Find top deciles from dataframe by group

Question

I am attempting to create new variables using a function and lapply rather than working right in the data with loops. I used to use Stata and would have solved this

Answer 1

You don't need the function pf to achieve what you want. Try dplyr/tidyr combo

library(dplyr)
library(tidyr)
data %>% 
    group_by(v1) %>% 
    arrange(desc(v2))%>%
    mutate(n=n()) %>% 
    filter(row_number() <= round(n * .2)) %>% 
    mutate(top_pct= ifelse(row_number()<=round(n* .1), 10, 20)) %>%
    select(custID, top_pct) %>% 
    spread(v1,  top_pct)
#  custID  A  B
#1      1 10 10
#2      2 20 20
#3      6 NA 10
#4      7 NA 20