# How to Calculate Log in R (With Examples)

You can use the log() function in R to calculate the log of some value with a specified base:

```#calculate log of 9 with base 3
log(9, base=3)
```

If you don’t specify a base, R will use the default base value of e.

```#calculate log of 9 with base e
log(9)

 2.197225
```

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

### Example 1: Calculate Log of Single Value

The following code shows how to calculate the log of individual values in R using different bases:

```#calculate log of 100 with base e
log(100)

 4.60517

#calculate log of 100 with base 10
log(100, base=10)

 2

#calculate log of 100 with base 3
log(100, base=3)

 4.191807
```

### Example 2: Calculate Log of Values in Vector

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

```#define vector
x <- c(3, 6, 12, 16, 28, 45)

#calculate log of each value in vector with base e
log(x)

 1.098612 1.791759 2.484907 2.772589 3.332205 3.806662
```

### Example 3: Calculate Log of Values in Data Frame

The following code shows how to calculate the log of values in a specific column of a data frame in R:

```#define data frame
df <- data.frame(var1=c(1, 3, 3, 4, 5),
var2=c(7, 7, 8, 3, 2),
var3=c(3, 3, 6, 6, 8),
var4=c(1, 1, 2, 8, 9))

#calculate log of each value in 'var1' column
log(df\$var1, base=10)

 0.0000000 0.4771213 0.4771213 0.6020600 0.6989700
```

And the following code shows how to use the sapply() function calculate the log of values in every column of a data frame:

```#define data frame
df <- data.frame(var1=c(1, 3, 3, 4, 5),
var2=c(7, 7, 8, 3, 2),
var3=c(3, 3, 6, 6, 8),
var4=c(1, 1, 2, 8, 9))

#calculate log of values in every column
sapply(df, function(x) log(x, base=10))

var1      var2      var3      var4
[1,] 0.0000000 0.8450980 0.4771213 0.0000000
[2,] 0.4771213 0.8450980 0.4771213 0.0000000
[3,] 0.4771213 0.9030900 0.7781513 0.3010300
[4,] 0.6020600 0.4771213 0.7781513 0.9030900
[5,] 0.6989700 0.3010300 0.9030900 0.9542425
```