Compute the distance-to-median statistic

Description

Compute the distance-to-median statistic for the CV2 residuals of all genes

Usage

DM(mean, cv2, win.size=50)

Arguments

Details

This function will compute the distance-to-median (DM) statistic described by Kolodziejczyk et al. (2015). Briefly, a median-based trend is fitted to the log-transformed cv2 against the log-transformed mean. The DM is defined as the residual from the trend for each gene. This statistic is a measure of the relative variability of each gene, after accounting for the empirical mean-variance relationship. Highly variable genes can then be identified as those with high DM values.

Value

A numeric vector of DM statistics for all genes.

Author(s)

Jong Kyoung Kim, with modifications by Aaron Lun

References

Kolodziejczyk AA, Kim JK, Tsang JCH et al. (2015). Single cell RNA-sequencing of pluripotent states unlocks modular transcriptional variation. Cell Stem Cell 17(4), 471–85.

Examples

ngenes <- 10000
means <- exp(runif(ngenes, 2, 8))
cv2 <- rgamma(ngenes, 5, 5)
dm.stat <- DM(means, cv2)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
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Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(scran)
Loading required package: BiocParallel
Loading required package: scater
Loading required package: Biobase
Loading required package: BiocGenerics
Loading required package: parallel

Attaching package: 'BiocGenerics'

The following objects are masked from 'package:parallel':

    clusterApply, clusterApplyLB, clusterCall, clusterEvalQ,
    clusterExport, clusterMap, parApply, parCapply, parLapply,
    parLapplyLB, parRapply, parSapply, parSapplyLB

The following objects are masked from 'package:stats':

    IQR, mad, xtabs

The following objects are masked from 'package:base':

    Filter, Find, Map, Position, Reduce, anyDuplicated, append,
    as.data.frame, cbind, colnames, do.call, duplicated, eval, evalq,
    get, grep, grepl, intersect, is.unsorted, lapply, lengths, mapply,
    match, mget, order, paste, pmax, pmax.int, pmin, pmin.int, rank,
    rbind, rownames, sapply, setdiff, sort, table, tapply, union,
    unique, unsplit

Welcome to Bioconductor

    Vignettes contain introductory material; view with
    'browseVignettes()'. To cite Bioconductor, see
    'citation("Biobase")', and for packages 'citation("pkgname")'.

Loading required package: ggplot2

Attaching package: 'scater'

The following object is masked from 'package:stats':

    filter

> png(filename="/home/ddbj/snapshot/RGM3/R_BC/result/scran/DM.Rd_%03d_medium.png", width=480, height=480)
> ### Name: Distance-to-median
> ### Title: Compute the distance-to-median statistic
> ### Aliases: DM
> ### Keywords: variance
> 
> ### ** Examples
> 
> ngenes <- 10000
> means <- exp(runif(ngenes, 2, 8))
> cv2 <- rgamma(ngenes, 5, 5)
> dm.stat <- DM(means, cv2)
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>