I'm generating a set of densities using functions like dweibull and dunif. I'd like to be able to extract their moments using sapply. When I call the mean function on individual distributions, I get the mean value as expected. But when I do this with sapply, instead it seems to call mean() on every individual value in the density (i.e. for every value of x I supplied to dweibull or dunif. Is there a way to get the correct behavior here? Thank you!

weib <- dweibull(seq(from=0, to=25, length=100), shape=1, scale=5)
unif <- dunif(seq(from=1, to=10, length=100), min=1, max=10)
mean(weib) #Works!
dists <- c(weib, unif)
means <- sapply(dists, mean) #Returns a very long list of values, not the mean of weib and unif

CodePudding user response：

You should store the data in a list. c(weib, unif) creates a single combined vector and using sapply(dists, mean) returns the mean of single number i.e the number itself.

dists <- list(weib, unif)
means <- sapply(dists, mean) 

CodePudding user response：

You can also use dataframe

dists <- data.frame(weib, unif)
sapply(dists, mean)
      weib       unif 
0.04034828 0.11111111 
lapply(dists,mean)
$weib
[1] 0.04034828

$unif
[1] 0.1111111
apply(dists, 2,mean)
      weib       unif 
0.04034828 0.11111111