How to check if a string in one element of a dataframe row is in another element

user_7157342 0
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I want to see how many email addresses contain the last name of the email's owner.

Each row in a dataframe contains a last name and an email address. I want to add a third column with a "yes" or a "no" indicating the presence of the last name in the email on that row.

Using a for loop works fine...but I can't help thinking there's probably a better R solution. Any suggestions on how make this more elegant?

vec1 <- c("foo", "smith")
vec2 <- c("sfoo@x.com", "xxx@y.com")

df <- data.frame(vec1,vec2)


for(i in 1:nrow(df)) {
  if (grepl(df$vec1[i], df$vec2[i]) == TRUE) {
    df$lastNameInEmail[i] <- "Yes"
  } else {
    df$lastNameInEmail[i] <- "No"
  }
}

   vec1       vec2 lastNameInEmail
1   foo sfoo@x.com             Yes
2 smith  xxx@y.com              No
grepl r
3 Answers

You can using stringr str_detect

stringr::str_detect(vec2,paste(vec1,collapse = '|'))
[1]  TRUE FALSE
user_79645270

Here is a data.table alternative which works for more than the two given rows:

vec1 <- c("foo", "smith", "jones", "bar")
vec2 <- c("sfoo@x.com", "xxx@y.com", "yyy@x.com", "sbar@x.com")

df <- data.frame(vec1,vec2)

library(data.table)
dt <- data.table(df)
dt[, lastNameInEmail:=ifelse(grepl(vec1, vec2) == TRUE, "Yes", "No"), by=vec1]
dt
    vec1       vec2 lastNameInEmail
1:   foo sfoo@x.com             Yes
2: smith  xxx@y.com              No
3: jones  yyy@x.com              No
4:   bar sbar@x.com             Yes

This assumes that the vec1 column is unique though.

user_1001290

Here is a version using base R functions which works for more than the two given rows:

vec1 <- c("foo", "smith", "jones", "bar")
vec2 <- c("sfoo@x.com", "xxx@y.com", "yyy@x.com", "sbar@x.com")

df <- data.frame(vec1,vec2)

df$lastNameInEmail <- sapply(1:nrow(df), function(x){ifelse(grepl(df$vec1[x], df$vec2[x])==TRUE, "Yes", "No")})
df
    vec1       vec2 lastNameInEmail
1:   foo sfoo@x.com             Yes
2: smith  xxx@y.com              No
3: jones  yyy@x.com              No
4:   bar sbar@x.com             Yes
user_1001290
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