Search for text in one column within a string in another column

Question

Newbie to R here. Been searching this forum to try and find a way to search for text within a string in the same row of data. I've used grepl before, but I can't get it to look down a column and apply the check for each row. I feel like this is an easy solution, but I've spent a few hours on it and can't seem to get it.

Basically I have something like column 1 below and need it to check if the text in column 2 is within column one, then return true or false in a new column.

column 1         column2     result
Target_US_Toy    _US_        TRUE
Target_CA_Toy    _MX_        FALSE
Target_NZ_Toy    _NZ_        TRUE

Thank you!

score 1 · Accepted Answer · edited Jun 19 '18 at 17:06

1

Using str_detect from the stringr pacakge:

library(stringr)
str_detect(df1$column1, df1$column2)

[1]  TRUE FALSE  TRUE

or using only base R combining grepl with apply:

apply(df1,1, function(x){
  grepl(x[2], x[1])
})
[1]  TRUE FALSE  TRUE

edited Jun 19 '18 at 17:06

IRTFM

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answered Jun 19 '18 at 17:01

GordonShumway

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Thank you!!! I've mainly been using dplyr and haven't gotten to stringr yet. Should probably take my next course on that – Tyler Jun 19 '18 at 17:11

score 1 · Answer 2 · answered Jun 19 '18 at 17:01

We can do this using stringr.

First, let's create a data frame:

df <- data.frame(column1 = c("Target_US_Toy", "Target_CA_Toy"),
                 column2 = c("_US_", "_NZ_"),
                 stringsAsFactors = FALSE)

Next, we create a new column called result:

library(stringr)
df$result = str_detect(string = df$column1, pattern = df$column2)

score 0 · Answer 3 · answered Jun 19 '18 at 17:09

0

You can also use grepl with Map

unlist(Map(grepl, df$column2, df$column1))

Output:

 #_US_  _MX_  _NZ_ 
 #TRUE FALSE  TRUE

answered Jun 19 '18 at 17:09

PKumar

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score 0 · Answer 4 · answered Jun 19 '18 at 17:12

The base method would be to use mapply to deliver a "parallel" set of arguments to a function that is not vectorized in one or more of its argument positions:

dat$ result <- mapply(grepl, dat$column2, dat$column1)

> dat
        column1 column2 result
1 Target_US_Toy    _US_   TRUE
2 Target_CA_Toy    _MX_  FALSE
3 Target_NZ_Toy    _NZ_   TRUE

Search for text in one column within a string in another column

4 Answers4

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