# Creating a Stratified Random Sample of a Dataframe

[This article was first published on

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

Expanding on a question on Stack Overflow I’ll show how to make a stratified random sample of a certain size: **theBioBucket***, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

d <- expand.grid(id = 1:35000, stratum = letters[1:10]) p = 0.1 dsample <- data.frame() system.time( for(i in levels(d$stratum)) { dsub <- subset(d, d$stratum == i) B = ceiling(nrow(dsub) * p) dsub <- dsub[sample(1:nrow(dsub), B), ] dsample <- rbind(dsample, dsub) } ) # size per stratum in resulting df is 10 % of original size: table(dsample$stratum)

To

**leave a comment**for the author, please follow the link and comment on their blog:**theBioBucket***.R-bloggers.com offers

**daily e-mail updates**about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.