how do I search for columns with same name, add the column values and replace these columns with same name by their sum? Using R

Question

I have a data frame where some consecutive columns have the same name. I need to search for these, add their values in for each row, drop one column and replace the other wi

Answer 1

Here is my one liner

# transpose data frame, sum by group = rowname, transpose back.
t(rowsum(t(dfrm), group = rownames(t(dfrm))))