R: Adding NAs into Data Frame

Question

I have a data frame like so:

Name   Position   Value
a         1        0.2
a         3        0.4
a         4        0.3
b         1        0.5
b         2          


        

Answer 1

I would use data.table but in a different way that @akrun underlined:

library(data.table)
dt = as.data.table(df)
setkey(dt, Name, Position)
dt[CJ(unique(Name),unique(Position))]