Importing in R; (read.csv) Ignore non-numeric columns automatically -

i want import tsv file including non-numeric fields (i.e., date or string) in r:

num1    num2    date 1   2   2012-10-18 12:17:19 2   4   2014-11-16 09:30:23 4   11  2010-03-18 22:18:04 12  3   2015-02-18 12:55:50 13  1   2014-05-16 10:39:11 2   14  2011-05-26 20:48:54 

i using following command:

a = read.csv("c:\test\testfile.tsv", sep="\t")

i want ignore non-numeric values automatically (or put "na"). , don't want mention string column names ignored.

i tried "stringsasfactors" , "as.is" parameters, no success.

any ideas?

you have quite few options here. first, can inform r while reading table:

data <- read.csv("c:\test\testfile.tsv",  sep="\t",  colclasses=c(na, na, "null")) 

if have many nonnumeric columns, 10, can use rep colclasses=c(na, na, rep("null", 10)).

second, can read , process deletion afterwards (note stringsasfactors):

data <- read.csv("c:\test\testfile.tsv",      sep="\t", stringsasfactors = false) 

you can subset column identified character.

df[, !sapply(df, is.character)] 

or apply destructive method data.frame:

  df[sapply(df, is.character)] <- list(null) 

you can go further make sure numeric columns left:

df[,-grep ("date|factor|character", sapply(df, class))] <- list(null)