Creating a new columns based on values from existing multiple columns

Question

I need to create a new column named "condition" (which is not there initially) based on the first three columns. If the values are from cond1 then it should be 1 in my condition column and so on. Any suggestions.

cond_test = read.csv("https://www.dropbox.com/s/du76g4vlfz2uaph/cond_test.csv?dl=1")
cond_test
#>   ï..cond1 cond2 cond3 condition
#> 1        2    NA    NA         1
#> 2        4    NA    NA         1
#> 3       NA     3    NA         2
#> 4       NA     5    NA         2
#> 5       NA     4    NA         2
#> 6       NA    NA     1         3
#> 7       NA    NA     4         3
#> 8       NA    NA     7         3

Ronak Shah · Accepted Answer · 2020-11-04 07:41:46Z

1

You can use max.col to get first non-NA value in each row.

max.col(!is.na(cond_test))
#[1] 1 1 2 2 2 3 3 3

If you have more than one non-NA value in the row you can look at ties.method argument in ?max.col on how to handle ties.

In dplyr you can use rowwise :

library(dplyr)
cond_test %>%
  rowwise() %>%
  mutate(condition = which.max(!is.na(c_across())))

edited Nov 4, 2020 at 7:41

answered Nov 4, 2020 at 7:32

Ronak Shah

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4 Comments

Ramakrishna S Over a year ago

r> max.col(!is.na(cond_test)) [1] 4 4 2 4 4 4 5 3 is what I am getting. Can you please share complete code.

Ronak Shah Over a year ago

@RamakrishnaS I am assuming there is no condition column in your data as mentioned in your post. cond_test$condition <- NULL

Ramakrishna S Over a year ago

I removed condition, and ran the dplyr code. I got this error.

r Error: Problem with `mutate()` input `condition`. x Input `condition` can't be recycled to size 1. i Input `condition` is `which(!is.na(c_across()))`. i Input `condition` must be size 1, not 2. i Did you mean: `condition = list(which(!is.na(c_across())))` ? i The error occurred in row 1.

Ronak Shah Over a year ago

@RamakrishnaS Unlike the example shared you have rows in your data where there are more than 1 value. I have used whcih.max to select the 1st one.

Ramakrishna S · Accepted Answer · 2020-11-04 08:29:16Z

0

I tried the following code and is working. But any elegant solutions are welcome.

cond_test$condition = ifelse(!is.na(cond_test$ï..cond1), 1, 
                             ifelse(!is.na(cond_test$cond2), 2, 3))

answered Nov 4, 2020 at 8:29

Ramakrishna S

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