Replace missing values with a value from another column

Question

If I have:

s <- data.frame(ID=c(191, 282, 202, 210), Group=c("", "A", "", "B"), stringsAsFactors=FALSE)
s
   ID Group
1 191      
2 282     A
3 202      
4 210     B

I can replace the empty cells with N like this:

ds$Group[ds$Group==""]<-"N"

s
   ID Group
1 191     N 
2 282     A
3 202     N
4 210     B

But I would need to replace the empty cells with a value from another column. How can I accomplish this?:

s
   ID Group Group2
1 191     D      D
2 282     A      G
3 202     G      G
4 210     B      D

Relevant post: stackoverflow.com/questions/19253820 ds$Group <- coalesce2(ds$Group, ds$Group2) — zx8754
– zx8754, Commented Mar 22, 2016 at 10:26

akrun · Accepted Answer · 2016-03-22 11:14:32Z

6

We can use data.table to assign the values in "Group2" to "Group" where the "Group" is "" specified in the "i" condition.

library(data.table)
setDT(s)[Group=="", Group:= Group2]

As the assignment happens in place, it is considered to be efficient.

edited Mar 22, 2016 at 11:14

answered Mar 22, 2016 at 11:13

akrun

891k38 gold badges590 silver badges700 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

radiumhead · Accepted Answer · 2016-03-22 10:21:17Z

4

ifelse(test, yes, no) is a handy function to do just that, and it can be used on vectors. Using your last data.frame:

s <- data.frame(ID = c(191, 282, 202, 210),
    Group = c("", "A", "", "B"),
    Group2 = c("D", "G", "G", "D"))

s$Group <- ifelse(test = s$Group != "", yes = s$Group, no = s$Group2)

The first argument is the test. For each value in the vector, if the test is true, then it will take the value in yes, otherwise it will take the value in no.

answered Mar 22, 2016 at 10:21

radiumhead

5022 silver badges9 bronze badges

Collectives™ on Stack Overflow

Replace missing values with a value from another column

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related