ifelse statement only returns else values (when combined with mutate() and %in%)

[Bolleke]

I have a series of files in my directory that look like this

Title A.txt
Title A.txt
Title A.txt
Title A.txt
Title A.txt
Title B.txt
Title B.txt
Title B.txt

my code for preprocessing looks like this,

all <- readtext("*.txt")

tidy.all <- all %>%
unnest_tokens(word, text) %>%
anti_join(stop_words)%>%
mutate(party = ifelse(doc_id %in% "A", "a", "b"))

the problem arises with the mutate function when I'm trying to add a new column, it only returns the else values for the entire dataframe and I don't know why it's doing that. I've tried to apply the same function on austen_books and there it works. I've even changed the doc_id variable into factors but to no avail.

library(janeaustenr)

books <- austen_books() %>%
mutate(party = ifelse(book %in% "Sense & Sensibility", "a", "b"))

[andresrcs]

To help us help you, could you please prepare a reproducible example (reprex) illustrating your issue? Please have a look at this guide, to see how to create one:

FAQ: How to do a minimal reproducible example ( reprex ) for beginners

A minimal reproducible example consists of the following items: A minimal dataset, necessary to reproduce the issue The minimal runnable code necessary to reproduce the issue, which can be run on the given dataset, and including the necessary information on the used packages. Let's quickly go over each one of these with examples: Minimal Dataset (Sample Data) You need to provide a data frame that is small enough to be (reasonably) pasted on a post, but big enough to reproduce your issue. Let's say, as an example, that you are working with the iris data frame head(iris) #> Sepal.Length Sepal.Width Petal.Length Petal.Width Species #> 1 5.1 3.5 1.4 0.…

[Bolleke]

Thank you for wanting to help

here's a reprex that has the same issue

doc_id <- c("Title A.txt",
"Title A.txt",
"Title B.txt",
"Title B.txt",
"Title B.txt")

df <- as.data.frame(doc_id)

df$category <- ifelse(doc_id %in% "A", "A", "B")

result

df
doc_id category
1 Title A.txt B
2 Title A.txt B
3 Title B.txt B
4 Title B.txt B
5 Title B.txt B

What's weird is if I use the entire doc_id string in ifelse() like so

df$category <- ifelse(doc_id %in% "Title A.txt ", "A", "B")

then it does return what I want, the problem is that the only thing I can differentiate the documents is through the A & B element

[siddharthprabhu]

That's not how the %in% operator works. Is this what you are trying to do?

doc_id <- c("Title A.txt",
            "Title A.txt",
            "Title B.txt",
            "Title B.txt",
            "Title B.txt")

df <- as.data.frame(doc_id)

df$category <- ifelse(grepl("A", doc_id), "A", "B")

print(df)
#>        doc_id category
#> 1 Title A.txt        A
#> 2 Title A.txt        A
#> 3 Title B.txt        B
#> 4 Title B.txt        B
#> 5 Title B.txt        B

^{Created on 2020-04-11 by the reprex package (v0.3.0)}

[Bolleke]

Yes, that does it, thank you very much!
May I ask why the %in% operator wouldn't work in this instance?

[siddharthprabhu]

Because you're trying to do a partial match. %in% will give you your desired result only if the entire string is found in the target vector. For partial matches, you have to go with grep() or similar pattern matching functions.

# This works.
doc_id %in% "Title A.txt"
[1]  TRUE  TRUE FALSE FALSE FALSE

# This doesn't.
doc_id %in% "A"
[1] FALSE FALSE FALSE FALSE FALSE