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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。% p% R$ R2 h1 F) F' i# o& O
netlogo自带的social science--traffic grid这一例子当中," p5 `8 Q" d2 i& X8 A
globals
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  grid-x-inc               ;; the amount of patches in between two roads in the x direction# d; V* ~( I! T; {- H! z& W! n. }  J
  grid-y-inc               ;; the amount of patches in between two roads in the y direction  _! _" r4 g7 ~& |; o6 k# l
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if6 \$ z3 e+ M% D( y7 L
                           ;; it is to accelerate or decelerate
+ _: r. Q; e# j0 E$ h6 ~7 J3 ?! \  phase                    ;; keeps track of the phase7 {8 `* `2 f( s5 M# g
  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: Y/ B4 ~9 P) r" k' y
  current-light            ;; the currently selected light
1 G, k+ U: l" r7 L9 N5 N& U' I: P9 |
  ;; patch agentsets
4 u, i1 p; n5 U( L8 q) e  intersections ;; agentset containing the patches that are intersections
3 h. O# P: k( _+ a: C; \  roads         ;; agentset containing the patches that are roads
1 T6 {$ m' h! q5 V3 R1 z]
: y! v* X9 p% b- b! ]' ~& a( p6 d0 U2 V( ?" b, h
turtles-own7 L3 Y! |0 y" D4 [9 E( |
[2 P8 |! G! B( i% j+ I
  speed     ;; the speed of the turtle7 ]0 G" q! v/ E( Y8 e; L5 N
  up-car?   ;; true if the turtle moves downwards and false if it moves to the right0 ^2 l% _1 ^( i$ p
  wait-time ;; the amount of time since the last time a turtle has moved$ K$ {- h+ I; b' H6 ~! i. n
]
, w- N7 L' g: F( `, Y+ O" M8 B+ H7 c
patches-own/ _; e1 t6 l% j6 _/ }  c/ W* B
[, H0 A* {& D% ?! O8 j, _! N
  intersection?   ;; true if the patch is at the intersection of two roads
+ b7 r, [6 ~+ \; k  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
4 K3 W  b& g+ V! m, o  J& t                  ;; false for a non-intersection patches.
4 I( p# h; z" U1 @8 \4 D  my-row          ;; the row of the intersection counting from the upper left corner of the
: p" s* p9 n% c2 B+ P# F+ V$ P2 ?) I8 d: S! F                  ;; world.  -1 for non-intersection patches.
' R4 ?! H. n  c/ L& ~1 Q! |' F  my-column       ;; the column of the intersection counting from the upper left corner of the
4 x% T$ }# t2 @# n6 c; B  i% }                  ;; world.  -1 for non-intersection patches.% d' x" _# h- a. E7 m
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.0 Z, B( ]' J) Q+ e! Q( p% g7 B7 @
  auto?           ;; whether or not this intersection will switch automatically.
! C5 C0 Z& @' [. l( L' I7 W9 v                  ;; false for non-intersection patches.3 u* z* G( c& G, W# r) j) O
]
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;;;;;;;;;;;;;;;;;;;;;;
9 R2 N% n+ A' W;; Setup Procedures ;;3 {" I0 K8 `8 i2 B; v- M) w
;;;;;;;;;;;;;;;;;;;;;;
# m- S# N3 V1 n: s3 \+ X5 x( R/ [" {1 U0 O7 [' n0 r
;; Initialize the display by giving the global and patch variables initial values.
, C! f% ~8 s+ G1 L% \. T% W;; Create num-cars of turtles if there are enough road patches for one turtle to
9 J- k% D; K$ R  O% d  q- p8 h;; be created per road patch. Set up the plots.
3 g$ g( Z7 O: l- lto setup
$ Y! U3 P, Q- @0 t  ca
: o; o; M! k8 K2 @# \  setup-globals
+ l2 i0 C* z8 F1 u5 x! U+ u$ J& O+ N$ u$ i
  ;; First we ask the patches to draw themselves and set up a few variables; D) K# \; Y  ]/ ]; ^# b# f$ h
  setup-patches8 z' {: R. m" G, K7 B2 R+ r: n9 A
  make-current one-of intersections
) {) f+ @9 \- e5 f  label-current6 s6 h% J6 S$ L$ `: K& i. [

+ ^4 ?# R5 z, F8 G# J: N8 w  set-default-shape turtles "car") S4 X- R+ w& p! H
5 O! w/ r9 s6 {& Y# H) Y$ I
  if (num-cars > count roads)
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    user-message (word "There are too many cars for the amount of "8 R; c4 ^1 N/ P4 s4 X# F! V* \
                       "road.  Either increase the amount of roads "2 Q3 w0 Z8 |4 h
                       "by increasing the GRID-SIZE-X or "0 H# O. g0 z+ {: ^, V" c  c% _
                       "GRID-SIZE-Y sliders, or decrease the "
( n" b% y: S9 L( y- D                       "number of cars by lowering the NUMBER slider.\n"
3 C0 a0 [: E% k$ q2 \" h$ S) s; [                       "The setup has stopped.")
- X- M$ C9 {6 e" R  T- z! H    stop" [# O, s6 _3 q9 Y( r9 G
  ]
) n0 Z; G- w; r3 h1 x
, F" c5 v0 X, Q1 h2 }; ~: J4 S  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
' f, h+ v; [2 ]8 t  crt num-cars" N/ G9 i+ d/ n
  [
7 G- ?3 D$ A& r7 Y4 F/ k    setup-cars
0 T! W2 n+ j+ i0 \    set-car-color7 j9 Q( G4 j9 G1 i3 z8 q7 v% v( K
    record-data
% q# G! w3 `- _6 u0 ?8 M2 ^  ]
% o( u* @, K: f1 }3 I0 C! ]( _0 Z0 h" V
  ;; give the turtles an initial speed
" z$ U$ S( |, ?, ^, W6 P4 n  ask turtles [ set-car-speed ]
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+ Z' k  e' }- t3 c( i* ^" ?  m) v" f  reset-ticks
) u: M# v: D. g- b; u( a. @, B/ Y7 Mend. ]* p3 i1 O* _1 S7 E! ?

9 T6 B9 J8 ]: q  Q;; Initialize the global variables to appropriate values
( V% s: I6 X3 [. u' Lto setup-globals! G, s3 Q8 A1 y7 U5 O: n0 d6 n
  set current-light nobody ;; just for now, since there are no lights yet
0 _$ M  Z+ ^/ e* k  set phase 03 K( X" d( w: X; p/ E2 x& T
  set num-cars-stopped 02 \6 m  m0 d( ^& U, C5 O- f* Y$ J% t5 C
  set grid-x-inc world-width / grid-size-x
, j$ [# n/ N% @3 j  }+ u  m% \  set grid-y-inc world-height / grid-size-y9 `3 y: ^( p, P! g/ M) }8 W( y
% ]2 b% l+ T! b3 `% g- i
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary
" |( x* X, o4 k& U  set acceleration 0.099
1 u/ w" e4 t1 i$ {8 ?end+ U: ^* q* O3 I4 Y' ~: _9 ?+ F
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;; Make the patches have appropriate colors, set up the roads and intersections agentsets,
4 k3 p2 {4 |9 T;; and initialize the traffic lights to one setting+ v- J- I/ w+ A4 k) I- w( R
to setup-patches
: Q, B4 U9 s0 r  ;; initialize the patch-owned variables and color the patches to a base-color3 N  x% P* r8 i# f7 B& ]
  ask patches
! M3 G$ c& m+ A2 o$ _  [
. [2 T& X/ K& c; X6 c    set intersection? false
3 z7 O0 X9 A! K, y0 T    set auto? false
8 D8 |; N. T$ W* w    set green-light-up? true
8 y: Y4 C' Z: e. k$ S5 R# ]* S: j    set my-row -1  c' m* ?1 l' W) b
    set my-column -1
0 J6 N2 }' z  O    set my-phase -1
8 ^9 a3 [6 l0 ~  W. U; j5 p    set pcolor brown + 3
  v( C- |# [4 K/ _, O* x  ]
# R# U! }' E7 `6 l, F% f
$ E. R: v  j# L4 s5 G( o0 y6 v+ H+ w. w  ;; initialize the global variables that hold patch agentsets
% P+ p, [5 ?( Y  set roads patches with6 i) c3 r: d1 A8 N& \
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or7 o+ E# U) ]6 F) v6 R
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
8 O' V# a/ F: Q9 k. s  set intersections roads with; e4 j5 E7 S! x
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and2 K6 b+ X) [3 v% V4 T+ X: U. n: U
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
6 w; I' [- R2 n& a) V8 Q& w% L& z/ A& E7 G. D! e
  ask roads [ set pcolor white ]
+ f0 c3 H! D1 I" z5 B9 a    setup-intersections
3 E5 @' U8 @; z" R# Fend! f/ ^7 f* d1 T* A8 H" l
其中定义道路的句子,如下所示,是什么意思啊?0 s4 f" D  |3 \6 F
set roads patches with4 F/ d1 c- R# R' Y+ g; B
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
7 ?5 }/ |, {7 H# G6 }+ {    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
2 f( G4 w7 |+ K: Z& x# 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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