Extend an irregular sequence and add zeros to missing values

Question

I have a data frame with a sequence in \'col1\' and values in \'col2\':

col1 col2
2     0.02
5     0.12
9     0.91
13    1.13

I want to exp

Answer 1

Just to add a different point of view, consider that what you have can be seen as a sparse vector, i.e. a vector whose only the non-zero values are defined. Sparse vectors are implemented by the Matrix package in R. If df is your initial data.frame, try:

require(Matrix)
data.frame(col1=seq_len(max(df$col1)),
      col2=as.vector(sparseVector(df$col2,df$col1,max(df$col1))))
#   col1 col2
#1     1 0.00
#2     2 0.02
#3     3 0.00
#4     4 0.00
#5     5 0.12
#6     6 0.00
#7     7 0.00
#8     8 0.00
#9     9 0.91
#10   10 0.00
#11   11 0.00
#12   12 0.00
#13   13 1.13

The same result in a one-liner base R:

data.frame(col1=seq_len(max(df$col1)),
   col2=`[<-`(numeric(max(df$col1)),df$col1,df$col2))