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
         


        

Answer 1

We can try the str_extract with regular expression pattern "^[^_]+(?=_)":

stringr::str_extract(c("col1_3x_xxx", "col2_3y_xyz", "col3_3z_zyx"), "^[^_]+(?=_)")
[1] "col1" "col2" "col3"

where in the pattern:

The first ^ matches the beginning of the string; [^_]+ matches one or more non _ character, ^_ means any character but _. (?=...) stands for lookahead, so we are looking for pattern ahead of _.