Question

Write a function def repeat(string, \(n\), delin) that returns the string string repeated n times, separated by the string delin. For example, repest \(\left(\right.\) "ho \(^{*}, 3,^{\circ}\), ") returns "ho, to, ho".

Short answer

Define a function using `delin.join(string for _ in range(n))` to repeat and separate.

Step-by-step solution

Define the Function Structure

Start by defining the function named `repeat` with parameters `string`, `n`, and `delin`. This sets up the basic structure of the function we will work with.

Create the Result String

Within the function, use the `join` method combined with a generator expression. The generator repeats `string` for `n` times and joins these repetitions with the separator `delin`. This can be written as `result = delin.join(string for _ in range(n))`.

Return the Result

After creating the result by joining with the separator, return the result string from the function. This returned value is what the function outputs when called.

Key concepts

Function Parameters

In Python, function parameters are the variables listed inside the parentheses in the function definition. They serve as placeholders for the values that are passed to the function when it is called. This allows functions to operate on different data inputs without needing to rewrite the code for each input. In the example function `repeat(string, n, delin)`, there are three parameters:

• `string`: The text you want to repeat.
• `n`: The number of times the string should be repeated.
• `delin`: The delimiter used to separate each repetition of the string.

These parameters enable the function to be versatile and work with different strings, repetition counts, and delimiters.

Join Method

The `join` method is a string method in Python that is used for concatenating the elements of an iterable (such as a list or tuple) into a single string, with each element separated by the string on which `join` is called. It is quite efficient and convenient for building strings when you have a series of substrings that need a common separator.
For instance, in our function, `delin.join(string for _ in range(n))` is used. Here, `delin` is the separator, and the iterable is generated by the generator expression `(string for _ in range(n))`, producing `n` repetitions of `string`. This method saves us from manually handling concatenation and ensures the separators are correctly placed.
Using `join` is preferred over using concatenation operators like `+` in loops, especially when dealing with larger numbers of elements, due to performance benefits.

String Repetition

String repetition involves creating a new string by repeating a given string multiple times. In Python, this can be done using the `*` operator or more dynamically using loops or comprehensions. In the context of our function, string repetition is handled through a generator expression.
Within the function, the idea is to repeat `string` exactly `n` times. This is efficiently achieved by using a generator expression `string for _ in range(n)` within the `join` method. Each loop iteration produces another copy of the `string`, and these copies are then concatenated with the specified delimiter `delin`.
String repetition is useful in cases where you need to automate or dynamically define repeated patterns within strings.

Generator Expression

Generator expressions provide a compact way to generate iterators quickly and succinctly. They are similar to list comprehensions but do not store the entire list in memory. Instead, they generate items one by one, which is more memory efficient, especially for large data sets.
In the function `repeat`, the generator expression `string for _ in range(n)` is employed. This expression iterates `n` times, each time yielding the `string`. The `join` method then processes these generated strings. Since the generator does not store elements, it is beneficial when dealing with a substantial number of repetitions, making the operations lighter on memory usage.
Generators are crucial for improving performance in scenarios where the entire data set isn't needed to be stored all at once.