Code: Avoid copy-on-modify with data.table

- [Instructor] R provides a range of data structures,…things like lists, vectors, and matrices.…Data frames are probably the most convenient way…to store data, they behave very much like a spreadsheet,…but R does some strange things, memory wise,…when you start to copy, append, and change data frames.…Let's take a look at how that works,…and then I'll show you a solution for using data frames…without the memory side effects.…The first thing I'm going to do…is create something called aDataFrame,…and it's a subset of the UCS Satellite data set.…

You can see over in the environment, it's,…aDataFrame has 1,886 observations of three variables,…and we can see how big that actually is…using line 11, where it says object.size aDataFrame.…Down in the console, it indicates that that's 39,000 bytes.…Well, I'd like to watch what happens DataFrame…as I make modifications to it,…and we know from a previous video…that tracemem will tell us any time…that an object is copied, so let's use line 13,…where I turn on tracemem for aDataFrame,…