R dplyr create function to display/print number of rows with matching records/values in two datafram-CodePudding

Based on the code and data below how can I get a print of number of rows (count) with matching values in two dataframes?

The number of matching records between [insert dataframe 1 name] and [insert dataframe 2 name] are X based on [insert matching column name].

I know I can look at the display in the console to do this, but I guess printing the above message might also be a good idea especially when there are big datasets involved. For this I might have to create a function, and my function creating skills are not so polished at the moment.

Code data:

    library(tidyverse)
    
    # Dummy data
    df1 = data.frame(v1 = c(1,2,3,4,5,6,7,8), 
                    v2 = c("A","E","C","B","B","C","A","E"))
    
    df2 = data.frame(v2 = c("D","E","A","C","D","B"), 
                    v3 = c("d","e","a","c","d","b")) 
    
    # Match values
    df_new = df1 %>%
        mutate(v2= as.character(v2)) %>% 
        left_join(df2) 

# Write code to print the number of matching records, stuck!!!
# The number of matching records between [insert dataframe 1 name] and [insert dataframe 2 name] are X based on [insert matching column name].

CodePudding user response：

I like to use the tidylog-package for this.

This handy package wraps most dplyr functions including *_join's and offers print-outs for several of these (also filter, distinct, mutate, etc.). However, because it's a wrapper it also hides the help and (in RStudio) autocomplete, why I seldom loads the package with library(tidylog), instead I call it with tidylog:::

library(dplyr)

df_new <- df1 |>
  mutate(v2 = as.character(v2)) |>
  tidylog::left_join(df2)

Output:

Joining, by = "v2"
left_join: added one column (v3)
           > rows only in x   0
           > rows only in y  (2)
           > matched rows     8
           >                 ===
           > rows total       8