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 https://www.riffomonas.org/code_club/....

The data were generated in our Kozich et al. 2013 paper (http://doi.org/10.1128/AEM.01043-13) using samples from the Schloss et al. 2012 paper (http://doi.org/10.4161/gmic.21008).

#list #lapply #R #Rstats #baseR

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If you're interested in taking an upcoming 3 day R workshop be sure to check out our schedule at https://riffomonas.org/workshops/

You can also find complete tutorials for learning R with the tidyverse using...
Microbial ecology data: https://www.riffomonas.org/minimalR/
General data: https://www.riffomonas.org/generalR/

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