📘 Computing the average value of an array using Perl 6

Find the average value of the given array of numbers.

Calculating the average value of an array has two subtasks—calculate the sum and divide it by the size of the array. So, one of the solutions can look like this:

my @data = 7, 11, 34, 50, 200;
say sum(@data) / @data;

Here, the sum built-in function returns the sum of the elements of the @data array. To get the size of an array, you may call the elems method:

say sum(@data) / @data.elems;

This is a straightforward way, which is a bit redundant for our task. As the @data is used in numeric context as an operand of the division operator, explicitly calling the elems method is not necessary.

Another approach is to use the reduction operator:

say ([+] @data) / @data;

In this example, [+] @data is equivalent to @data[0] + @data[1] + ...+ @data[N], where the + operator is placed between all the elements of the array. Be careful with the parentheses in this code. If you omit them, the result will be incorrect, as the actual sum consists of a single element @data / @data, which equals one. If you omit the space before the opening brace, it will be considered as a parenthesis grouping the arguments of the sayfunction, and the result is also incorrect, as the code prints only the sum of the array elements and divides the result of say (which is 1).

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