-1

I need to match a string in the first variable with a string in the second variable and then return true or false in the third column.

Here is my data

regex <- c("cat", "dog", "mouse") 
text<- c("asdf.cat/asdf", "asdf=asdf", "asdf=mouse asdf")
df <- data.frame(regex, text)```

And I need an output like this

regex text result
cat asdf.cat/asdf 1
dog asdf=asdf 0
mouse asdf=mouse asdf 1

I have tried using grepl but I cant figure out how to use it in a dataframe.

df$result <- as.integer(grepl("cat", df$text))

This will work for the first row only

I have also tried the following code which works to filter out the matches but I want to keep them all in and just return true or false.

df %>%
  filter(unlist(Map(function(x, y) grepl(x, y), regex, text)))

As you can see it is complicated by the text string containing various characters

I feel like this should be easy but I cant wrap my head round it!!

oguz ismail
  • 1
  • 16
  • 47
  • 69
Ellie Sparling
  • 9
  • 1

1 Answers1

3

Instead of grepl, use str_detect which is vectorised for the pattern and string

library(stringr)
library(dplyr)
df %>%
    mutate(result= +(str_detect(text, regex)))

-output

   regex            text result
1   cat   asdf.cat/asdf      1
2   dog       asdf=asdf      0
3 mouse asdf=mouse asdf      1

data

df <- structure(list(regex = c("cat", "dog", "mouse"), text = c("asdf.cat/asdf", 
"asdf=asdf", "asdf=mouse asdf")), class = "data.frame", row.names = c(NA, 
-3L))
akrun
  • 874,273
  • 37
  • 540
  • 662