merge list elements which are different dimensions r [duplicate]

Answer 1

We can do this with dcast from data.table which can take multiple value.var columns

library(data.table)
dcast(setDT(df), Area ~ year, value.var = c("P", "N"))
#  Area P_2017 P_2018 N_2017 N_2018
#1:    1      5      1      5      1
#2:    2      6      2      6      2
#3:    3      7      3      7      3
#4:    4     NA      4     NA      4