# Custom Summary Stats as Dataframe or List

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On Stackoverflow I found this useful example on how to apply custom statistics on a dataframe and return the results as list or dataframe:**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.

somedata<- data.frame( year=rep(c(1990,1995,2000,2005,2010),times=3), country=rep(c("US", "Brazil", "Asia"), each=5), pct = c(0.99, 0.99, 0.98, 0.05, 0.9, 0.4, 0.5, 0.55, 0.5, 0.45, 0.7, 0.85, 0.9, 0.85, 0.75) ) someStats <- function(x) { dp <- as.matrix(x$pct)-mean(x$pct) indp <- as.matrix(x$year)-mean(x$year) f <- lm.fit( indp,dp )$coefficients w <- sd(x$pct) m <- min(x$pct) results <- c(f,w,m) names(results) <- c("coef","sdev", "minPct") results } # summary statistics as list with by(): by(somedata, list(country=somedata$country), someStats) # ..or as dataframe with ddply(): library(plyr) ddply(somedata, .(country), someStats)

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