I want to combine two variables into one with a date format

Question

I have a data set with a character column for months (MONTH) and a numeric column indicating years (YEAR). In order to work with it as panel data, I ne

Answer 1

In base R you could do something like:

transform(df,TIME = paste(sprintf('%02d',match(MONTH,toupper(month.abb))),YEAR,sep = '-'))[c(1,5,4)]
       STATE    TIME VALUE
1 California 01-2018   800
2 California 02-2018   780
3 California 03-2018   600
4        ...  NA-...   ...
5   Minesota 01-2018   800
6   Minesota 02-2018   780
7   Minesota 03-2018   600