corr_metric {MetProc}

Calculate Correlation of Missing Rates between Pooled Plasma and Biological Samples

Description

Calculates the correlation of missing rates between the two flanking pooled plasma samples and intervening biological samples for each block in the injection order. A block is defined as a set of biological samples and their flanking pooled plasma samples. See sampledata for an example of the data format and block structure. Requires 2 arguments as input: 1. The metabolomics dataset formatted from the read.met function and 2. A list of 2 elements output from the get_group function containing column indices of pooled plasma samples and biological samples, respectively. If either pooled plasma or biological samples are entirely absent or entirely present, the function will return NA for the metric of that metabolite as the standard deviation of a vector will be 0.

Usage

corr_metric(df, grps)

Arguments

df

The metabolomics dataset, ideally read from the read.met function. Each column represents a sample and each row represents a metabolite. Columns should be labeled with some unique prefix denoting whether the column is from a biological sample or pooled plasma sample. For example, all pooled plasma samples may have columns identified by the prefix “PPP” and all biological samples may have columns identified by the prefix “X”. Missing data must be coded as NA. Columns must be ordered by injection order.

grps

A list of 2 elements from the get_group function. Element "pp" should contain indices of pooled plasma columns and "sid" should contain indicies of biological sample columns.

Value

Returns a vector of equal length to the number of rows in df (representing metabolites) with the correlation of missing rates between flanking pooled plasma and intervening biological samples across all blocks.

See Also

See MetProc-package for examples of running the full process.

Examples

library(MetProc)
#Read metabolomics data
metdata <- read.met(system.file("extdata/sampledata.csv", package="MetProc"),
headrow=3, metidcol=1, fvalue=8, sep=",", ppkey="PPP", ippkey="BPP")

#Get indices of samples and pooled plasma
grps <- get_group(metdata,'PPP','X') 

#get correlation metrics of metabolites
corrs <- corr_metric(metdata,grps)