I have a .txt file that contains row names. However, R set the row names as the first column.
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2 Answers
If you used read.table() (or one of it's ilk, e.g. read.csv()) then the easy fix is to change the call to:
read.table(file = "foo.txt", row.names = 1, ....)
where .... are the other arguments you needed/used. The row.names argument takes the column number of the data file from which to take the row names. It need not be the first column. See ?read.table for details/info.
If you already have the data in R and can't be bothered to re-read it, or it came from another route, just set the rownames attribute and remove the first variable from the object (assuming obj is your object)
rownames(obj) <- obj[, 1] ## set rownames
obj <- obj[, -1] ## remove the first variable
3 Comments
mpag
You could also use column-based slicing (at least for matrix and dataframe).
rownames(obj) <- t(obj[1]) ##get row names from first column obj <- obj[-1] ## remove first column
Code42
So, the integer for row.names is 1-indexed? The first column isn't called Column 0?
Gavin Simpson
@Dr_Hope All vectors at the R level are 1-indexed, hence the first row is row 1 and the first column is column 1.
See ?read.table. Basically, when you use read.table, you specify a number indicating the column:
##Row names in the first column
read.table(filname.txt, row.names=1)
