Use lapply with a built-in R function
Before you go about solving the exercises below, have a look at the documentation of the lapply() function. The Usage section shows the following expression:
lapply(X, FUN, ...)
To put it generally, lapply takes a vector or list X, and applies the function FUN to each of its members. If FUN requires additional arguments, you pass them after you've specified X and FUN (...). The output of lapply() is a list, the same length as X, where each element is the result of applying FUN on the corresponding element of X.
Now that you are truly brushing up on your data science skills, let's revisit some of the most relevant figures in data science history. We've compiled a vector of famous mathematicians/statisticians and the year they were born. Up to you to extract some information!
This exercise is part of the course
Intermediate R
Exercise instructions
- Have a look at the
strsplit()calls, that splits the strings inpioneerson the:sign. The result,split_mathis a list of 4 character vectors: the first vector element represents the name, the second element the birth year. - Use
lapply()to convert the character vectors insplit_mathto lowercase letters: applytolower()on each of the elements insplit_math. Assign the result, which is a list, to a new variablesplit_low. - Finally, inspect the contents of
split_lowwithstr().
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# The vector pioneers has already been created for you
pioneers <- c("GAUSS:1777", "BAYES:1702", "PASCAL:1623", "PEARSON:1857")
# Split names from birth year
split_math <- strsplit(pioneers, split = ":")
# Convert to lowercase strings: split_low
# Take a look at the structure of split_low