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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。
$ w+ {6 K3 n: i) E- enetlogo自带的social science--traffic grid这一例子当中,
' j* W% L- G% j6 b% g! Zglobals3 J+ Z8 L- i6 _6 n! ?  d6 w
[
9 q# l; e5 k$ r7 f) O  grid-x-inc               ;; the amount of patches in between two roads in the x direction2 G+ x4 G' s9 J( ~
  grid-y-inc               ;; the amount of patches in between two roads in the y direction
5 Z! n- j) d# l% j' F4 L  acceleration             ;; the constant that controls how much a car speeds up or slows down by if; d  L: d8 ]( K9 H6 Z5 f" A
                           ;; it is to accelerate or decelerate% g. N! y/ I' S9 K
  phase                    ;; keeps track of the phase+ E8 P; N$ \9 l0 G' Z
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
$ b7 U$ t7 L% J" U) w7 _  current-light            ;; the currently selected light
- a" T9 h9 @) G8 i1 G' L6 ~$ u: x# Y) t! g- r6 z7 e: l" P
  ;; patch agentsets
/ M% W+ H; Z) U! j) E6 V( x  intersections ;; agentset containing the patches that are intersections
; e5 I! E6 k$ g2 q  roads         ;; agentset containing the patches that are roads
' o# t! @! D; r1 K4 H]- S; j" G" k% j/ [5 g1 d
9 F# B' r  f- [% t
turtles-own
! k+ b5 u0 V$ Y! O9 i[. a: {* f9 Z/ J, `
  speed     ;; the speed of the turtle( b6 t2 ~  ]# |7 v1 @  [; D
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
# H4 ]) G' k8 m5 f& w  wait-time ;; the amount of time since the last time a turtle has moved
/ f/ Q% p9 N3 U8 a7 [( b+ {]5 F+ W- u3 w4 r: K# {/ H; x
" }+ Y7 ?+ d# C7 P. b! K; [
patches-own$ E. Z. R, G! H# Z1 g
[
& z7 u! L2 }& K/ @  intersection?   ;; true if the patch is at the intersection of two roads
' O) Q2 d( D2 Y: l$ L  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
9 Q. f8 r. q' E  l4 H                  ;; false for a non-intersection patches.: S' U% @4 F. B% F9 ]
  my-row          ;; the row of the intersection counting from the upper left corner of the) w, _  o0 D! K$ R
                  ;; world.  -1 for non-intersection patches.
! ]& {0 x* H4 e  ~  my-column       ;; the column of the intersection counting from the upper left corner of the
) a; [0 ^( m9 w/ M                  ;; world.  -1 for non-intersection patches., e$ S3 b# q6 k. n
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.
' m; I4 C) w0 s: p( m  auto?           ;; whether or not this intersection will switch automatically." B) I* M2 m+ ^* @
                  ;; false for non-intersection patches.
2 \/ \! O8 o) F( x1 W+ A]) _9 N" c9 w0 e' U4 e2 `* Z
) h9 H0 A& h; u& t# X9 h

  y4 B2 c$ d* G: B;;;;;;;;;;;;;;;;;;;;;;
6 u, o7 m# f& ~3 Y8 K( c;; Setup Procedures ;;0 q) w4 r# J) }5 W9 G
;;;;;;;;;;;;;;;;;;;;;;$ W9 t3 v1 h! y; K: `/ h
1 l* A( x7 @  f+ ]" Z' {
;; Initialize the display by giving the global and patch variables initial values.
# t9 s' v0 m( C7 m( o;; Create num-cars of turtles if there are enough road patches for one turtle to
/ ?2 K, u6 i- y- ]; R;; be created per road patch. Set up the plots.6 t) `$ J1 Y% f
to setup8 \# Z# B" Y1 w
  ca
0 M2 A4 ~8 l9 v! M6 C6 S5 ~  setup-globals& y3 F) T5 Z  M" L/ A5 N
+ F9 t: O1 V+ O& k' F( s3 ~* @
  ;; First we ask the patches to draw themselves and set up a few variables
7 q3 n+ i, M8 V  setup-patches+ H+ t9 R& r; Z. v
  make-current one-of intersections
  K3 E" C# h0 K  label-current
$ e: Q1 F& _5 g; G2 ~
+ c$ _4 n) i% p! o, Q9 Z+ N5 \, z# F  set-default-shape turtles "car"& {- P2 ^) I3 M4 {
; P: b, }' u! @2 Q9 r) U3 {
  if (num-cars > count roads), ]$ b* f& W! K" ^, ^1 ]( ]
  [
. I1 ~  P( B: G" U" J# G2 K% r5 M    user-message (word "There are too many cars for the amount of "" R- O0 O7 _5 L7 X! H: c* V! i
                       "road.  Either increase the amount of roads "
) H7 J! l- S; {0 ?# x" V                       "by increasing the GRID-SIZE-X or "
. d  D7 \( \& y, M& C4 _  b; y8 ?0 [                       "GRID-SIZE-Y sliders, or decrease the "
5 i+ j/ U6 @, f; @, @6 E) h                       "number of cars by lowering the NUMBER slider.\n"
. ^3 P4 a2 Y* d# T! T                       "The setup has stopped.")" `7 V2 Z3 h) y' f+ t6 d5 F, o
    stop
- z6 ]  U5 O2 a( M  ]
4 W/ ]8 V: R' F( O
1 V4 M$ d3 K- ~  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
- L1 P5 C2 S8 Y- v. Y: a4 r  crt num-cars
: ?* n, _. v9 G2 d1 g/ t0 N! j  [! B# e+ m+ O+ u! Q
    setup-cars" q8 L8 Q4 b& `" O, }
    set-car-color
" ~8 [3 D$ b" d$ S  \2 a/ V% y    record-data& G) V: f% ~2 M" M8 y+ U$ P6 E
  ]& g8 h' a. ~# A; n7 q

: E& z7 L* f* z9 c" a) b+ u  ;; give the turtles an initial speed
% X' d$ D* X6 U) z0 \+ l. b  ask turtles [ set-car-speed ]" i2 n: ?4 n$ B, B" }( H
0 ?: ^( \- u1 b; d2 p; t, h/ o; X
  reset-ticks1 D% E8 P7 W" Q0 Q" J* l# W
end
6 m( l6 X& F& j
5 M9 i! x" h  J$ r- b9 p;; Initialize the global variables to appropriate values* V; U2 _8 p, ^5 V- c3 q  U' D& F
to setup-globals
- E# l: v- T* }2 d  \  set current-light nobody ;; just for now, since there are no lights yet; i9 u8 k* s. E" R
  set phase 0! R% R9 c0 [- A5 C7 b
  set num-cars-stopped 0
  E7 V) ~( \& B% h: P5 M  set grid-x-inc world-width / grid-size-x; ]( I- ]9 C! `9 A
  set grid-y-inc world-height / grid-size-y
- I# ~* f& n, L2 s+ N3 k- }# W9 \- d( {! A
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
; ^5 J6 c- G6 [3 n  set acceleration 0.0991 v$ t6 D7 G# U6 ]
end
" b2 Z8 a" J' u  [4 d" ]% z# p, p9 T, n8 x' k* O$ Q; A
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
, I: [; K- x* H# I: Y1 e;; and initialize the traffic lights to one setting
6 Z: E. t9 u8 J" y0 J' F; `to setup-patches" h; z; l6 l& G6 {& h. n
  ;; initialize the patch-owned variables and color the patches to a base-color0 ]2 y0 U9 b0 V
  ask patches" x! O8 C8 _; n0 W' w- ?* a0 S: l/ u: M
  [$ v' N0 i) V2 ]! Y& F& Z( I6 o
    set intersection? false& m* ]: \" w' D! J! ?. s
    set auto? false& Z( |0 l  ]4 R) j1 R1 w% N
    set green-light-up? true
: w0 i* V% q7 g+ ~/ K    set my-row -1
; J# f( F$ F" C- ^9 A  T7 n5 |    set my-column -1
% L- h" ?; f  A7 ?  _$ \0 P    set my-phase -1
" m9 \3 S% O- g    set pcolor brown + 3* b( |5 Q8 L, E6 c  p7 }
  ]
6 D$ ^. s/ a9 ], U1 I2 n
6 x5 `: R; ?  |$ C* X" X$ S: S  ;; initialize the global variables that hold patch agentsets
2 Y  j0 N9 @$ m0 e! }5 f' g  set roads patches with" H3 |! c. O! t! C* ^! J( l6 k
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 s8 Y/ x0 E; _6 y' `    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]' y0 h% x) u/ o. t
  set intersections roads with
/ n; `8 \! d4 s8 U5 I4 N9 ?    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
. s1 ?# S  H. R3 e* i- N* ~: p$ a' y. ^    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]$ H, |* H1 n! |+ \7 d. t$ p+ N
. A/ h. j4 @! c( @+ F' h+ ?! d
  ask roads [ set pcolor white ]' S% Y4 _3 Z" k" v( Z
    setup-intersections
2 k! A# a0 U* ]6 v% wend
" D9 H9 }/ b8 n* J0 ]其中定义道路的句子,如下所示,是什么意思啊?/ u# b% h& \9 b- B1 f6 o
set roads patches with
: i+ q+ k3 b* m2 s; z% }$ s3 s    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
8 c; _; B9 j. v! w    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
0 M# Q" O+ h, u( 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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