odd reordering by dplyr::slice

slice_reorders.R

library(tidyverse)

# create a list of length 10 with a small dataframe in each entry
df <- lapply(1:10,function(x){data.frame(y = 1:5)})

# convert to tbl
df_tbl<- bind_rows(df, .id = "id")

# pluck out the last entry for each "id" using slice()
last_entry <- df_tbl %>% group_by(id) %>% slice(n())
print(last_entry)
# note that id = 10 appears second in the list.

# instead we have to coerce df_tbl$id to be a factor
df_tbl_2 <- bind_rows(df, .id = "id") %>% mutate(id = factor(as.numeric(id)))

last_entry_2 <- df_tbl_2 %>% group_by(id) %>% slice(n())

print(last_entry_2)