# Python mean: How to Calculate Average in Python

**Python 3** provides the **statistics** module, which comes with very useful functions like **mean()**, median(), mode(), etc. The arithmetic mean is a sum of data that is divided by the number of data points. It measures the central location of data in a set of values that vary in range.

**Python mean**

The mean() is a built-in Python statistics module function used to calculate the average of numbers and lists. The mean() returns the mean of the data set passed as parameters.

To use the mean() method in the Python program, import the Python statistics module, and then we can use the mean function to return the mean of the given list. See the following example.

The Statistics module provides functions for calculating mathematical statistics of numeric (Real-valued) data. Let’s see some examples of the Statistics module.

# app.py import statistics data = [11, 21, 11, 19, 46, 21, 19, 29, 21, 18, 3, 11, 11] x = statistics.mean(data) print(x) y = statistics.median(data) print(y) z = statistics.mode(data) print(z) a = statistics.stdev(data) print(a) b = statistics.variance(data) print(b)

See the following output.

➜ pyt python3 app.py 18.53846153846154 19 11 10.611435534486562 112.6025641025641 ➜ pyt

In the above code example, we have used Mean, mode, median, variance, stddev functions.

**Python average of a list**

To calculate a mean or average of the list in Python,

- Using statistics.mean() function.
- Use the sum() and len() functions.
- Using Python numpy.mean().

The formula to calculate the average is achieved by calculating the sum of the numbers in the list divided by a count of numbers in the list.

# app.py import statistics spiList = [5.55, 5.72, 7.3, 7.75, 8.4, 9, 8.8, 8.2] print(statistics.mean(spiList))

See the following output.

In the above example, we have eight data points and using statistics.mean() function, we calculated the mean of the list.

**Using For loop to calculate the mean**

In the following code example, we have initialized the variable sumOfNumbers to 0 and used a for loop. Python for loop will loop through the elements present in the list, and each number is added and saved inside the sumOfNumbers variable.

The average is calculated using the sumOfNumbers divided by the count of the numbers in the list using the len() built-in function.

See the following code.

# app.py def averageOfList(num): sumOfNumbers = 0 for t in num: sumOfNumbers = sumOfNumbers + t avg = sumOfNumbers / len(num) return avg print("The average of List is", averageOfList([19, 21, 46, 11, 18]))

**Output**

python3 app.py The average of List is 23.0

In the above code, we are using for loop to the sum of all items and then divide that sum by several items to get the average of the list in Python.

**Using sum() and len() functions**

Python sum() is a built-in function that returns the sum of all list elements. Python len() function gives the number of items in the list. We will use the combination of these two inbuilt functions to get the mean of the list.

See the following code.

# app.py def averageOfList(numOfList): avg = sum(numOfList) / len(numOfList) return avg print("The average of List is", round(averageOfList([19, 21, 46, 11, 18]), 2))

**Output**

python3 app.py The average of List is 23.0

**Using numpy.mean() function**

NumPy.mean() function returns the average of the array elements. The average is taken over the flattened array by default, otherwise over the specified axis.

Numpy library is a commonly used library to work on large multi-dimensional arrays. It also has an extensive collection of mathematical functions to be used on arrays to perform various tasks. One important thing to note here is that the mean() function will give us the average for the list given.

See the below code.

# app.py from numpy import mean number_list = [19, 21, 46, 11, 18] avg = mean(number_list) print("The average of List is ", round(avg, 2))

**Output**

python3 app.py The average of List is 23.0

**More Examples**

First, we will import the statistics module and then call the mean() function to get the mean of data.

# app.py import statistics data = [21, 19, 18, 46, 30] print(statistics.mean(data))

See the below output.

**Calculate the Mean of a tuple in Python.**

To find the mean of a tuple in Python, use the statistics.mean() method is the same as we find the mean of the list. We have to pass the tuple as a parameter. Let’s calculate the mean of the tuple using the following code.

# app.py import statistics tupleA = (1, 9, 2, 1, 1, 8) print(statistics.mean(tupleA))

The output of the above code is following.

It will work the same as a list. It merely returns the **Mean **of the numbers inside the **tuple.**

**Calculating the Mean of Dictionary in Python**

To calculate the mean of Dictionary, we can use the statistics.mean() method. In Dictionary, the mean function only counts the keys as numbers and returns the mean of that Dictionary based on the dictionary keys.

# app.py import statistics dictA = {1: 19, 2:21, 3:18, 4:46, 5:30} print(statistics.mean(dictA))

See the below output.

**Calculating a mean of a tuple of a negative set of integers**

To find the mean of a tuple of the negative set, we use statistics.mean() method. We need to pass the negative tuple as a parameter to the mean() function, and in return, we will get the output.

Let’s see the tuple of negative integers.

# app.py import statistics data = (-11, -21, -18, -19, -46) print(statistics.mean(data))

See the following output.

➜ pyt python3 app.py -23 ➜ pyt

Let’s take an example of the tuple of a mixed range of numbers.

# app.py import statistics data = (11, 21, -18, 19, -46) print(statistics.mean(data))

See the following output.

➜ pyt python3 app.py -2.6 ➜ pyt

**Calculate the mean of a list of a negative set of integers**

To calculate the mean of the list in Python, use the statistics.mean() method. We will pass the list of the negative set to the mean() method, and in the output, we will calculate the mean.

Let’s take a list of negative sets of integers and apply the **mean() function**.

# app.py import statistics data = [-11, -21, -18, -19, -46] print(statistics.mean(data))

See the following output.

➜ pyt python3 app.py -23 ➜ pyt

Let’s take an example of the list of a mixed range of numbers.

# app.py import statistics data = [11, 21, -18, -19, 46] print(statistics.mean(data))

See the output.

➜ pyt python3 app.py 8.2 ➜ pyt

**How To Calculate the mean of the list of fractions**

To calculate the mean of the list of fractions, use statistics.mean() method. First, we have to import the statistics and fractions module and then create a fraction of numbers, and in the output, we will get the mean values.

# app.py import statistics from fractions import Fraction as fr data = [fr(1, 2), fr(44, 12), fr(10, 3), fr(2, 3)] print(statistics.mean(data))

See the following output.

➜ pyt python3 app.py 49/24 ➜ pyt

**TypeError in Python**

Let’s take string keys in the Python dictionary and get the mean of the string values. It will get the error because we can not find the string’s mean value.

See the following code.

# app.py import statistics data = {"a": 11, "b": 21, "c": 19, "d": 29, "e": 18, "f": 46} print(statistics.mean(data))

See the following output.

➜ pyt python3 app.py Traceback (most recent call last): File "app.py", line 6, in print(statistics.mean(data)) File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/statistics.py", line 312, in mean T, total, count = _sum(data) File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/statistics.py", line 148, in _sum for n,d in map(_exact_ratio, values): File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/statistics.py", line 230, in _exact_ratio raise TypeError(msg.format(type(x).__name__)) TypeError: can't convert type 'str' to numerator/denominator ➜ pyt

**Conclusion**

To find the average or mean of List in Python, we can use the following ways.

- Using the statistics.mean() method.
- Using Python sum() and len() method.
- Using Numpy.mean() function.
- Using Python for loop and len() method.

Finally, Python mean() Function Example is over.

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