从数据帧来看,有没有一种简单的方法可以同时聚合(sum
mean
max
ETC)多个变量?
以下是一些样本数据:
library(lubridate)
days = 365*2
date = seq(as.Date("2000-01-01"), length = days, by = "day")
year = year(date)
month = month(date)
x1 = cumsum(rnorm(days, 0.05))
x2 = cumsum(rnorm(days, 0.05))
df1 = data.frame(date, year, month, x1, x2)
我想同时将df2
个数据框中的x1
和x2
个变量按年份和月份进行汇总.下面的代码聚合了x1
个变量,但也可以同时聚合x2
个变量吗?
### aggregate variables by year month
df2=aggregate(x1 ~ year+month, data=df1, sum, na.rm=TRUE)
head(df2)