Python range function [Explained with Examples]

In this article, we will explain you the below points about the Python range function with code examples.

1. range function introduction and syntax
2. Python range object indexing and slicing
3. range with floating numbers
4. Converting range object to list object
5. range reverse

Quick Summary

The following is the quick summary about range() function in Python.

Python range function

Python range() function can be used to generate a sequence of numbers from a given start to a stop with the step.

Syntax:

range(start, stop, step)

Parameters:

Python’s range function accepts below three parameters.

Parameter	Explanation	Required	Default Value
start	range starts at this value and it is inclusive	Optional	0
stop	range end at this value and it is exclusive	Required	No default values
step	at each iteration range will be incremented by step	Optional	1

Return type:

It returns range class type. You can access the given parameters directly as range.start, range.stop and range.step.

range with stop parameter

If you pass only one integer parameter to range’s constructor, it will be considered as stop and start will be taken as 0 and step will be 1.

Code Thread:

for i in range(5):
    print(i)

Output:

0
1
2
3
4

range with start and stop parameters

If you pass two parameters to range constructor it will treat first parameter as start and second parameter as stop. It will return a sequence of number from start to stop with the default step as 1.

Code Thread:

for i in range(1, 6):
    print(i)

Output:

with range(1, 6), we will get numbers from 1 to 5 since stop(6) is exclusive.

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2
3
4
5

range with step

In the above examples, we have used range() function with start and stop parameters. Now, we will use it with step parameter as well.

Code Thread:

for i in range(1, 10, 2):
    print(i)

Output:

with range(1, 10, 2), we are passing step as 2. It will add 2 to the current start at every step.

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3
5
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9

Negative numbers range

Range object also works the negative start, stop and step numbers.

Code Thread 1:

for i in range(-5, -1):
    print(i)

Output:

-5
-4
-3
-2

Code Thread 2:

for i in range(-1, -10):
    print(i)

Output:

#no output since -1 is greater than -10 and step is 1

Code Thread 3:

for i in range(-1, -6, -1):
    print(i)

Output:

-1
-2
-3
-4
-5

range function with characters

The range function does not accept characters as parameters. However, you can use ord() and chr() functions to get range of characters.

Code Thread:

char_range = range(ord('a'), ord('z')+1)

print(list([chr(i) for i in char_range]))

Output:

['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

---

Accessing Range values with index and slicing

You can access range object values with indexing and slicing as same as list elements access.

Code Thread for Range indexing:

result = range(1, 11, 1)

# access third element with index number 2
third_element = result[2]
print('third_element:', third_element)

Output:

third_element: 3

Code Thread for range slicing:

result = range(1, 11, 1)

# access elements from 2 to 5 index number with slicing and slicing returns range object
part = result[2:6]
print('slice:', list(part))

Output:

slice: [3, 4, 5, 6]

---

range(length) to get List indexes

You can use the range() function with stop as length of the list to access the elements with the index number.

Code Thread:

employee_salaries = [100, 200, 400, 300, 600, 500]

for i in range(len(employee_salaries)):
    print(employee_salaries[i])

Output:

100
200
400
300
600
500

---

Convert Python range object to list

Python range can be converted to list by passing range object to list() constructor as a parameter.

Code Thread:

print(list(range(10)))

Output:

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

---

How to generate range reverse?

With the below two methods you can get reverse range in Python.

Method 1: using reversed() function

Alternatively, You can the in-built reversed() function to get reverse iterator of range object.

Code Thread:

#range reverse using reversed function

def get_reverse_range(start, stop, step):
    return reversed(range(start, stop, step))


start = 10
stop = 30
step = 5
reverse_range = get_reverse_range(start, stop, step)
print(list(reverse_range))

Output:

[25, 20, 15, 10]

Method 2: using __reversed__ method

You can also use __reversed__() method of range object to get the range in reverse order.

Code Thread:

#range reverse using __reversed__() method

def get_reverse_range(start, stop, step):
    return range(start, stop, step).__reversed__()


start = 10
stop = 30
step = 5
reverse_range = get_reverse_range(start, stop, step)
print(list(reverse_range))

Output:

[25, 20, 15, 10]

---

How does range function works for Floating numbers?

In this section, we will see how to get sequence of floating point numbers.

Using standard range() for float – Throws error

The range() function does not work with floating point numbers, it only works with positive and negative integers. If you pass floating numbers you will be thrown the TypeError.

Code Thread:

start = 1.0
stop = 2.0
step = 0.1
print(range(start, stop, step))

Output:

TypeError: 'float' object cannot be interpreted as an integer

Range of float numbers using numpy.arange()

To generate a range of floating point numbers, we can use arange() function from numpy the module as below. The return type of arange() will be numpy.ndarray.

Code Thread:

import numpy as np

start = 1.0
stop = 2.0
step = 0.1

result = np.arange(start, stop, step)
print(type(result))
print(result)

Output:

<class 'numpy.ndarray'>
[1.  1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9]

---

Frequently Asked Questions

How to get range with inclusive numbers

In Python, the range object’s stop parameter is exclusive. If you want to include it in the range then you just have to add 1 to the stop.

Code Thread:

def get_range_inclusive(start, stop, step):
    return range(start, stop+1, step)


start = 10
stop = 31
step = 2
print(list(get_range_inclusive(start, stop, step)))

Output:

[10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32]

---

Using ‘in’ operator to check if element presents

Like lists in Python, you can use in operator with range also for membership test as in the below code thread.

Code Thread:

range1 = range(1, 100)
if 45 in range1:
    print(True)
else:
    print(False)

Output:

True

Python concatenating two ranges

We can use chain method from the itertools library to iterate over the two ranges at a time and concatenate them.

Code Thread:

from itertools import chain

range1 = range(1,6)
range2 = range(6,11)
for element in chain(range1, range2):
    print(element)

Output:

1
2
3
4
5
6
7
8
9
10

Python range start at 1

The range function accepts start parameter. You can pass this start parameter to get range object which starts from 1. If you don’t pass by default it will be 0.

Code Thread:

for i in range(1, 6):
    print(i)

Output:

1
2
3
4
5

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