number of rows by group in r
# dplyr package does this with count/tally commands, or the n() function:
# First, some data:
df <- data.frame(x = rep(1:6, rep(c(1, 2, 3), 2)), year = 1993:2004, month = c(1, 1:11))
# Now the count:
library(dplyr)
count(df, year, month)
# piping
df %>% count(year, month)
# We can also use a slightly longer version with piping and the n() function:
df %>%
group_by(year, month) %>%
summarise(number = n())
dplyr package does this with count/tally commands, or the n() function:
# First, some data:
df <- data.frame(x = rep(1:6, rep(c(1, 2, 3), 2)), year = 1993:2004, month = c(1, 1:11))
# Now the count:
library(dplyr)
count(df, year, month)
# piping
df %>% count(year, month)
# We can also use a slightly longer version with piping and the n() function:
df %>%
group_by(year, month) %>%
summarise(number = n())
# or the tally function:
df %>%
group_by(year, month) %>%
tally()