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How to Use xtabs() in R to Calculate Frequencies

The xtabs() function in R allows you to quickly calculate frequencies for one or more variables.

It uses the following basic syntax:

xtabs(~variable_name, data=data)

where:

• variable_name:Â The variable that youâ€™d like to calculate the frequencies for.
• data:Â The name of the data frame that the variable comes from.

This tutorial shows several examples of how to use this function in practice.

Example 1: Use xtabs() for One-Way Frequencies

The following code shows how to useÂ xtabs() to calculate the frequencies for the variableÂ team:

```#create data frame
df rep(c('A', 'B', 'C'), times=c(27, 33, 40)),
position=rep(c('Guard', 'Forward', 'Center'), times=c(20, 50, 30)),
points=runif(100, 1, 50))

#view first six rows of data frame

team position   points
1    A    Guard 14.00992
2    A    Guard 19.23407
3    A    Guard 29.06981
4    A    Guard 45.50218
5    A    Guard 10.88241
6    A    Guard 45.02109

#calculate frequencies of team variable
xtabs(~team, data=df)

team
A  B  C
27 33 40 ```

From the output we can see that:

• Team A occursÂ 27Â times in the data frame.
• Team A occursÂ 33Â  times in the data frame.
• Team A occursÂ 40 times in the data frame.

Example 2: Use xtabs() for Two-Way Frequencies

The following code shows how to useÂ xtabs() to calculate the two-way frequencies for the variables team andÂ position:

```#create data frame
df rep(c('A', 'B', 'C'), times=c(27, 33, 40)),
position=rep(c('Guard', 'Forward', 'Center'), times=c(20, 50, 30)),
points=runif(100, 1, 50))

#calculate frequencies of team and position variables
xtabs(~team+position, data=df)

position
team Center Forward Guard
A      0       7    20
B      0      33     0
C     30      10     0 ```

From the output we can see that:

• There are 0 Centers on team A.
• There areÂ 7Â Forwards on team A.
• There areÂ 20Â Guards on team A.

And so on.

Using xtabs() for n-Way Frequencies

TheÂ xtabs()Â function can actually be used to calculate frequencies for any number of variables by simply using the following syntax:

`xtabs(~variable1+variable2+variable3+...+variablen, data=df)`

In practice, this function is used most often to calculate one-way and two-way frequencies.