Unique rows with multiple comma separated entries in R [duplicate]

Answer 1

First set up the test data. Note that we have made the columns to be of "character" class rather than "factor" by using as.is=TRUE :

Lines <- "SNP   hu_mRNA     gene
 chr1.111642529 NM_002107    H3F3A
 chr1.111642529 NM_005324    H3F3B
 chr1.111801684 BC098118     
 chr1.111925084 NM_020435    GJC2
  chr1.11801605 AK027740     
  chr1.11801605 NM_032849    C13orf33
 chr1.151220354 NM_018913    PCDHGA10
 chr1.151220354 NM_018918    PCDHGA5"
cat(Lines, "\n", file = "data.txt")
DF <- read.table("data.txt", header = TRUE, na.strings = "", as.is = TRUE)

Now try this aggregate statement:

> aggregate(. ~ SNP, DF, toString)
             SNP              hu_mRNA              gene
1 chr1.111642529 NM_002107, NM_005324      H3F3A, H3F3B
2 chr1.111925084            NM_020435              GJC2
3  chr1.11801605            NM_032849          C13orf33
4 chr1.151220354 NM_018913, NM_018918 PCDHGA10, PCDHGA5