如何使用单个值删除数据框列 [英] How to remove data frame column with a single value

问题描述

假设我在R中具有以下数据帧：

Let say I have the following data frame in R:

df1 <- data.frame(Item_Name = c("test1","test2","test3"), D_1=c(1,0,1),
                  D_2=c(1,1,1), D_3=c(11,3,1))

我想创建一个函数来删除无差异的列
（例如在这种情况下，它将删除列 D_2 ，因为它只有1个值）

I would like to create a function that would delete columns with no variance (e.g. in this case, it would remove column D_2 because it has only 1 value)

我知道我可以检查它手动，但实际上我的数据非常大，我想实现自动化。知道吗？

I know that I could check it by hand, but in reality my data is very large and I would like to automate it. Any idea?

推荐答案

过滤器在这里是有用的功能。我将仅过滤那些唯一值超过1的对象。

Filter is a useful function here. I will filter only for those where there is more than 1 unique value.

ie

Filter(function(x)(length(unique(x))>1), df1)

##   Item_Name D_1 D_3
## 1     test1   1  11
## 2     test2   0   3
## 3     test3   1   1

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