按名称删除数据帧列

Question

按名称删除数据帧列

如何使用node.js中的数据发出出站HTTP POST请求？

Answer 1

您可以使用一个简单的名称列表：DF&nbsp;<-&nbsp;data.frame( &nbsp;&nbsp;x=1:10, &nbsp;&nbsp;y=10:1, &nbsp;&nbsp;z=rep(5,10), &nbsp;&nbsp;a=11:20)drops&nbsp;<-&nbsp;c("x","z")DF[&nbsp;,&nbsp;!(names(DF)&nbsp;%in%&nbsp;drops)]或者，您也可以列出要保存的人的列表，并按姓名引用：keeps&nbsp;<-&nbsp;c("y",&nbsp;"a")DF[keeps]编辑：对于那些仍然不熟悉drop参数，如果希望将一列保留为数据框架，则需要：keeps&nbsp;<-&nbsp;"y"DF[&nbsp;,&nbsp;keeps,&nbsp;drop&nbsp;=&nbsp;FALSE]drop=TRUE(或者不提)将删除不必要的维度，从而返回带有列值的向量。y.

Answer 2

还有subset命令，如果您知道需要哪些列，则此命令非常有用：df&nbsp;<-&nbsp;data.frame(a&nbsp;=&nbsp;1:10,&nbsp;b&nbsp;=&nbsp;2:11,&nbsp;c&nbsp;=&nbsp;3:12)df&nbsp;<-&nbsp;subset(df,&nbsp;select&nbsp;=&nbsp;c(a,&nbsp;c))在@Hadley评论后更新：to滴下列a，c您可以这样做：df&nbsp;<-&nbsp;subset(df,&nbsp;select&nbsp;=&nbsp;-c(a,&nbsp;c))

Answer 3

within(df,&nbsp;rm(x))可能是最简单的，或者对于多个变量：within(df,&nbsp;rm(x,&nbsp;y))或者如果你在处理data.tableS(每如何在data.table中按名称删除列？):dt[,&nbsp;x&nbsp;:=&nbsp;NULL]&nbsp;&nbsp;&nbsp;#&nbsp;Deletes&nbsp;column&nbsp;x&nbsp;by&nbsp;reference&nbsp;instantly.dt[,&nbsp;!"x"]&nbsp;&nbsp;&nbsp;#&nbsp;Selects&nbsp;all&nbsp;but&nbsp;x&nbsp;into&nbsp;a&nbsp;new&nbsp;data.table.或用于多变量dt[,&nbsp;c("x","y")&nbsp;:=&nbsp;NULL]dt[,&nbsp;!c("x",&nbsp;"y")]