[關鍵字]:
do not use aggregate
[出處]:
http://www.r-bloggers.com/dont-use-statsaggregate/
[重點摘要]:
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會把其他多於的attributes丟掉...
很多事情又要重來一次，例如date的格式之類的
總之，此篇作者非常不推薦aggregate
建議大家愛惜自己生命，使用dplyr XDD