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

I didn't see a simple merge solution, so here is one:

res <- merge(data.frame(col1=1:max(df$col1)),df,by="col1",all.x=TRUE)
res$col2 <- ifelse(is.na(res$col2),0,res$col2)

The second line is replacing the NA's from the merge (left outer join) with zeros. As @Axeman points out, this can also be accomplished by:

res$col2[is.na(res$col2)] <- 0

The result is:

res
##   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