找到十年来的最高价值

Question

我在R中有这个数据框:

set.seed(1)
count <- sample(1:100, 100, replace = TRUE)

set.seed(2)
year <- sample(1970:2015, 100, replace = TRUE)

library(dplyr)

df <- data_frame(count, year)

df

Source: local data frame [100 x 2]

   count year
1     27 1978
2     38 2002
3     58 1996
4     91 1977
5     21 2013
6     90 2013
7     95 1975
8     67 2008
9     63 1991
10     7 1995
..   ...  ...

我怎样才能找到每十年(70s ... 10s)的最高数量？

Answer 1

使用dplyr:

library(dplyr)

df %>% group_by(floor(year/10)*10) %>% summarise(max_cnt = max(count))