R add row when value is missing

Question

I'm having some trouble in editing my data frame. First, my data:

X1 0.7
X2 0.05
X3 0.4
X5 0.9

What I want to do is add a row X4 with 0, so that my data looks like:

X1 0.7
X2 0.05
X3 0.4
X4 0
X5 0.9

I have a large data set, and the missing values are at random places. How do I find the missing values in R to add a row?

akrun · Accepted Answer · 2016-03-08 12:12:28Z

6

We can use merge with all.x=TRUE. Based on the example provided in the OP's post, we extract the numeric part from the first column using sub, convert to numeric, get the sequence on the range of values and paste with 'X' to create a new 'data.frame'. This will be merged with the old dataset, so that wherever there is no matching values for the first column in the old dataset, the corresponding elements in the second column will be filled by NA. If needed, we can change those to 0 using is.na (but not recommended).

dM <- merge(data.frame(V1=paste0("X", Reduce(`:`, 
   range(as.numeric(sub('\\D+', '', df1$V1)))))), df1, all.x=TRUE)
dM$V2[is.na(dM$V2)] <- 0
dM
#  V1   V2
#1 X1 0.70
#2 X2 0.05
#3 X3 0.40
#4 X4 0.00
#5 X5 0.90

edited Mar 8, 2016 at 12:12

answered Mar 8, 2016 at 11:53

akrun

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