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

Here are a couple of base solutions:

as.data.frame.table(tapply(df[[3]], df[2:1], c))

and

merge(df, 
      expand.grid(Position = unique(df$Position), Name = unique(df$Name)), 
      all = TRUE)