How to count multiple numerical variables in a column in R without installing a package?

Question

I'd like to count the number of recurring numerical variables in a given column. My data set is: mydata

And I have a dataframe that looks like this:

mydata <- structure(list(VARIABLE = c(1, 1, 2, 3, 3, 3, 4, 4)), 
  .Names = "VARIABLE",   row.names = c(NA, -8L), class = "data.frame")

mydata
##     VARIABLE
## 1        1
## 2        1
## 3        2
## 4        3
## 5        3
## 6        3
## 7        4
## 8        4

I'd like to calculate the number of 1s,2s,3s,4s in column VARIABLE (Two 1, One 2, Three 3, Two 4). Is there anyway I can do this without installing an additional package?

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okay! thank you!! I'll learn how to ask question in a proper format! — Pirate, Sep 11 '12 at 01:52

flodel · Accepted Answer · 2012-09-11T02:14:21.570

4

Yes, use table as follows, it comes from the base package:

mydata <- data.frame(VARIABLE = c(1, 1, 2, 3, 3, 3, 4, 4))
table(mydata$VARIABLE)

# 1 2 3 4 
# 2 1 3 2

As suggested by Maiasaura, you can turn the output into a nice data.frame:

data.frame(table(mydata$VARIABLE))
#   Var1 Freq
# 1    1    2
# 2    2    1
# 3    3    3
# 4    4    2

edited Sep 11 '12 at 02:14

answered Sep 11 '12 at 01:48

flodel

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1

`data.frame(table(VARIABLE))` would result in nicer formatting. – Maiasaura Sep 11 '12 at 02:09

score 0 · Answer 2 · answered Sep 11 '12 at 02:13

As an alternative to ?table you could also use ?rle in the instance of wanting to detect "runs" of particular repeating values in a variable/vector. In this instance, you will get the same results as using the table function, though this is not always the case.

mydata <- data.frame(VARIABLE = c(1, 1, 2, 3, 3, 3, 4, 4))
rle(mydata$VARIABLE)

Result:

Run Length Encoding
  lengths: int [1:4] 2 1 3 2
  values : num [1:4] 1 2 3 4

You can subset the results of the rle function as well, like so:

rle(mydata$VARIABLE)$values
[1] 1 2 3 4

rle(mydata$VARIABLE)$lengths
[1] 2 1 3 2

You can create a `data.frame` from the results by `do.call(data.frame,rle(mydata$VARIABLE))` — mnel, Sep 11 '12 at 02:21

How to count multiple numerical variables in a column in R without installing a package?

2 Answers2