Replace blank values in one column based on partial string values of another in R

Question

I have data that looks like the following:

pig<-data.frame(a=c("","","","","","Type1"),b=c("T1 NR","T2 NR","T2","T3","T3","Type1"))
print(pig)
  a      b
       T1 NR
       T2 NR
       T2
       T3
       T3
Type1  Type 1

Where a will sometimes be blank, but b always has information that corresponds to the missing information in a. I am looking for two things. First, where "NR" is present in b, I want "NR" to appear in a. Second, where "NR" is not present in b and a is blank, I would like some other string to appear in such as "DKT" to get something like the following:

cow<-data.frame(a=c("NR","NR","DKT","DKT","DKT","Type1"),b=c("T1 NR","T2 NR","T2","T3","T3","Type1"))
print(cow)
 a     b
NR   T1 NR
NR   T2 NR
DKT   T2
DKT   T3
DKT   T3
Type1 Type1

Thanks!

Try library(tidyverse);pig %>% mutate(a = case_when(str_detect(b, "NR") ~"NR", a == "" ~ "DKT", TRUE ~ as.character(a))) — akrun
– akrun, Commented Jan 22, 2018 at 18:37
Using ifelse ifelse(pig$a == "", ifelse(grepl("NR", pig$b), "NR", "DKT"), as.character(pig$a)) — zx8754
– zx8754, Commented Jan 22, 2018 at 18:39

Nathan Werth · Accepted Answer · 2018-01-22 19:17:47Z

1

You can assign using row/column subsetting with a data.frame.

# You're doing string editing, so let's avoid factors from the start
pig <- data.frame(
  a = c("","","","","","Type1"),
  b = c("T1 NR","T2 NR","T2","T3","T3","Type1"),
  stringsAsFactors = FALSE
)

# The actual solution
has_nr <- grepl("NR", pig$b)
pig[has_nr, "a"] <- "NR"
pig[!has_nr & pig$a == "", "a"] <- "DKT"

answered Jan 22, 2018 at 19:17

Nathan Werth

5,37320 silver badges25 bronze badges

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

6 Comments

costebk08 Over a year ago

I get an error when applying the last line: Error in chatToDate(x): character string is not in a standard unambiguous format I think it might be an issue with the blanks, which could be a different question. However, any thoughts?

Nathan Werth Over a year ago

What's the class of the a column in your dataset? Is it a Date vector?

costebk08 Over a year ago

It is class character

Nathan Werth Over a year ago

I'm guessing the error actually says charToDate instead of chatToDate. If so, somewhere in your code you're attempting to convert a character value to a Date, but it's unclear how to interpret it. Even if you're not calling as.Date() yourself, you might be assigning a value into a Date vector.

costebk08 Over a year ago

You are correct, that was a typo. I convert another column to a date, but not the one I am working on. What would be the best way to go about fixing the issue?

|

Collectives™ on Stack Overflow

Replace blank values in one column based on partial string values of another in R

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related