计算R中的值的频率

Question

我有一个数据框如下

   DATA <- read.table(text = "col1  col2
   ATG   AT
   NA    AT1
   ATC   AT2
   ATD   AT3
   ATE   AT3
   ATF   AT4
   ATH   AT4
   ATI   AT4
   ATL   AT4", header=TRUE)

我用过

   result<-data.frame(table(DATA$col2))

得到我想要的东西

  ##result
  col1  col2
  1     AT
  1     AT1
  1     AT2
  2     AT3
  4     AT4

问题是col1中的第二行有NA，应该算作零，但我无法做到。它应该是

       ##result
  col1  col2
  1     AT
  0     AT1
  1     AT2
  2     AT3
  4     AT4

Answer 1

dfs = read.table(text =
"col1 col2
ATG AT
NA AT1
ATC AT2
ATD AT3
ATE AT3
ATF AT4
ATH AT4
ATI AT4
ATL AT4", sep = " ", header = TRUE)

data.frame(xtabs( !is.na(col1) ~ col2, data = dfs))

Answer 2

如何稍微更改代码：

.hidden-md-up