Indexing and looping over lists in R, a tutorial (CC174)

Lists are an important, but underappreciated type of data in R. In this Code Club, Pat gives a tutorial on indexing or accessing values from a list and then shows how we can iterate over the values of a list using the lapply function. Along the way we'll see how we can unlist lists and convert them into matrices as well as generate the transpose of a matrix with the t function. This is part of a series of videos demonstrating how to functions from base R to make these data compatible with tools from the tidyverse

#list #lapply #R #Rstats #baseR

You can also find complete tutorials for learning R with the tidyverse using...

0:00 Using lists and lapply to replace a for loop
1:31 Parsing a file on line breaks with scan
3:53 Splitting text data with strsplit
5:57 How to access values from a list
8:35 Creating a function to make list elements the same length
11:43 Iterating a function over values in a list with lapply
16:14 Converting lower triangular matrix to a full matrix

[mocabeentrill]

Wow! Thanks Pat. This was the most advanced episode in the series and it requires one to be well versed in the intricacies of base R. Thoroughly enjoyed it!

[CBG]

Your explanation that dataframes are actually lists of vectors blew my mind. None of my instructors have ever made that explicit!

Learning a lot from your videos. Happy holidays!

[luisandresmorenocueva]

Merry xmas. Thx for the videos of this year

[marcossahade]

very interesting lessons .. congrats from Argentina

[domenicoscarpino]

Hi, thanks a lot for the great content.
I don't seem to be able to explain why they included [, 1] in the code below. I was checking a solved exercise and found this code, so I thought I could maybe ask here about the theoretical explanation behind that specific part. I would have thought that Data[, i] was enough to make it work. Thanks in advance.

for(i in c(2, 6:11)){
a=(abs(scale(Data[, i])[, 1])<3)
Data=Data[a, ]
}