range() is a built-in function of Python. It is used when a user needs to perform an action for a specific number of times.
range() in Python(3.x) is just a renamed version of a function called
xrange in Python(2.x). The range() function is used to generate a sequence of numbers.
range() is commonly used in for looping hence, knowledge of same is key aspect when dealing with any kind of Python code. Most common use of
range() function in Python is to iterate sequence type (List, string etc.. ) with for and while loop.
range() Basics :
In simple terms,
range() allows user to generate a series of numbers within a given range. Depending on how many arguments user is passing to the function, user can decide where that series of numbers will begin and end as well as how big the difference will be between one number and the next.
range() takes mainly three arguments.
- start: integer starting from which the sequence of integers is to be returned
- stop: integer before which the sequence of integers is to be returned.
The range of integers end at stop – 1.
- step: integer value which determines the increment between each integer in the sequence
0 1 2 3 4 5 6 7 8 9 10 20 30 40 Sum of first 10 natural number : 55
There are three ways you can call
range(stop)takes one argument.
range(start, stop)takes two arguments.
range(start, stop, step)takes three arguments.
When user call
range() with one argument, user will get a series of numbers that starts at 0 and includes every whole number up to, but not including, the number that user have provided as the stop. For Example –
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
When user call range() with two arguments, user get to decide not only where the series of numbers stops but also where it starts, so user don’t have to start at 0 all the time. User can use
range() to generate a series of numbers from X to Y using a range(X, Y). For Example -arguments
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
range(start, stop, step)
When user call
range() with three arguments, user can choose not only where the series of numbers will start and stop but also how big the difference will be between one number and the next. If user don’t provide a step, then range() will automatically behave as if the step is 1.
0 3 6 9 12 15 18 21 24 27 0 5 10 15 20 25 30 35 40 45
In this example, we are printing an even number between 0 to 10 so we choose our starting point from 0(start = 0) and stop the series at 10(stop = 10). For printing even number the difference between one number and the next must be 2 (step = 2) after providing a step we get a following output ( 0, 2, 4, 8).
Incrementing with range using positive step :
If user want to increment, then user need
step to be a positive number. For example:
2 4 6 8 10 12 14 16 18 20 22 24 0 4 8 12 16 20 24 28 15 18 21 24
Decrementing with range using negative step :
If user want to decrement, then user need
step to be a negative number. For example:
25 23 21 19 17 15 13 11 9 7 5 3 30 26 22 18 14 10 6 2 25 22 19 16 13 10 7 4 1 -2 -5
Using float Numbers in Python range() :
range() function doesn’t support the float numbers. i.e. user cannot use floating-point or non-integer number in any of its argument. User can use only integer numbers.For example
for i in range(3.3): TypeError: 'float' object cannot be interpreted as an integer
Concatenation of two range() functions
The result from two
range() functions can be concatenated by using the
chain() method of
itertools module. The
chain() method is used to print all the values in iterable targets one after another mentioned in its arguments.
Concatenating the result 0 1 2 3 4 10 12 14 16 18
Accessing range() with index value
A sequence of numbers is returned by the
range() function as it’s object that can be accessed by its index value. Both positive and negative indexing is supported by its object.
First element: 0 Last element: 9 Fifth element: 4
Points to remember about Python
range() function :
range()function only works with the integers i.e. whole numbers.
- All argument must be integers. User can not pass a string or float number or any other type in a start, stop and step argument of a range().
- All three arguments can be positive or negative.
- The step value must not be zero. If a step is zero python raises a ValueError exception.
range()is a type in Python
- User can access items in a
range()by index, just as user do with a list:
- Slicing range() function in Python
- range() vs xrange() in Python
- Python | range() method
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- Python | range() does not return an iterator
- Python - Reverse Range in String List
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- Python | Merge Range Characters in List
- Python - Specific Range Addition in List
- Python | Assign range of elements to List
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