join without middle name in r

To join two columns in R without including the middle name, you can use the paste() function along with the gsub() function. Here's an example:

Suppose you have a data frame where the first name, middle name, and last name are separate columns:

main.r
df <- data.frame(first_name = c("John", "Sarah", "Michael"),
                 middle_name = c("Andrew", "Jane", ""),
                 last_name = c("Smith", "Johnson", "Davis"))
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You can create a new column that concatenates the first and last names, but excludes the middle name, like this:

main.r
df$full_name <- paste(df$first_name, gsub("\\s.*\\s", " ", df$middle_name), df$last_name)
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In the gsub() function, we use a regular expression argument to match and remove any string that contains spaces (i.e. the middle name). The \\s characters match any whitespace, and .* matches any characters (except a newline), zero or more times. The paste() function then concatenates the first and last names with the modified middle name.

The resulting data frame would look like this:

main.r
  first_name middle_name last_name    full_name
1       John      Andrew     Smith  John Smith
2      Sarah        Jane   Johnson Sarah Johnson
3    Michael                    Davis Michael Davis
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Note that the third row does not have a middle name, and therefore the resulting full_name is just the concatenation of the first and last names.