How to name column header for first column ?

Question

[Björn]

I have a dataset with a missing column header for first column. How to name it so that I can find it using

a$

I used following command but got error

a$miRNAs<-row.names(a)

Warning message:
In a$miRNAs <- row.names(a) : Coercing LHS to a list

How to find the solution?

[h.mon]

It is not a data frame column, these are the row names:

rownames( a );

You can't assign a name to the row names.

[steve]

If you are trying to access a single column from a dataframe, you should use this syntax instead: a[["column_name"]]. There are methods for renaming columns listed here

Answer 1

[zx8754]

It is rownames not a column. Since you have mentioned dplyr, we can convert it to columns using packages from tidyverse, here is an example:

# example dataset with rownames
a <- mtcars[1:3, 1:3]
a
#                mpg cyl disp
# Mazda RX4     21.0   6  160
# Mazda RX4 Wag 21.0   6  160
# Datsun 710    22.8   4  108

library(dplyr)
library(tibble)

a <- a %>% 
  rownames_to_column(var = "myName")

a
#          myName  mpg cyl disp
# 1     Mazda RX4 21.0   6  160
# 2 Mazda RX4 Wag 21.0   6  160
# 3    Datsun 710 22.8   4  108

Answer 2

[cpad0112]

> test=mtcars[1:3, 1:3]
> test
                        mpg cyl disp
Mazda RX4         Mazda RX4   6  160
Mazda RX4 Wag Mazda RX4 Wag   6  160
Datsun 710       Datsun 710   4  108
> cbind(cars=rownames(test),test)
                       cars  mpg cyl disp
Mazda RX4         Mazda RX4 21.0   6  160
Mazda RX4 Wag Mazda RX4 Wag 21.0   6  160
Datsun 710       Datsun 710 22.8   4  108