r Remove parts of column name after certain characters

Question

I have a large data set with thousands of columns. The column names include various unwanted characters as follows:

col1_3x_xxx
col2_3y_xyz
col3_3z_zyx

I would like to remove all character strings starting with "_3" from all column names to be left with clean:

col1
col2
col3

What is the most efficient way to do this for 5000+ columns?

Answer 1

We can use sub

sub("_3.*", "", df1[,1])
#[1] "col1" "col2" "col3"