Faster ways to calculate frequencies and cast from long to wide

Question

I am trying to obtain counts of each combination of levels of two variables, \"week\" and \"id\". I\'d like the result to have \"id\" as rows, and \"week\" as columns, and t

Answer 1

A tidyverse option could be :

library(dplyr)
library(tidyr)

df %>%
  count(id, week) %>%
  pivot_wider(names_from = week, values_from = n, values_fill = list(n = 0))
  #spread(week, n, fill = 0) #In older version of tidyr

#     id   `1`   `2`   `3`
#      
#1     1     2     1     1
#2     2     0     0     1

---

Or using tabyl from janitor :

janitor::tabyl(df, id, week)
# id 1 2 3
#  1 2 1 1
#  2 0 0 1

data

df <- structure(list(id = c(1L, 1L, 1L, 1L, 2L), week = c(1L, 2L, 3L, 
1L, 3L)), class = "data.frame", row.names = c(NA, -5L))