String length

Our next stringr function is str_length(). str_length() takes a vector of strings as input and returns the number of characters in each string. For example, try finding the number of characters in Batman's name:

str_length(c("Bruce", "Wayne"))

This is very similar to the base function nchar() but you'll see in the exercises str_length() handles factors in an intuitive way, whereas nchar() will just return an error.

Historically, nchar() was even worse, rather than returning an error if you passed it a factor, it would return the number of characters in the numeric encoding of the factor. Thankfully this behavior has been fixed, but it was one of the original motivations behind str_length().

Take your first look at babynames by asking if girls' names are longer than boys' names.

We've pulled out just the names from 2014, and created the vectors boy_names and girl_names for you. (If you want to learn about the filter() function, take the Data Manipulation in R with dplyr course!).

Take a look at the boy_names vector, it's long, so use head() to see the first few elements.
Use str_length() on boy_names to find the length of each name and save the result to boy_length.
Take a look at the lengths. Again, use head(). Can you see the correspondence with boy_names?
Find the length of all the girls' names. Call this girl_length.
Find the difference in mean length between boys' and girls' names by subtracting the mean length of boys' names from that of girls' names.
Confirm str_length() works on factors, by calling it on factor(boy_names). Again, you'll want to just look at the head().

Exercise

String length

Instructions