{"id":4220,"date":"2020-03-23T10:51:36","date_gmt":"2020-03-23T10:51:36","guid":{"rendered":"https:\/\/www.askpython.com\/?p=4220"},"modified":"2020-03-23T10:51:37","modified_gmt":"2020-03-23T10:51:37","slug":"average-of-a-list-in-python","status":"publish","type":"post","link":"https:\/\/www.askpython.com\/python\/list\/average-of-a-list-in-python","title":{"rendered":"Find the Average of a List in Python with 5 Easy Methods"},"content":{"rendered":"\n

There are many ways to find the average of a list in Python, provided all of them are of the same type. In this article, we’ll look at some of the methods to find the average element of a Python List<\/a>.<\/p>\n\n\n\n

Let’s get started!<\/p>\n\n\n\n

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Method 1: Use reduce() to find the average of a list in Python<\/h2>\n\n\n\n

We can use the reduce<\/strong>() method, along with a lambda function (As shown here<\/a>).<\/p>\n\n\n\n

We’ll sum up the elements using the lambda, and divide the result by the length of the list since average = (Sum of all elements) \/ (Number of elements)<\/strong><\/p>\n\n\n\n

So, the corresponding expression is:<\/p>\n\n\n

\naverage = (reduce(lambda x, y: x + y, input_list)) \/ len(input_list)\n<\/pre><\/div>\n\n\n
Let’s take a full example, to show this in action.<\/p>\n\n\n
\nfrom functools import reduce\n\ninput_list = [3, 2, 1, 5, 7, 8]\n\naverage = (reduce(lambda x, y: x + y, input_list)) \/ len(input_list)\n\nprint("Average of List:", average)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\nAverage of List: 4.333333333333333\n<\/pre><\/div>\n\n\n
This is indeed the correct output, since the average is: (3 + 2 + 1 + 5 + 7 + 8) \/ 6 = 26 \/ 6 = 4.333<\/strong><\/p>\n\n\n\n
We cannot pass elements of different types, since the +<\/code> operand may not work. So, all the elements of the list must be type compatible with the +<\/code> operand in order for this to work. This is one of the methods we can find the average of a list in Python.<\/p>\n\n\n\n
Method 2: Using the sum() method (Recommended)<\/h2>\n\n\n\n
Instead of using the reduce()<\/code> method, we can directly find the sum using sum(list)<\/code>, and divide it by the length.<\/p>\n\n\n
\ninput_list = [3, 2, 1, 5, 7, 8]\n\naverage = sum(input_list) \/ len(input_list)\n\nprint("Average of List:", average)\n<\/pre><\/div>\n\n\n
We’ll get the same output as before!<\/p>\n\n\n\n
This is the recommended method of finding the average of a list in Python, since it uses only built-in functions, and is really simple to use.<\/p>\n\n\n\n
Method 3: Using statistics.mean()<\/h2>\n\n\n\n
For Python versions of 3.4<\/strong> and above, we can also use the statistics<\/code> module to find the average of a list in Python.<\/p>\n\n\n
\nimport statistics\n\ninput_list = [3, 2, 1, 5, 7, 8]\n\naverage = statistics.mean(input_list)\n\nprint("Average of List:", average)\n<\/pre><\/div>\n\n\n
Method 4: Using numpy.mean()<\/h2>\n\n\n\n
If you want to use NumPy<\/strong> based methods, numpy.mean()<\/code> will do this for you.<\/p>\n\n\n
\nimport numpy as np\n\ninput_list = [3, 2, 1, 5, 7, 8]\n\naverage = np.mean(input_list)\n\nprint("Average of List:", average)\n<\/pre><\/div>\n\n\n
You can also convert the list into a numpy array<\/strong>, and then get the mean using ndarray.mean<\/code>. You can use whichever is better for your use-case, but they perform about the same.<\/p>\n\n\n
\nimport numpy as np\n\ninput_list = [3, 2, 1, 5, 7, 8]\n\n# Convert to a numpy ndarray and get the mean\n# using ndarray.mean\naverage = np.array(input_list).mean\n\nprint("Average of List:", average)\n<\/pre><\/div>\n\n\n
Method 5: Using pandas Series.mean()<\/h2>\n\n\n\n
If you’re using Pandas<\/code>, you can get the mean of a list using pandas.Series(list).mean()<\/code><\/p>\n\n\n
\nimport pandas as pd\n\ninput_list = [3, 2, 1, 5, 7, 8]\n\n# Convert the list to a Pandas Series using pd.Series(list)\n# and then get it's mean using series.mean()\naverage = pd.Series(input_list).mean()\n\nprint("Average of List:", average)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\nAverage of List: 4.333333333333333\n<\/pre><\/div>\n\n\n
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Conclusion<\/h2>\n\n\n\n
In this article, we learned how we could find the average of a list in Python, using different approaches.<\/p>\n\n\n\n
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References<\/h2>\n\n\n\n