Collapsing Lists In R

Kevin Feasel

2016-04-06

R

Steph Locke shows how to collapse a list of data frames into a single data table:

With my HIBPwned package, I consume the HaveIBeenPwned API and return back a list object with an element for each email address. Each element holds a data.frame of breach data or a stub response with a single column data.frame containing NA. Elements are named with the email addresses they relate to. I had a list of data.frames and I wanted a consolidated data.frame (well, I always want a data.table).

Enter data.table …

data.table has a very cool, and very fast function named rbindlist(). This takes a list of data.frames and consolidates them into one data.table, which can, of course, be handled as a data.frame if you didn’t want to use data.table for anything else.

Something that continuously amazes me with R is just how terse the language can be without collapsing into Perl.

Related Posts

Inline Operators In R With wrapr

John Mount shows how to use inline operators in R with the wrapr package: The above code is assuming you have the wrapr package attached via already having run library('wrapr'). Notice we picked R-related operator names. We stayed away from overloading the + operator, as the arithmetic operators are somewhat special in how they dispatch in R. The goal wasn’t […]

Read More

Feature And Text Classification Using Naive Bayes In R

I wrap up my series on the Naive Bayes class of algorithms, finally writing some code along the way: Now we’re going to look at movie reviews and predict whether a movie review is a positive or a negative review based on its words. If you want to play along at home, grab the data set, […]

Read More

Categories

April 2016
MTWTFSS
« Mar May »
 123
45678910
11121314151617
18192021222324
252627282930