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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。; z  r7 L4 ?3 M, o) l  Z  t
netlogo自带的social science--traffic grid这一例子当中,+ W3 b/ P4 Z8 t7 z1 Z* [( w
globals, u  j2 a% A- R3 m
[
$ e' g, k" x. a: Y8 [( v6 t& Y  grid-x-inc               ;; the amount of patches in between two roads in the x direction
8 s' J0 m( z) _, m6 S  grid-y-inc               ;; the amount of patches in between two roads in the y direction& [: p; v& j/ s
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if/ `! g0 w6 O$ \
                           ;; it is to accelerate or decelerate
& P5 B" @6 f' ?0 b- Y  phase                    ;; keeps track of the phase( R7 {  @& Z/ x; O' N  C
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure
. c, g7 i/ D* @' }6 `+ v( ?  current-light            ;; the currently selected light7 ^) o; N3 j& }/ N

! ]1 }9 F+ u1 h( j9 b, ~4 I  ;; patch agentsets) d% _2 |& P( C' `6 a  n
  intersections ;; agentset containing the patches that are intersections
+ m& t. O1 w) r5 u  roads         ;; agentset containing the patches that are roads. z: @' S$ W$ S2 H* z8 d
]! A( G* p0 k7 W! ]  D
. U" d4 F! u. R
turtles-own7 U7 a* ~0 A# M  u4 ]9 |2 c2 H
[
6 N" v3 P8 Z8 t5 K# l. T  speed     ;; the speed of the turtle, Z, |6 T2 f( d9 z
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
& f* }+ x& ]; U/ w' a  wait-time ;; the amount of time since the last time a turtle has moved
+ I$ ]  x' @3 `3 p8 P]
* x6 H+ o9 t: @: x+ a5 n' k; P4 P/ B) Q2 A- X0 `
patches-own
5 e. K) ]; r6 d$ n" w7 Z[
7 T- y' H2 H6 f( _! m; t. a3 k  D  intersection?   ;; true if the patch is at the intersection of two roads
0 s* s, b: |, A8 S/ z! k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 |' a2 [: o# {                  ;; false for a non-intersection patches.' H$ r* C0 V; B
  my-row          ;; the row of the intersection counting from the upper left corner of the! [% L2 ^! ~/ T
                  ;; world.  -1 for non-intersection patches.
0 K( F( ?% @; W% R9 e& _, N5 n  my-column       ;; the column of the intersection counting from the upper left corner of the
* J: a5 [, Z1 u1 k" F0 A. Z0 s- I                  ;; world.  -1 for non-intersection patches.
' U! W0 [# R# F  |  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.+ K5 }9 R# E4 l( ~" g% U
  auto?           ;; whether or not this intersection will switch automatically.
$ }& v! K3 I% P* K/ B                  ;; false for non-intersection patches.
: d% c8 ^# O' O0 _# N( B]
# w8 p5 a6 q& j
3 n7 m  X. w, h8 @' M/ ]! _) Z0 |" G  h1 U. d2 g: L
;;;;;;;;;;;;;;;;;;;;;;9 U# e; A9 O; {1 g6 _$ F! x7 K/ T
;; Setup Procedures ;;% b7 k6 {  y7 I
;;;;;;;;;;;;;;;;;;;;;;( A- J! q! V. p, |- |# J3 \

% t6 |5 v% o* `" z7 e;; Initialize the display by giving the global and patch variables initial values.
& [8 M! A: G3 Q! e, |" ~;; Create num-cars of turtles if there are enough road patches for one turtle to4 b* D6 M' k9 a# h' D
;; be created per road patch. Set up the plots., H6 q- o& ~/ g9 o; ]% J
to setup
( c! ?# R/ v. L& e3 C. v  ca6 Y5 q6 [; S6 \& u2 N
  setup-globals0 ^5 k( \6 W. i3 x

' `4 Z) f2 F: R% v1 u( H2 Y8 e  ;; First we ask the patches to draw themselves and set up a few variables+ G# r3 n5 u) G1 s5 i
  setup-patches
6 r, C4 O* |0 C  make-current one-of intersections7 |: T) U* T5 l4 p4 P' {
  label-current3 u5 W* t4 U3 l; \! b

# P/ [' T. h( a, P, o7 e& |  set-default-shape turtles "car"1 H4 Y# a% S- @5 Q
  v' v( E0 Q& D1 ?" x8 C
  if (num-cars > count roads)
% J: t4 n/ g  }1 W7 H; C5 c& m  [: I1 V/ Q' i( l8 w! v! O
    user-message (word "There are too many cars for the amount of "
7 Y/ T5 ]1 r, ]4 w8 K                       "road.  Either increase the amount of roads "& R9 t; J" o: N1 B# W
                       "by increasing the GRID-SIZE-X or ", d, s+ l2 W9 Q4 l+ d
                       "GRID-SIZE-Y sliders, or decrease the "( w. b) }+ X; _
                       "number of cars by lowering the NUMBER slider.\n"8 c$ v8 c0 V/ j& E
                       "The setup has stopped.")
: [% Q6 E6 v$ v* W  u2 |5 o    stop
& n# t* h" a& w3 X3 F' K- W# v" m  ]
+ K$ n. d9 W6 |* y; B) Q2 E( K2 {6 q: J: f
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
, ^2 d/ O0 @* U' z  |, ~) W  crt num-cars* G4 Q9 X, Q4 v5 W  u! z0 ]
  [2 W2 c$ K" z6 @% h2 {
    setup-cars
, k6 }. l: C  ~/ u9 }& c    set-car-color; t* L' @% b) d( a* M
    record-data
9 Z4 F7 L. k2 ^* n( e9 h# {* t( R  ]
0 Y" C1 ]3 J$ j% }# N4 |
- K- Z) y% G: h1 M2 f8 p  ;; give the turtles an initial speed
  q3 l9 M- t8 H/ [  ask turtles [ set-car-speed ]7 L9 W9 _$ ?+ l% Q
; O' e  ]8 Z  p1 e& B
  reset-ticks
& G$ ^9 @# [" O3 E7 X4 m* uend
5 v- U7 ]; R) f8 w. r6 \! c( S/ x4 u" a, ^5 @
;; Initialize the global variables to appropriate values0 o7 D4 S" `/ _- F
to setup-globals
. H/ [3 B! f' m, d( R( Q  set current-light nobody ;; just for now, since there are no lights yet5 g& P2 G/ X3 S% ~# s0 n
  set phase 0" b8 S1 N/ b. c. [2 D
  set num-cars-stopped 0
. x* Q& x& w9 i4 X& i7 s  set grid-x-inc world-width / grid-size-x( T9 P6 {* v  H4 O$ x
  set grid-y-inc world-height / grid-size-y
! e- Q6 V' ~8 C/ _6 T$ I* N8 W' Z- }7 R) v3 v3 H$ g
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary8 x6 B! X9 v- y; e
  set acceleration 0.099' o5 h  B; X( S7 y0 e
end
& h7 G" r% F! f# r; J2 E; T( ^& T5 ^4 p/ Z* L2 }8 N
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,- b/ A7 |0 R4 E3 {: M  `' K( p7 J4 v
;; and initialize the traffic lights to one setting
8 q. {, q9 t' e2 v$ mto setup-patches& q) ]! M4 t$ ^* f, o4 f
  ;; initialize the patch-owned variables and color the patches to a base-color
  w$ ~' n$ E# k- Y5 B/ g& |  ask patches4 Y, G6 U1 B$ k* t& M' I
  [) {2 X' ~7 E) h& {2 o
    set intersection? false
4 M0 }! T6 L! v, `8 k9 j    set auto? false
$ A1 A/ Z- E& I+ |$ P    set green-light-up? true  c# g8 e+ T8 Z; E7 A# z: t
    set my-row -14 F5 W% l7 X+ ^% i/ r8 K
    set my-column -1
( b4 Q3 o( w) a' `    set my-phase -1
% d8 Z( M( Y' p! t; L    set pcolor brown + 3% l9 n$ F0 B- y1 ~# a% j7 n
  ]/ C7 U5 |  V' n: b

( R6 E- z6 J2 R; P/ s8 r  |# F  ;; initialize the global variables that hold patch agentsets6 ]# l1 ?/ }% O: ~& u
  set roads patches with+ K5 z) u2 [  t& Z
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( _6 @2 q  }3 ]! o
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]1 I6 p) C- p# E" c  J
  set intersections roads with
& W6 i& c- i/ G9 }7 t" q: N$ m    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and
7 G  A; F- T4 `6 [+ E! l    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
) O9 D! X) L- d- h  w% E6 g% j- F/ H5 Y! g1 W* A/ c
  ask roads [ set pcolor white ]
8 d( d! w) h: d& Y' R1 ~+ z    setup-intersections% H3 G% M4 l$ u% H- y/ f
end4 \& ?/ L: D3 S$ [1 b5 X
其中定义道路的句子,如下所示,是什么意思啊?
2 G( r) X* ~# Y1 V: K set roads patches with" N1 k2 r' u7 `. ^
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or( O2 P8 S  E1 d* R1 A% f* Y
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& V+ n' [6 h+ }6 T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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