从数据帧,是否有聚集(一个简单的方法sum,mean,max同时等c)中多个变量？
以下是一些示例数据:
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)
我想同时按年和月汇总数据框中的变量x1和x2变量df2.以下代码聚合x1变量,但是是否也可以同时聚合x2变量？
### aggregate variables by year month
df2=aggregate(x1 ~ year+month, data=df1, sum, na.rm=TRUE)
head(df2)
任何建议将不胜感激.