The drop argument in dcast (from "reshape2" or "dplyr") can be useful when going from a "long" to a "wide" dataset and you want to create columns even for combinations that do not exist in the long form. (from "reshape2" or
阅读背景：
在“dcast”中，只查看公式的RHS，就可以进行“drop”参数。
来源：互联网
分享到：
