# NOT RUN {
test_df <- data.table(
x = 1:3,
y = 4:6,
z = c("a","a","b")
)
test_df %>%
summarize.(count = n.(), .by = z)
# The dplyr version `n()` also works
test_df %>%
summarize.(count = n(), .by = z)
# }
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