数据框中所有列的唯一值计数

Question

我们有一个数据框如下:

raw<-data.frame(v1=c("A","B","C","D"),v2=c(NA,"B","C","A"),v3=c(NA,"A",NA,"D"),v4=c(NA,"D",NA,NA))

我需要以下格式的结果数据框:

result<-data.frame(v1=c("A","B","C","D"), v2=c(3,2,2,3))

使用以下代码获取一个特定列的计数:

count_raw<-sqldf("SELECT DISTINCT(v1) AS V1, COUNT(v1) AS count FROM raw GROUP BY v1")

这将返回单个列中唯一值的计数.

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Answer 1

用这个

table(unlist(raw))

产量

A B C D 
3 2 2 3 

对于数据帧类型输出包装 as.data.frame.table

as.data.frame.table(table(unlist(raw)))

产量

   Var1 Freq
1    A    3
2    B    2
3    C    2
4    D    3