How calculate average values for lists in R tibble?

Question

Let say I have R tibble

  df <- tibble(
    name = c("x", "y"),
    prob = list(c(1,2,3), c(4,5,6))
  )

How calculate average of values for "prob" field.

Expected result is a list with values c((1+4)/2, (2+5)/2, (3+6)/2) => c(2.5, 3.5, 4.5)

Answer 1

Use Reduce to get element-wise addition and divide it by number of rows in the dataframe.

Reduce(`+`, df$prob)/nrow(df)
#[1] 2.5 3.5 4.5

Other alternatives with rowMeans and colMeans.

colMeans(do.call(rbind, df$prob))
rowMeans(do.call(cbind, df$prob))