Count number of occurences for each unique value

Question

Count number of occurences for each unique value

Let's say I have:

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

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

I want something that gives me

length(v[v==1])

[1] 25

length(v[v==2])

[1] 75

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

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

unique count r-language

3 years ago by Kajalsi45d

2 Answers

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**vishaljlf39** · Answer 1 · 2021-08-06T11:33:55

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

**sandhya6gczb** · Answer 2 · 2021-08-09T06:35:09

If you have multiple factors (= a multi-dimensional data frame), you can use the dplyr package to count unique values in each combination of factors:



library("dplyr")

data %>% group_by(factor1, factor2) %>% summarize(count=n())

It uses the pipe operator %>% to chain method calls on the data frame data.

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Count number of occurences for each unique value

2 Answers

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