R: Combining columns under precondition

Question

I want to have a column's values equal another column's values if the first column's value is NA in this row. So I want to change something like this

A  B
3  NA
NA NA
NA NA
5  NA
NA NA
NA NA
7  5

to something like this

A  B
3  3
NA NA
NA NA
5  5
NA NA
NA NA
7  5

I am fairly new to R and any other kind of programming.

suppose your data is in a `data.frame` called `dat`: `ifelse(is.na(dat$B), dat$A, dat$B)` — bouncyball, Jul 15 '18 at 13:20
Have a look at `dplyr::coalesce()`. It will make problem simpler. — MKR, Jul 15 '18 at 13:22
Possible duplicate of [Combine column to remove NA's](https://stackoverflow.com/questions/14563531/combine-column-to-remove-nas) — MKR, Jul 15 '18 at 13:59

score 0 · Answer 1 · answered Jul 15 '18 at 14:00

0

try:

df$B[is.na(df$B)] <- df$A

answered Jul 15 '18 at 14:00

Zahiro Mor

score 0 · Accepted Answer · answered Jul 15 '18 at 14:10

As per OP's description:

equal another column's values if the first column's value is NA in this row

Could you please try following and let me know if this helps you.

df21223$B[is.na(df21223$B[1])] <- df21223$A

Output will be as follows for data frame's B part:

> df21223$B
[1]  3 NA NA  5 NA NA  7

Where Sample data is:

> df21223$A
[1]  3 NA NA  5 NA NA  7
> df21223$B
[1] NA NA NA NA NA NA NA

2 Answers2