AggregateSVD(GeneSelector)
AggregateSVD()所属R语言包：GeneSelector
Agregation of repeated rankings using the singular value decomposition (SVD)
使用重复排名agregation的奇异值分解（SVD）
译者：生物统计家园网 机器人LoveR
描述----------Description----------
A matrix storing all rankings is centered rowwise (=genewise), and then approximated using only the first singular value and the first singular vectors (s. Golub and Van Loan (1983) for details about the SVD). The rowwise mean vector is added afterwards, and the rowwise mean are finally used as aggregation. A weighting scheme giving more weight to top genes is incorporated by an (iteratively) weighted SVD, which is re-computed until convergence. Note that the SVD is closely related to principal component analysis, a standard tool for dimension reduction in high-dimensional datasets.
矩阵存储所有排名居中rowwise（= 2-6。），然后使用只有第一奇异值和奇异向量的第一（S.戈卢布和Van贷款（1983年）有关的SVD的详细信息）近似。添加rowwise平均向量之后，终于rowwise平均聚合使用。加权计划，使更多的重量，顶部基因被纳入（反复）加权SVD的，这是重新计算，直到收敛。注意的SVD是密切相关的主成分分析，为减少维在高维数据集的标准工具。
用法----------Usage----------
AggregateSVD(RR, weightscheme = c("original", "iterative"), decay = c("linear", "quadratic", "exponential"), alpha=1)
参数----------Arguments----------
参数：RR
An object of class RepeatedRanking
一个对象的类RepeatedRanking
参数：weightscheme
If weightscheme = "original", the weights are computed according to the reference ranking RR@ranking@original. If weightscheme = "iterative", the weights are intially set to 1 for all genes. After the computation of the SVD and in turn the first aggregation, the weightes are updated according to that aggregation. This process is repeated until convergence.
如果weightscheme = "original"，权重计算根据参考排名RR@ranking@original。如果weightscheme = "iterative"，重量intially设置为所有基因1。的SVD计算后，在打开的第一聚集，weightes更新，聚集。重复这个过程直到收敛。
参数：decay
Argument controlling the weight decay of the weights of the summands contributing to the stability measure. If decay=linear, then we have weight 1/r for rank r, if decay=quadratic, then the weight is 1/r^2 and if decay=quadratic, then the weight is exp(-alpha*r) where alpha is a tuning parameter, specified via the argument alpha.
控制参数的稳定措施的加数的权重衰变。如果decay=linear，然后我们重1/r级r如果decay=quadratic，然后重1/r^2如果decay=quadratic，然后重量是exp(-alpha*r)alpha是一个调整参数，通过参数alpha指定。
参数：alpha
s. decay.
第decay。
值----------Value----------
An object of class AggregatedRanking.
对象类AggregatedRanking。
作者（S）----------Author(s)----------
Martin Slawski <br>
Anne-Laure Boulesteix
参考文献----------References----------
<h3>See Also</h3>
举例----------Examples----------
## Load toy gene expression data[＃加载玩具基因表达数据]
data(toydata)
### class labels[＃＃类的标签]
yy <- toydata[1,]
### gene expression[＃＃基因表达]
xx <- toydata[-1,]
### run RankingTstat[＃运行RankingTstat的]
ordT <- RankingTstat(xx, yy, type="unpaired")
### Generate Leave-one-out Foldmatrix[＃生成留出Foldmatrix]
loo <- GenerateFoldMatrix(y = yy, k=1)
### Get all rankings[＃获取所有排名]
loor_ordT <- RepeatRanking(ordT, loo)
### aggregate rankings[＃总排名]
agg_svd_ordT <- AggregateSVD(loor_ordT, weightscheme = "iterative", decay = "linear")
toplist(agg_svd_ordT)
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。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-2-25 19:01:28
