计算每行唯一值的数量 [英] Count number of unique values per row

问题描述

我想计算每行唯一值的数量.

I want to count the number of unique values per row.

例如使用这个数据框:

example <- data.frame(var1 = c(2,3,3,2,4,5), 
                  var2 = c(2,3,5,4,2,5), 
                  var3 = c(3,3,4,3,4,5))

我想添加一个列来计算每行唯一值的数量；例如第一行是 2(因为第一行有 2 和 3)，第二行是 1(因为第二行只有 3).

I want to add a column which counts the number of unique values per row; e.g. 2 for the first row (as there are 2's and 3's in the first row) and 1 for the second row (as there are only 3's in the second row).

有谁知道一个简单的代码来做到这一点?到目前为止，我只找到了计算每列唯一值数量的代码.

Does anyone know an easy code to do this? Up until now I only found code for counting the number of unique values per column.

推荐答案

这个 apply 函数返回一个表示每行唯一值个数的向量:

This apply function returns a vector of the number of unique values in each row:

apply(example, 1, function(x)length(unique(x)))

您可以使用以下两种方式之一将其附加到您的 data.frame 中(如果您想将该列命名为 count):

You can append it to your data.frame using on of the following two ways (and if you want to name that column as count):

example <- cbind(example, count = apply(example, 1, function(x)length(unique(x))))

或

example$count <- apply(example, 1, function(x)length(unique(x)))

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