# 5 Ways to Find The Average of a List in Python

Filed Under: Python

Hi Folks! In this article, we will have a look at the various ways to find the average of a list in a Python List.

In general, an average is a value that represents a whole set of data items or elements.

Formula: Average = summation of numbers/total count.

## Techniques to find the average of a list in Python

Either of the following techniques can be used to calculate the average/mean of a list in Python:

• Python mean() function
• In-built sum() method
• Python lambda and reduce() method

### 1. Python mean() function

Python 3 has `statistics module` which contains an in-built function to calculate the mean or average of numbers. The `statistics.mean() function` is used to calculate the mean/average of input values or data set.

The mean() function accepts the list, tuple or data-set containing numeric values as a parameter and returns the average of the data-items.

Syntax:

```mean(data-set/input-values)
```

Example:

```from statistics import mean

inp_lst = [12, 45, 78, 36, 45, 237.11, -1, 88]
list_avg = mean(inp_lst)

print("Average value of the list:\n")
print(list_avg)
print("Average value of the list with precision upto 3 decimal value:\n")
print(round(list_avg,3))

```

In the above snippet of code, we have used `statistics.round()` method to round off the output average up to a particular decimal value.

Syntax:

```statistics.round(value, precision value)
```

Output:

```Average value of the list:

67.51375
Average value of the list with precision upto 3 decimal value:

67.514
```

### 2. Using Python sum() function

Python `statistics.sum()`function can also be used to find the average of data values in Python list.

The `statistics.len()` function is used to calculate the length of the list i.e. the count of data items present in the list.

Syntax:

```len(input-list)
```

Further, `statistics.sum()` function is used to calculate the sum of all the data items in the list.

Syntax:

```sum(input-list)
```

Note: average = (sum)/(count).

Example:

```from statistics import mean

inp_lst = [12, 45, 78, 36, 45, 237.11, -1, 88]

sum_lst = sum(inp_lst)

lst_avg = sum_lst/len(inp_lst)
print("Average value of the list:\n")
print(lst_avg)
print("Average value of the list with precision upto 3 decimal value:\n")
print(round(lst_avg,3))
```

Output:

```Average value of the list:

67.51375
Average value of the list with precision upto 3 decimal value:

67.514

```

### 3. Using Python reduce() and lambda method

We can use Python reduce() function along with the lambda() function.

Python reduce() function: The `reduce() function` is basically used to apply a particular(input) function to the set of elements passed to the function.

Syntax:

```reduce(function,input-list/sequence)
```
• Initially, the reduce() function applies the passed function to the first two consecutive elements and returns the result.
• Further, we apply the same function to the result obtained in the previous step and the element succeeding the second element.
• This process continues until it reaches the end of the list.
• Finally, the result is returned to the terminal/screen as output.

Python lambda() function: The `lambda() function` is used to build and form Anonymous functions i.e. function without a name or signature.

Syntax:

```lambda arguments:function
```

Example:

```from functools import reduce

inp_lst = [12, 45, 78, 36, 45, 237.11, -1, 88]

lst_len= len(inp_lst)

lst_avg = reduce(lambda x, y: x + y, inp_lst) /lst_len
print("Average value of the list:\n")
print(lst_avg)
print("Average value of the list with precision upto 3 decimal value:\n")
print(round(lst_avg,3))

```

Output:

```Average value of the list:

67.51375
Average value of the list with precision upto 3 decimal value:

67.514

```

### 4. Python operator.add() function to find the average of a list

The Python operator module contains various functions to perform basic calculations and operations efficiently.

The `operator.add()` function can be used to calculate the summation of all the data values present in the list with the help of Python reduce() function.

Syntax:

```operator.add(value1, value2)
```

Note: average = (sum)/(length or count of elements)

Example:

```from functools import reduce
import operator
inp_lst = [12, 45, 78, 36, 45, 237.11, -1, 88]

lst_len = len(inp_lst)

print("Average value of the list:\n")
print(lst_avg)
print("Average value of the list with precision upto 3 decimal value:\n")
print(round(lst_avg,3))
```

Output:

```Average value of the list:

67.51375
Average value of the list with precision upto 3 decimal value:

67.514
```

### 5. NumPy average() method to calculate the average of a list in Python

Python’s NumPy module has an in-built function to calculate the average/mean of the data items present in the data set or list.

The `numpy.average()` method is used to calculate the average of the input list.

Example:

```import numpy

inp_lst = [12, 45, 78, 36, 45, 237.11, -1, 88]

lst_avg = numpy.average(inp_lst)
print("Average value of the list:\n")
print(lst_avg)
print("Average value of the list with precision upto 3 decimal value:\n")
print(round(lst_avg,3))

```

Output:

```Average value of the list:

67.51375
Average value of the list with precision upto 3 decimal value:

67.514
```

## Conclusion

Thus, in this article, we have unveiled and understood various techniques to find the average of a Python List.

## References

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