Count how many times strings from one data frame appear to another data frame in R dplyr

Question

I have two data frames that look like this:

df1 <- data.frame(reference=c("cat","dog"))
print(df1)
#>   reference
#> 1       cat
#> 2       dog
df2 <- data.frame(data=c("cat","car","catt","cart","dog","dog","pitbull"))
print(df2)
#>      data
#> 1     cat
#> 2     car
#> 3    catt
#> 4    cart
#> 5     dog
#> 6     dog
#> 7 pitbull

^{Created on 2021-12-29 by the reprex package (v2.0.1)}

I want to find how many times the words cat and dog from the df1 exist in df2. I want my data to look like this

animals   n
cat       1
dog       2

Any help or guidance is appreciated. My reference list is huge. I tried to grep each one of them but ll take me time.

Thank you for your time. Happy holidays

Answer 1

A possible solution, tidyverse-based:

library(tidyverse)

df1 <- data.frame(reference=c("cat","dog"))
df2 <- data.frame(data=c("cat","car","catt","cart","dog","dog","pitbull"))

df1 %>% 
  group_by(animal = reference) %>% 
  summarise(n = sum(reference == df2$data), .groups = "drop")

#> # A tibble: 2 × 2
#>   animal     n
#>   <chr>  <int>
#> 1 cat        1
#> 2 dog        2