Aaghaz Hussain Aaghaz Hussain - 21 days ago 5
R Question

Convert row names into first column

I have a data frame like this:

df
VALUE ABS_CALL DETECTION P-VALUE
1007_s_at "957.729231881542" "P" "0.00486279317241156"
1053_at "320.632701283368" "P" "0.0313356324173416"
117_at "429.842323161046" "P" "0.0170004527476119"
121_at "2395.7364289242" "P" "0.0114473584876183"
1255_g_at "116.493632746934" "A" "0.39799368200131"
1294_at "739.927122116896" "A" "0.0668649772942343"


I want to convert the row names into the first column. Currently I use something like this to make row names as the first column:

d <- df
names <- rownames(d)
rownames(d) <- NULL
data <- cbind(names,d)


Is there a single line to do this?

Answer

You can both remove row names and convert them to a column by reference (without reallocating memory using ->) using setDT and its keep.rownames = TRUE argument from the data.table package

library(data.table)
setDT(df, keep.rownames = TRUE)[]
#    rn     VALUE  ABS_CALL DETECTION     P.VALUE
# 1:  1 1007_s_at  957.7292         P 0.004862793
# 2:  2   1053_at  320.6327         P 0.031335632
# 3:  3    117_at  429.8423         P 0.017000453
# 4:  4    121_at 2395.7364         P 0.011447358
# 5:  5 1255_g_at  116.4936         A 0.397993682
# 6:  6   1294_at  739.9271         A 0.066864977