微生物组数据的centered log-ratio transformation 在分析肠道微生物数据中,一般会对数据进行一定的转换,以使数据尽可能的服从正态分布。常用的方法有Centered Log-ratio (CLR)transformation和Cumulative Sum Scale (CSS)transformation等。这里介绍一下在R中如何进行CLR转换。 CLR转换的公式如下: clr.png g(x)是x...
中心对数比变换(Centered Log-Ratio Transformation,简称CLR)和普通的对数比变换(Log-Ratio Transformation,简称LR)都是用于处理组成数据(Compositional Data,CoDa)的方法。在组成数据分析中,数据通常表示为比例或百分比,而这些数据的总和通常是固定的(如100%)。这样的数据具有特殊的几何和代数结构,需要特定的统计方法来正...
Faith, M. Centered Log-Ratio (clr) Transformation and Robust Principal Component Analysis of Long-Term NDVI Data Reveal Vegetation Activity Linked to Climate Processes. Climate 2015, 3, 135-149. [CrossRef]Faith, M.K. Centered Log-Ratio (clr) Transformation and Robust Principal Component Analysis...
在分析肠道微生物数据中，一般会对数据进行一定的转换，以使数据尽可能的服从正态分布。常用的方法有 Centered Log-ratio (CLR) transformation和 Cumulative Sum Scale (CSS) transformation等。这里介绍一下在R中如何进行CLR转换。 CLR 转换的公式如下：明白clr的基本原理，在R中的实现相对...
This study uses a centered log-ratio (clr) transformation approach and robust principal component analysis (PCA), on a long-term Normalized Difference Vegetation Index (NDVI) dataset to test its applicability in analyzing large multi-temporal data, and potential to recognize important trends and ...
最近,来自西班牙科学团队的一篇题为“Compositional Data Analysis of Microbiome and Any-Omics Datasets: A Validation of the Additive Logratio Transformation” 的文章指出: ALR对数转换可以有效提供一组简单的变量来表示整个成分数据集,其关键节点在于选择哪个成分为参考,并使用三个高维组学数据集进行验证。
Dilatation is a type of transformation that we can perform on a figure that is assumed to be in the Cartesian plane. Dilatation can be a reduction or an expansion, depending on the scale factor. The dilation is performed through the vertices of the f...
Across these medical records, we measured disease–drug co-occurrence enrichment as the ratio of the odds of using a specific drug for a disease to the odds of using it for other diseases. We derived 619,200 log(odd ratio) (log(OR)) values for every drug–disease pair and applied necess...
In step 1, a catchment area, or geographic boundary, is defined for each resource and a corresponding capacity-to-population ratio is calculated. The geographic unit of analysis moves, or floats, from one resource location to the next, hence the “floating” in the method's name. In the ...
Centered log ratio transformationJames M. Curran