stacking/melting multiple columns into multiple columns in R
问题 I am trying to melt/stack/gather multiple specific columns of a dataframe into 2 columns, retaining all the others. I have tried many, many answers on stackoverflow without success (some below). I basically have a situation similar to this post here: Reshaping multiple sets of measurement columns (wide format) into single columns (long format) only many more columns to retain and combine. It is important to mention my year columns are factors and I have many, many more columns than the sample