Question

In my code, I am filling the columns of a dataframe with vectors, as so:

df1[columnNum] <- barWidth

This works fine, except for one thing: I want the name of the vector variable (barWidth above) to be retained as the column header, one column at a time. Furthermore, I do not wish to use cbind. This slows the execution of my code down considerably. Consequently, I am using a pre-allocated dataframe.

Can this be done in the vector-to-column assignment? If not, then how do I change it after the fact? I can’t find the right syntax to do this with colNames().

TIA

Answer 1

If you have the list of names of vectors you want to apply you could do:

namevec <- c(...,"barWidth"...,)
columnNums <- c(...,10,...)

df1[columnNums[i]] <- get(namevec[i])
names(df1)[columnNums[i]] <- namevec[i]

or even

columnNums <- c(barWidth=4,...)
for (i in seq_along(columnNums)) {
   df1[columnNums[i]] <- get(names(columnNums)[i])
}
names(df1)[columnNums] <- names(columnNums)

but the deeper question would be where this set of vectors is coming from in the first place: could you have them in a list all along?