Converting a categorical variable to multiple binary variables [duplicate]

Answer 1

For a tidy approach

library(dplyr)
library(tidyr)
library(tibble)

mydf %>%
  rownames_to_column() %>%
  group_by(rowname, transaction, quality, brand) %>%
  summarise(count = n()) %>%
  spread(brand, count, sep = "-", fill = 0) %>%
  ungroup() %>%
  select(-rowname)

# # A tibble: 7 x 5
#   transaction quality `brand-1` `brand-2` `brand-3`
# *                        
# 1           1     NEW         1         0         0
# 2           0     OLD         0         1         0
# 3           1     OLD         0         0         1
# 4           1     OLD         1         0         0
# 5           1     OLD         0         1         0
# 6           0     NEW         0         1         0
# 7           0     NEW         1         0         0