# How to Use mean Function in R (With Examples)

You can use the mean() function in R to calculate the mean of values in a vector:

```mean(x)
```

The following examples show how to use this function in practice.

### Example 1: Calculate Mean of Vector

The following code shows how to calculate the mean value of a vector in R:

```#define vector
x <- c(3, 6, 7, 7, 12, 14, 19, 22, 24)

#calculate mean of vector
mean(x)

[1] 12.66667
```

If your vector has missing values, be sure to specify na.rm = TRUE to ignore missing values when calculating the mean:

```#define vector with some missing values
x <- c(3, 6, 7, 7, NA, 14, NA, 22, 24)

#calculate mean of vector
mean(x, na.rm = TRUE)

[1] 11.85714
```

You can also use the trim argument to trim a certain fraction (0 to 0.5) of observations from each end of a vector before calculating the mean:

```#define vector
x <- c(3, 6, 7, 7, 12, 14, 19, 22, 24)

#calculate mean of vector after trimming 20% of observations off each end
mean(x, trim = 0.2)

[1] 12.42857
```

### Example 2: Calculate Mean of Column in Data Frame

The following code shows how to calculate the mean value of a certain column in a data frame:

```#define data frame
df <- data.frame(a=c(3, 6, 7, 7, 12, 14, 19, 22, 24),
b=c(4, 4, 5, 12, 13, 14, 9, 1, 2),
c=c(5, 6, 6, 3, 5, 5, 6, 19, 25))

#calculate mean of column 'a'
mean(df\$a)

[1] 12.66667
```

### Example 3: Calculate Mean of Several Columns in Data Frame

The following code shows how to use the apply() function to calculate the mean of several columns in a data frame:

```#define data frame
df <- data.frame(a=c(3, 6, 7, 7, 12, 14, 19, 22, 24),
b=c(4, 4, 5, 12, 13, 14, 9, 1, 2),
c=c(5, 6, 6, 3, 5, 5, 6, 19, 25))

#calculate mean of columns 'a' and 'c'
apply(df[ , c('a', 'c')], 2, mean)

a         c
12.666667  8.888889```