r - 计算相同行数

Question

我希望这不是一个重复的问题(尽我所能,看看它是否已被问到).我有一个数据框,想要计算有多少行相同.

df = data.frame(ID = c("id1", "id2", "id3", "id4", "id5", "id6", "id7", "id8", "id9"),
            Val1 = c("A", "B", "C", "A", "A", "B", "D", "C", "D"),
            Val2 = c("B", "C", NA, "B", "B", "D", "E", "D", "E"),
            Val3 = c("C", NA, NA, "C", "C", "B", NA, NA,NA),
            Val4 = c("D", NA, NA, "E", "D", NA, NA, NA, NA))
> df
   ID Val1 Val2 Val3 Val4
1 id1    A    B    C    D
2 id2    B    C <NA> <NA>
3 id3    C <NA> <NA> <NA>
4 id4    A    B    C    E
5 id5    A    B    C    D
6 id6    B    D    B <NA>
7 id7    D    E <NA> <NA>
8 id8    C    D <NA> <NA>
9 id9    D    E <NA> <NA>

所以,在这个例子中我期望的回报是A B C D 2,D E 2,B C <NA> <NA> 1等..试过table,但我得到了Error in table(type_table) : attempt to make a table with >= 2^31 elements我的DF的"唯一"〜140K行.我想在更大的数据集上应用它.尝试summarise也可能但我可能不知道如何正确应用它.是aggregate一种选择吗？谢谢

Answer 1

之所以table不起作用是因为它分别处理每个列并尝试按元素组合而不是按行组合查找.

您可以尝试使用该do.call(paste(组合,以便按行粘贴元素并table在其上运行

table(do.call(paste, df[-1]))
# A B C D    A B C E  B C NA NA   B D B NA  C D NA NA C NA NA NA  D E NA NA 
#       2          1          1          1          1          1          2 

如果table没有足够的效率,我们可以尝试.N从data.table替代

library(data.table) 
setDT(df)[, .N, by = c(names(df)[-1])]
#    Val1 Val2 Val3 Val4 N
# 1:    A    B    C    D 2
# 2:    B    C   NA   NA 1
# 3:    C   NA   NA   NA 1
# 4:    A    B    C    E 1
# 5:    B    D    B   NA 1
# 6:    D    E   NA   NA 2
# 7:    C    D   NA   NA 1