我在 R 中有以下数据框:
c1 c2
1 10 a
2 20 a
3 30 b
4 40 b
我然后split
它如下z = lapply(split(test$c1, test$c2), function(x) {cut(x,2)})
: z
然后是:
$a
[1] (9.99,15] (15,20]
Levels: (9.99,15] (15,20]
$b
[1] (30,35] (35,40]
Levels: (30,35] (35,40]
然后我想通过取消拆分列表来合并这些因素unsplit(z, test$c2)
。这会产生一个警告:
[1] (9.99,15] (15,20] <NA> <NA>
Levels: (9.99,15] (15,20]
Warning message:
In `[<-.factor`(`*tmp*`, i, value = 1:2) :
invalid factor level, NAs generated
我想将所有因子级别合并,然后取消拆分,以免发生此错误:
z$a = factor(z$a, levels=c(levels(z$a), levels(z$b)))
unsplit(z, test$c2)
[1] (9.99,15] (15,20] (30,35] (35,40]
Levels: (9.99,15] (15,20] (30,35] (35,40]
在我的真实数据框中,我有一个非常大的列表,所以我需要遍历所有列表元素(不仅仅是两个)。做这个的最好方式是什么?