The timing of this post is pretty great! I work a lot with "largish files" in R, and while R has gotten much better at reading big files (thanks to data.table's

The timing of this post is pretty great! I work a lot with "largish files" in R, and while R has gotten much better at reading big files (thanks to data.table's fread), often times you really don't want to work with the whole file. I was surprised that there wasn't a tool to sample from a stream. I wrote a simple perl script https://github.com/earino/fast_sample https://github.com/earino/fast_sample to do just that. I was "getting around" the issue of needing reservoir sampling by allowing the user to pass in a "proportion of lines" (e.g. .01 for 1%). I realized that I needed to add the ability to sample an exact number of records, so I went ahead and implemented reservoir sampling. It's a neat algorithm and the performance is pretty stellar. Now I just need to expand it to allow stratified sampling on a column! :)