More accurate implemmentation of spread()

[krlmlr]

The spread() verb won't work for data frames if there are duplicates in the keys. It is unfortunate that PIVOT() seems to require an aggregation function, I haven't found a way to write this operation so that no aggregates are performed (but an error is returned instead). Perhaps with a user-defined function?

Either way, FIRST_VALUE() seems to be a slightly better choice than MAX(), because it might also work for non-numeric data.

library(tidyverse)
data <- tibble(a = c(1, 1, 2), b = a, c = 4:6)
data %>%
  spread(b, c)
#> Error: Duplicate identifiers for rows (1, 2)

Created on 2018-05-20 by the reprex package (v0.2.0).