refer to range of columns by name in R

Question

I need help with something that might be fairly simple in R. I want to refer to a range of columns in a data frame (e.g., extracting a few select variables). However, I don\

Answer 1

A column number can be identified from a column name within a data frame as follows:

which(colnames(mydf)=="a")

where mydf is a data frame and a is the name of the column the column number is required for.

(Source)

This can be used to create a column range:

firstcol = which(colnames(x)=="a")
lastcol = which(colnames(x)=="b")

mydf[c(firstcol:lastcol)]