ellipsoidhull(cluster)
ellipsoidhull()所属R语言包：cluster
Compute the Ellipsoid Hull or Spanning Ellipsoid of a Point Set
计算椭球赫尔点集或跨椭球
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Compute the “ellipsoid hull” or “spanning ellipsoid”, i.e. the ellipsoid of minimal volume ("area" in 2D) such that all given points lie just inside or on the boundary of the ellipsoid.
计算“椭球船体”或“跨越椭球”，即最小体积椭球（“区域”2D）等，躺在里面或椭球边界上的所有点。
用法----------Usage----------
ellipsoidhull(x, tol=0.01, maxit=5000,
ret.wt = FALSE, ret.sqdist = FALSE, ret.pr = FALSE)
## S3 method for class 'ellipsoid'
print(x, digits = max(1, getOption("digits") - 2), ...)
参数----------Arguments----------
参数：x
the n p-dimensional points asnumeric n x p matrix.
np三维点asnumericn x p矩阵。
参数：tol
convergence tolerance for Titterington's algorithm. Setting this to much smaller values may drastically increase the number of iterations needed, and you may want to increas maxit as well.
Titterington的算法的收敛公差。设置此要小得多值可能大幅增加的需要迭代，你可能想increasmaxit以及。
参数：maxit
integer giving the maximal number of iteration steps for the algorithm.
整数，算法的最大迭代步数。
参数：ret.wt, ret.sqdist, ret.pr
logicals indicating if additional information should be returned, ret.wt specifying the weights, ret.sqdist the squared distances and ret.pr the final probabilities in the algorithms.
逻辑值表示，如果更多的信息应返回，ret.wt指定的权重，ret.sqdist平方距离ret.pr概率算法的最后的。
参数：digits,...
the usual arguments to print methods.
print方法通常参数。
Details
详情----------Details----------
The “spanning ellipsoid” algorithm is said to stem from Titterington(1976), in Pison et al(1999) who use it for clusplot.default.<br> The problem can be seen as a special case of the “Min.Vol.” ellipsoid of which a more more flexible and general implementation is cov.mve in the MASS package.
“跨越椭球”的算法，据说源于Titterington（1976）皮松等（1999）clusplot.default。参考使用的问题作为一个“特殊情况可以看出， Min.Vol。“椭球，其中更多更灵活的和一般的执行是cov.mveMASS包。
值----------Value----------
an object of class "ellipsoid", basically a list with several components, comprising at least
一个类的对象"ellipsoid"，基本上是list几部分组成，包括至少
参数：cov
p x p covariance matrix description the ellipsoid.
p x p协方差矩阵描述椭球。
参数：loc
p-dimensional location of the ellipsoid center.
p立体椭球中心的位置。
参数：d2
average squared radius. Further, d2 = t^2, where t is “the value of a t-statistic on the ellipse boundary” (from ellipse in the ellipse package), and hence, more usefully, d2 = qchisq(alpha, df = p), where alpha is the confidence level for p-variate normally distributed data with location and covariance loc and cov to lie inside the ellipsoid.
平均平方半径。此外，d2 = t^2，其中t是“椭圆边界值的t-统计”（从ellipse在的ellipse包），因此，用，d2 = qchisq(alpha, df = p)，其中alphaP-变量正态分布的位置和协loc和cov位于椭球内的数据的置信水平。
参数：wt
the vector of weights iff ret.wt was true.
权重向量，当且仅当ret.wt是真实的。
参数：sqdist
the vector of squared distances iff ret.sqdist was true.
IFF平方距离向量ret.sqdist是真实的。
参数：prob
the vector of algorithm probabilities iff ret.pr was true.
敌我识别算法的概率向量ret.pr是真实的。
参数：it
number of iterations used.
使用迭代数。
参数：tol, maxit
just the input argument, see above.
只是输入参数，见上面。
参数：eps
the achieved tolerance which is the maximal squared radius minus p.
实现宽容是最大的平方半径减去p。
参数：ierr
error code as from the algorithm; 0 means ok.
算法;0是指确定的错误代码。
参数：conv
logical indicating if the converged. This is defined as it < maxit && ierr == 0.
如果融合的逻辑表示。这被定义为it < maxit && ierr == 0。
作者（S）----------Author(s)----------
Martin Maechler did the present class implementation; Rousseeuw
et al did the underlying code.
参考文献----------References----------
Displaying a Clustering with CLUSPLOT, Computational Statistics and Data Analysis, 30, 381–392.<br> A version of this is available as technical report from http://www.agoras.ua.ac.be/abstract/Disclu99.htm
Algorithms for computing D-optimal design on finite design spaces. In Proc.\ of the 1976 Conf.\ on Information Science and Systems, 213–216; John Hopkins University.
参见----------See Also----------
predict.ellipsoid which is also the predict method for ellipsoid objects. volume.ellipsoid for an example of "manual" ellipsoid object construction;<br> further ellipse from package ellipse and ellipsePoints from package sfsmisc.
predict.ellipsoid这也是predictellipsoid对象的方法。 volume.ellipsoid手册ellipsoid对象建设的例子;参考进一步ellipseellipse和ellipsePoints包包sfsmisc 。
chull for the convex hull, clusplot which makes use of this; cov.mve.
chull凸壳，clusplot这使得使用本;cov.mve。
举例----------Examples----------
x <- rnorm(100)
xy <- unname(cbind(x, rnorm(100) + 2*x + 10))
exy <- ellipsoidhull(xy)
exy # >> calling print.ellipsoid()[>>致电print.ellipsoid（）]
plot(xy)
lines(predict(exy))
points(rbind(exy$loc), col = "red", cex = 3, pch = 13)
exy <- ellipsoidhull(xy, tol = 1e-7, ret.wt = TRUE, ret.sq = TRUE)
str(exy) # had small `tol', hence many iterations[有小TOL“，因此多次迭代]
(ii <- which(zapsmall(exy $ wt) > 1e-6)) # only about 4 to 6 points[只有约4至6点]
round(exy$wt[ii],3); sum(exy$wt[ii]) # sum to 1[等于1]
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
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发表于 2012-2-16 22:06:24
