Install and load multiple R packages at once

ipak.R

# ipak function: install and load multiple R packages.
# check to see if packages are installed. Install them if they are not, then load them into the R session.

ipak <- function(pkg){
    new.pkg <- pkg[!(pkg %in% installed.packages()[, "Package"])]
    if (length(new.pkg)) 
        install.packages(new.pkg, dependencies = TRUE)
    sapply(pkg, require, character.only = TRUE)
}

# usage
packages <- c("plyr", "reshape2", "RColorBrewer", "scales", "grid","limma","edgeR","DESeq2","gplots","ggplot2","pheatmap","tidyr","sva","tibble","matrixStats","viridis", "statmod", "dendsort","clusterProfiler", "DOSE","GeneOverlap", "VennDiagram","systemPipeR","org.Hs.eg.db","gage", "gageData","pathview","devtools","AnnotationDbi")
ipak(packages)

# if not working then use 
biocLite(c("DESeq2","edgeR","limma","sva","DOSE","devtools","AnnotationDbi","systemPipeR","org.Hs.eg.db","gage", "gageData","pathview","clusterProfiler"))

Just added some more for my need