[关键字]:
do not use aggregate
[出处]:
http://www.r-bloggers.com/dont-use-statsaggregate/
[重点摘要]:
Most base R code has problems if there are extra attributes on a numeric
array. So R-stat code tends to have a habit of dropping attributes when it
can. it is odd that the class() is kept (which itself an attribute style
structure) and the timezone is lost, but R is full of hand-specified corner
cases.
所以aggregate会把其他多于的attributes丢掉...
很多事情又要重来一次，例如date的格式之类的
总之，此篇作者非常不推荐aggregate
建议大家爱惜自己生命，使用dplyr XDD