Python how to repeat

How to Repeat N Times in Python

In Python, “N” times repetition means that any value repeats itself several times in a sequence. There is always a need for repetition in code, like transmitting a message signal in a noisy channel or observing output for testing.

This article provides a detailed understanding of the following concepts regarding N Times repetition in Python:

Let’s get started with the first one:

Method 1: Using the range() function

The “range()” function using “for loop” is the most common and simple way to repeat “N” times in Python. The syntax of the range() function is shown below:

The range function takes three parameters which are described as follows:

• Start parameter represents the value of starting a number of the sequence (it is “0” by default).
• Stop parameter stop at the position which is not included.
• Step parameter represents the value of a sequence’s step size (it is “1” by default).

Let’s understand it with an example of code:

for number in range(7): print(number)

In the above code, the “range()” function takes the number as a parameter which sets the limit (7) of the range function. As the starting value of the “range()” function is not defined, it will start from “0” by default.

The output shows that the sequence of values is printed “N” times (Where N=7).

Method 2: Multiply a String WIth a Number

This is the simplest and most commonly practiced method to repeat a variable “N” times. In this method, the variable is multiplied with a number, and the multiplication result is printed to get the repetitive numbers. The “split() function” is also used along with multiplication to store the elements of string as a list. The use of the “split()” function is optional it is not necessary for the repetition of “N” Times..

Let’s understand it with an example of code.

#repeat N times using split() function value_1 = input('Enter a String you want to repeat = ') value_2 = int(input('Enter a number = ')) strg_1 = value_1*value_2 strg_2 = strg_1.split() result=(strg_2) print('The repeated string is = ',result)

• The string value is initialized in a variable named “value_1”.
• The input number is saved in a variable named “value_2”. Both variables’ values are taken from the user at run time.
• After that, the two variables are multiplied, and a new variable named “strg_1” is used to store the new value.
• The “split()” function converts the string into a list. This conversion is not necessary. However, it helps in processing the data more easily.

The output shows that the value “Ha” is repeated “5” times in a row.

Method 3: Using itertools.repeat() Method

In Python, the built-in method “itertools.repeat()” is used to repeat any string value infinite times until the break value is applied. This function has two parameters, “value” and “num”. The “value” represents the input string and the “num” value represents the number of times the value repeated itself. Using this module, any string value repeats “N” times in Python.

Let’s understand the concept of the “itertools.repeat()” function with an example:

#using itertools module import itertools list_1 = list(itertools.repeat('Hello', 3)) print(list_1)

• The “itertools” module is imported in code.
• The “itertools.repeat(value, num)” function takes two parameters inside the parenthesis. The value and number are provided in the parameter to repeat the “Hello” “3” times.

The output shows that the string “Hello” is repeated “3” times.

That’s all from this informative guide!

Conclusion

In Python, the built-in functions “range()” and “iter.tools()” are used to repeat “N” times. Additionally, one can multiply a string by a number to repeat that specific string “N” times. The “range()” function is used along with for loop to repeat any value “N” times by providing a range within its parameter. The “iter.tools()” method repeats an infinite “N” times value if we set its parameter value to default. This write-up provides a comprehensive overview of all the methods to repeat the “N” times in Python.

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For loops

There are two ways to create loops in Python: with the for-loop and the while-loop.

When do I use for loops

for loops are used when you have a block of code which you want to repeat a fixed number of times. The for-loop is always used in combination with an iterable object, like a list or a range. The Python for statement iterates over the members of a sequence in order, executing the block each time. Contrast the for statement with the »while» loop, used when a condition needs to be checked each iteration or to repeat a block of code forever. For example:

For loop from 0 to 2, therefore running 3 times.

for x in range(0, 3): print("We're on time %d" % (x))

While loop from 1 to infinity, therefore running forever.

x = 1 while True: print("To infinity and beyond! We're getting close, on %d now!" % (x)) x += 1

When running the above example, you can stop the program by pressing ctrl+c at the same time. As you can see, these loop constructs serve different purposes. The for loop runs for a fixed amount of times, while the while loop runs until the loop condition changes. In this example, the condition is the boolean True which will never change, so it will run forever.

How do they work?

If you’ve done any programming before, you have undoubtedly come across a for loop or an equivalent to it. Many languages have conditions in the syntax of their for loop, such as a relational expression to determine if the loop is done, and an increment expression to determine the next loop value. In Python, this is controlled instead by generating the appropriate sequence. Basically, any object with an iterable method can be used in a for loop. Even strings, despite not having an iterable method — but we’ll not get on to that here. Having an iterable method basically means that the data can be presented in list form, where there are multiple values in an orderly fashion. You can define your own iterables by creating an object with next() and iter() methods. This means that you’ll rarely be dealing with raw numbers when it comes to for loops in Python — great for just about anyone!

Nested loops

When you have a block of code you want to run x number of times, then a block of code within that code which you want to run y number of times, you use what is known as a «nested loop». In Python, these are heavily used whenever someone has a list of lists — an iterable object within an iterable object.

for x in range(1, 11): for y in range(1, 11): print('%d * %d = %d' % (x, y, x*y))

Like the while loop, the for loop can be made to exit before the given object is finished. This is done using the break statement, which will immediately drop out of the loop and continue execution at the first statement after the block. You can also have an optional else clause, which will run should the for loop exit cleanly — that is, without breaking.

for x in range(3): if x == 1: break

Examples

for x in range(3): print(x) else: print('Final x = %d' % (x))

string = "Hello World" for x in string: print(x)

collection = ['hey', 5, 'd'] for x in collection: print(x)

list_of_lists = [ [1, 2, 3], [4, 5, 6], [7, 8, 9]] for list in list_of_lists: for x in list: print(x)

Creating your own iterable

class Iterable(object): def __init__(self,values): self.values = values self.location = 0 def __iter__(self): return self def next(self): if self.location == len(self.values): raise StopIteration value = self.values[self.location] self.location += 1 return value

Your own range generator using yield

def my_range(start, end, step): while start yield start start += step for x in my_range(1, 10, 0.5): print(x)

A note on `range`

The »range» function is seen so often in for statements that you might think range is part of the for syntax. It is not: it is a Python built-in function that returns a sequence following a specific pattern (most often sequential integers), which thus meets the requirement of providing a sequence for the for statement to iterate over. Since for can operate directly on sequences, there is often no need to count. This is a common beginner construct (if they are coming from another language with different loop syntax):

mylist = ['a', 'b', 'c', 'd'] for i in range(len(mylist)): # do something with mylist[i]

It can be replaced with this:

mylist = ['a', 'b', 'c', 'd'] for v in mylist: # do something with v

Consider for var in range(len(something)): to be a flag for possibly non-optimal Python coding.

More resources

ForLoop (last edited 2022-01-23 09:18:40 by eriky )

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How to Repeat a Function in Python

To repeat a function in Python, the easiest way is with a for loop.

def multiplyBy2(num): return num*2 x = 2 for i in range(0,4): x = multiplyBy2(x) print(x) #Output: 32

You can also use a while loop to repeat a function in Python.

def multiplyBy2(num): return num*2 x = 2 while x < 30: x = multiplyBy2(x) print(x) #Output: 32

When working with data in our Python programs, iteration can be incredibly useful to perform tasks for us many times. We can use iteration to repeat functions easily in Python.

Iteration in Python comes in two forms, for loops and while loops.

In a for loop, we define the number of times you want a block of code to repeat explicitly.

For example, if I want to create a loop which will run five times, I can use the range() function to build a range from 0 to 5.

for i in range(0,5): print(i) #Output: 0 1 2 3 4

We can repeat functions in Python easily with for loops.

For example, if we have a function which multiplies a number by 2, and we want to multiply another number by 2 five times, we can loop five times and repeat the function five times.

Below is an example in Python of how to repeat a function five times with a for loop.

def multiplyBy2(num): return num*2 x = 2 for i in range(0,4): x = multiplyBy2(x) print(x) #Output: 32

Repeating Functions with While Loops in Python

You can also repeat functions with Python by using while loops. While loops allow us to iterate depending on the conditions we pass the loop.

For example, with while loops you need to use a logical expression which will determine whether to keep iterating or not.

In our example above, we wanted to loop five times to multiply our number by 2 five times.

Let’s instead use a while loop which will keep multiplying until our number is at least 30.

Below is an example using Python of how to use a while loop to repeat a function.

def multiplyBy2(num): return num*2 x = 2 while x < 30: x = multiplyBy2(x) print(x) #Output: 32

Hopefully this article has been useful for you to learn how to repeat a function in Python.

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