关于使用R满足条件的计数列

Question

我们如何计算满足某些条件的列数。

df <- data.frame(id=c(1,2,3,4),v1=c(0.2,0.4,0.6,0.9),
       v2=c(0.1,0.2,0.6,0.1),v3=c(0.1,0.4,0.6,0.1))  


count<-function(x){dplyr::count(x>=0.5)}
df$count<-apply(x = df[,c(2:4)], MARGIN = 1, FUN =count, na.rm = TRUE)

这不起作用.....

应该是

df$count<-c(0,0,3,1)

Answer 1

您可以使用rowSums来计算df[-1]>=0.5的条件：

rowSums(df[-1]>=0.5)
#[1] 0 0 3 1

Answer 2

带有Reduce

的选项

Reduce(`+`, lapply(df[-1], `>=`, 0.5))
#[1] 0 0 3 1