Extending Suffixes in Merge to All Non-by Columns

Question

suffixes in merge works only on common column names. Is there anyway to extend this to the rest of the columns as well without manually updating co

Answer 1

This is an interesting question, and I doubt that extending merge would be a straightforward solution unless Matt Dowle and Co. think it's something worth implementing in merge.data.table.

Here's one approach that came to mind:

DTs <- c("df1", "df2")
suffixes <- seq_along(DTs)

for (i in seq_along(DTs)) {
  Name <- setdiff(colnames(get(DTs[i])), "a")
  setnames(get(DTs[i]), Name, paste(Name, suffixes[i], sep = "."))
}

merge(df1, df2, by = "a") # Will obviously work as you expect now