r - 按一列中的因子拆分/子集数据框

Question

这个问题在这里已经有了答案:





Split data.frame based on levels of a factor into new data.frames

(2 个回答)


4年前关闭。




我的数据是这样的(例如):

ID  Rate    State
1   24  AL
2   35  MN
3   46  FL
4   34  AL
5   78  MN
6   99  FL

数据:

structure(list(ID = 1:6, Rate = c(24L, 35L, 46L, 34L, 78L, 99L),
               State = structure(c(1L, 3L, 2L, 1L, 3L, 2L),
                                 .Label = c("AL","FL", "MN"),
                                 class = "factor")),
          .Names = c("ID", "Rate", "State"),
          class = "data.frame", row.names = c(NA, -6L))

我想按州拆分数据，我想获得 3 个数据集，如下所示:

data set 1
ID  Rate    State
1   24  AL
4   34  AL
data set 2
ID  Rate    State
2   35  MN
5   78  MN
data set 3
ID  Rate    State
3   46  FL
6   99  FL

我应该使用什么功能？

我正在考虑拆分或子集功能，但仍然没有任何线索。

Answer 1

我们可以使用 split :

mylist <- split(df, df$State)

mylist
$AL
  ID Rate State
1  1   24    AL
4  4   34    AL

$FL
  ID Rate State
3  3   46    FL
6  6   99    FL

$MN
  ID Rate State
2  2   35    MN
5  5   78    MN

要访问元素编号:

mylist[[1]]

或按名称:

mylist$AL
  ID Rate State
1  1   24    AL
4  4   34    AL

?split

Description

split divides the data in the vector x into the groups defined by f. The replacement forms replace values corresponding to such a division. unsplit reverses the effect of split.