计算R中的唯一值 [英] Count unique values in R

问题描述

假设我有

v = rep(c(1,2, 2, 2), 25)

现在，我想计算每个唯一值的出现次数。 unique（v）返回唯一值是什么，但不返回它们的数量。

Now, I want to count the number of times each unique value appears. unique(v) returns what the unique values are, but not how many they are.

> unique(v)
[1] 1 2

p>

I want something that gives me

length(v[v==1])
[1] 25
length(v[v==2])
[1] 75

）这样接近（但不完全）：

but as a more general one-liner :) Something close (but not quite) like this:

#<doesn't work right> length(v[v==unique(v)])

推荐答案

p>也许表是你以后的？

Perhaps table is what you are after?

dummyData = rep(c(1,2, 2, 2), 25)

table(dummyData)
# dummyData
#  1  2 
# 25 75

## or another presentation of the same data
as.data.frame(table(dummyData))
#    dummyData Freq
#  1         1   25
#  2         2   75

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