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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+ I) U% N& M
netlogo自带的social science--traffic grid这一例子当中,+ Z% Y: w5 r$ v3 s( S
globals
3 p, S: R5 N5 [9 |  c[
1 `$ h; a, }% P2 [* G& U  grid-x-inc               ;; the amount of patches in between two roads in the x direction  _, J2 k. k' Y2 ]+ y$ W' H
  grid-y-inc               ;; the amount of patches in between two roads in the y direction" {( S8 `+ k4 F
  acceleration             ;; the constant that controls how much a car speeds up or slows down by if
; d$ r$ Q' ]2 i; q% G7 Z                           ;; it is to accelerate or decelerate4 x7 P/ Z" @+ L
  phase                    ;; keeps track of the phase
1 M: p% L7 V: ?0 [5 l9 k7 ?  num-cars-stopped         ;; the number of cars that are stopped during a single pass thru the go procedure: I9 M  W6 g+ v. x5 l2 B
  current-light            ;; the currently selected light
  h# u: D8 ?) U2 K- g4 P5 \3 ?' W
, \  }: i2 m' v. t; P7 S  p& p; r* a  ;; patch agentsets
4 L6 @- F. d0 }0 K4 a  intersections ;; agentset containing the patches that are intersections/ U" t; V4 @' [6 _0 b( M
  roads         ;; agentset containing the patches that are roads3 b" W$ W- ?0 n5 D) c( ?* ]& K3 H
]  `5 N7 J: f1 ^1 F, W
4 P) Y9 P9 L$ ~# `4 F; Z; p: t) x
turtles-own' R9 |0 _6 j: t8 x' Y) g# m2 @
[
  e* ]- c) u) R  speed     ;; the speed of the turtle
, ~$ F" u. [- y# g  up-car?   ;; true if the turtle moves downwards and false if it moves to the right
" x! f- T' q  ^8 ?# A: c  wait-time ;; the amount of time since the last time a turtle has moved. ~/ C6 a4 g) Y6 i
]: }& D/ v9 L9 m1 t# I

: |7 D3 y& D- E' l7 r: Lpatches-own( Z& A" V; A3 K
[  u4 ~* S& K& \- [9 Z6 _% C
  intersection?   ;; true if the patch is at the intersection of two roads
- e* I. k+ F$ ], B6 w  green-light-up? ;; true if the green light is above the intersection.  otherwise, false.
6 d9 G5 K* \# a8 k. x1 r, D: {7 a  X                  ;; false for a non-intersection patches.  S2 S, Q  M1 b5 x" B
  my-row          ;; the row of the intersection counting from the upper left corner of the
. o8 ^' ~% n$ G6 U- l8 B                  ;; world.  -1 for non-intersection patches.
+ \2 \% ]: D, \; {9 r9 Y  my-column       ;; the column of the intersection counting from the upper left corner of the
4 l# G; m# E% m7 ^: q4 L                  ;; world.  -1 for non-intersection patches.: ~7 t0 s+ W" w
  my-phase        ;; the phase for the intersection.  -1 for non-intersection patches.7 w7 x6 y. L) f3 }0 T  E
  auto?           ;; whether or not this intersection will switch automatically.1 W) C" \, x, _/ K" l" S9 X
                  ;; false for non-intersection patches.7 e! n3 P2 t" u7 z; q5 G  }) i+ q
]
' G$ ?/ ^# C0 ]7 V3 ^9 ?0 p9 q$ J

* a6 D  ^2 c+ L- d$ W9 F;;;;;;;;;;;;;;;;;;;;;;$ j6 }3 W9 K' l/ _/ Y* N
;; Setup Procedures ;;
2 ]0 A, S1 n! r! B& T& V- D;;;;;;;;;;;;;;;;;;;;;;
: _9 x8 j3 l4 [! g
1 N/ G9 B+ S3 B4 P& e;; Initialize the display by giving the global and patch variables initial values.
3 V* q* K( h. }) a, q& a;; Create num-cars of turtles if there are enough road patches for one turtle to
& Y# m" X% l4 S* j;; be created per road patch. Set up the plots.
) E6 F# F/ e3 [  r- |( }to setup2 \% ~6 W! H- f( ]
  ca) N# y6 b  c: z+ v: P/ v
  setup-globals
+ Z7 J1 h2 w4 Q: G8 J: K* }' V$ q# h0 k
  ;; First we ask the patches to draw themselves and set up a few variables
7 Y2 i/ C' E0 T7 e& [' x/ p  setup-patches
1 J$ K& ?" I$ m  make-current one-of intersections! U3 {- W. @7 M' X6 a+ G
  label-current
* B1 v9 a1 G/ u: d* P  z) B1 L' I- o) h9 y, Q! d
  set-default-shape turtles "car"
8 p/ S' Q0 v* Z& {, [" L3 \) E. R
, R' X0 A1 ?  }2 O3 v' j  if (num-cars > count roads)
6 e3 U6 P, R9 q  [  e3 r& _8 }4 _. \9 j1 ~, t
    user-message (word "There are too many cars for the amount of "8 l7 W" g) `/ A4 S
                       "road.  Either increase the amount of roads "
. D6 _# I: ?6 p7 y$ }                       "by increasing the GRID-SIZE-X or "
' b" t7 l- `6 c$ J                       "GRID-SIZE-Y sliders, or decrease the "
- l+ U/ ~6 F5 J6 ^9 \. d, `                       "number of cars by lowering the NUMBER slider.\n"
8 \7 P+ L0 q0 Y7 S$ L" k5 v                       "The setup has stopped.")
9 F4 b0 U: q, v0 d: q# [    stop+ ?- ]# o+ \) G8 c3 B: Z
  ]
- ], n  C+ ^+ n. Z  d- n* T( n- ]6 A. M7 N% |, d; H
  ;; Now create the turtles and have each created turtle call the functions setup-cars and set-car-color
% `' E" p. s, X4 n* l" D: F! z7 k  crt num-cars
$ |4 [$ ^( z, o! Q; z- |9 w, _  [
/ X( M# j+ u# e" x+ X9 G    setup-cars+ V! _+ ?9 w6 f) v* x
    set-car-color$ W# |9 p, u  f6 P
    record-data
9 R# J9 d+ ^& i! Y6 P; Q  ]7 p% e" y: t0 ^! j
" E. Q4 o4 J1 k6 x, D- y% w
  ;; give the turtles an initial speed  \# `( r; k! V& S1 q) I% a2 `
  ask turtles [ set-car-speed ]4 e7 c. H, ~7 ~8 U6 R
" O, J- I( @* n3 h2 {
  reset-ticks
4 Y/ _, p) t3 D/ H( tend8 J8 g5 ?2 H4 T6 t

7 Q! H3 a8 s- p( y# w% ?1 w;; Initialize the global variables to appropriate values
4 W& o& k" P8 p* [* H/ j3 T# N/ kto setup-globals
7 k( v5 [+ t$ h1 q! `1 m  set current-light nobody ;; just for now, since there are no lights yet
% S: ^0 ?' S1 m+ \+ M! C7 [( q  set phase 0, N  }7 c& g  o1 w( h. E! t
  set num-cars-stopped 0! C: E( p4 _" Q
  set grid-x-inc world-width / grid-size-x
: N2 N) F  S+ ^5 \  set grid-y-inc world-height / grid-size-y4 T) k; ^: w) e1 f  s
, S) G' c' t$ P% ~' v  [
  ;; don't make acceleration 0.1 since we could get a rounding error and end up on a patch boundary  X4 ?! S5 ^& X& R
  set acceleration 0.099
. h" P* x: J/ u! s+ J( U) W2 U, Xend- ~' V" y- ~3 r4 \9 C
, W: ]( E/ {; @( s! ~' j
;; Make the patches have appropriate colors, set up the roads and intersections agentsets,/ x- c5 q( z1 K: G
;; and initialize the traffic lights to one setting3 b" X/ b' Q' d: J/ x2 T
to setup-patches: }8 N1 \. V2 A4 y
  ;; initialize the patch-owned variables and color the patches to a base-color
& d1 C" h  s- A  K8 Y  ask patches
( a, Q( |4 f* b+ P7 P/ @* I  [! g$ J5 ~/ W; H. K
    set intersection? false
8 H3 N: F# T4 ^    set auto? false8 k6 x% V* Q/ g/ H
    set green-light-up? true
- X- S) I: H+ I! J. g, V    set my-row -16 w2 y; Z2 @2 ~! F
    set my-column -1) k* z2 \  q0 e5 b) T
    set my-phase -1
' h2 y& @- p3 k6 d: N$ E) Z    set pcolor brown + 3+ F1 C' y8 H3 `* Q( i) B
  ]
# U5 ]! b) w4 q$ K& ^3 v* e  f8 f3 R* i! w# W6 S4 S
  ;; initialize the global variables that hold patch agentsets6 B" @6 I( H- Y3 R4 l, K5 z+ H
  set roads patches with7 p  m8 S; Y  S* M0 \- o% k  f
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or6 m3 n! `9 }; D1 h3 C
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]- ^% v( q. b/ o
  set intersections roads with4 L& k$ w8 ?$ E: h3 r: C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) and. N/ O' I0 P* m" R: q
    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
& R6 p, t1 E- d# e- o$ c' R- ?1 j3 h2 Z
  ask roads [ set pcolor white ]
9 h5 T5 A6 r2 O- [0 l8 b4 ~    setup-intersections
2 z+ U' F1 x9 Aend
, i' f  N9 A+ r1 I6 ]- Z  t其中定义道路的句子,如下所示,是什么意思啊?3 K& r/ N7 H" R5 `. v! V
set roads patches with+ z' m4 n; @8 T8 c- C
    [(floor((pxcor + max-pxcor - floor(grid-x-inc - 1)) mod grid-x-inc) = 0) or
1 v& K" g3 j! J0 \: r0 J    (floor((pycor + max-pycor) mod grid-y-inc) = 0)]
5 x4 y( `2 b" \( K) W( p1 O( X- D, V: h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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