y
- u1 }/ N7 z; y' y! t
  G! t; U' R9 G: `, y9 e  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary) e0 v. h, G, {+ x9 d4 E8 p) m  d
  set acceleration 0.099" z7 w6 y! I9 v0 t5 P' U0 l
end! T8 ^# [, e  R$ I0 \! T% g
; v( G2 B5 d! D) L2 K! k5 L9 F" q" u
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
* c1 K& f" i  r;; and initialize the traffic lights to one setting9 o* ^9 C; o; F- b" D
to setup-patches
% j' v5 v+ z; E, P: n+ w  ;; initialize the patch-owned variables and color the patches to a base-color8 s" y& k: `2 T! q: B- g- ^
  ask patches
* x/ z$ C3 n' B  [$ Y0 L9 M! ~  U' _
    set intersection? false
# b( s$ l7 y4 R. S    set auto? false! ]5 W: o. I2 c4 P# v, c
    set green-light-up? true
% m4 h3 c- d" l( r! a$ Y    set my-row -1
' D* G* a# ]+ R7 h    set my-column -1
, l1 _' g# Q9 q' K0 S0 E+ n, n    set my-phase -1- R. E3 c7 [: Q
    set pcolor brown + 3
  M( m( Q" n" H  ]
6 L- n3 j+ k( m2 ?/ T# v) t9 k  s& G/ Z- e4 z( d
  ;; initialize the global variables that hold patch agentsets9 [$ o1 R8 S1 T! R  p) ?
  set roads patches with
- {7 d% n5 z  F2 u: r    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 s. g4 H( a8 ?  c$ `0 r' f    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]9 z) W6 A7 n7 |& q
  set intersections roads with
( Y: C! h$ {1 N* }7 g9 t    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and0 W% j: {* n* j3 J8 A9 Q0 L! d
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& }: o3 J& `; A7 s. L/ O$ E  n* x$ Y
8 L, ^- o) u! K# E  ask roads [ set pcolor white ]6 U1 q/ a6 R! q6 d/ o5 V% Y
    setup-intersections- r: r0 O, b" ]& ]9 S  j8 }
end
, [9 l/ d# S; ?) Z; i其中定义道路的句子,如下所示,是什么意思啊?6 b$ w$ B' ?+ m
set roads patches with
- k* T5 m- W" M. j6 p    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or9 z  B% Y  C' _, P  o" Q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
; \$ v7 J8 O4 g( 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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