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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