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
You can find my blog post for this episode at www.riffomonas....
The data were generated in our Kozich et al. 2013 paper (doi.org/10.1128...) using samples from the Schloss et al. 2012 paper (doi.org/10.4161....
#list #lapply #R #Rstats #baseR
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You can also find complete tutorials for learning R with the tidyverse using...
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General data: www.riffomonas...
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
13:51 Merging elements of a list with unlist and do.call
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!

[@Riffomonas]

wonderful! sometimes it's fun to go into the weeds a bit :)

[@CBG91]

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

[@Riffomonas]

Wonderful! Thanks for watching 😊

[@dimamedvedev4124]

great exapmles and smart explanation

Learning a lot from your videos. Happy holidays!

[@Riffomonas]

Hi Victor - wonderful! Thanks for watching

[@marcossahade9369]

very interesting lessons .. congrats from Argentina

[@Riffomonas]

Hi Marcos - Thanks for watching!

[@luisandresmorenocueva3399]

Merry xmas. Thx for the videos of this year

[@Riffomonas]

Thanks Luis! Have a great Christmas 😊

[@tlange5091]

Thank you so much for your videos!

[@Riffomonas]

My pleasure! Thanks for tuning in 🤓

[@oluwafemioyedele]

Nice tutorial!!!

[@Riffomonas]

Thanks- glad it was useful!

[@domenicoscarpino3715]

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])

[@Riffomonas]

Thanks for the question. Unfortunately, I am unable to answer questions like this in comments. I'd encourage you to ask on StackOverflow or on the RStudio forum

[@roymccormick5328]

cool thx

[@Riffomonas]

Thanks for watching!