The range() and xrange() are two functions that could be used to iterate a certain number of times in for loops in Python. In Python3, there is no xrange, but the range function behaves like xrange in Python2. If you want to write code that will run on both Python2 and Python3, you should use range(). Both are implemented in different ways and have different characteristics associated with them. The points of comparison are:
- Return Type
- Memory
- Operation Usage
- Speed
Python range() function
The Python range() function returns a sequence of numbers, in a given range. The most common use of it is to iterate sequences on a sequence of numbers using Python loops.
Python xrange() function
The xrange() function in Python is used to generate a sequence of numbers, similar to the Python range() function. The Python xrange() is used only in Python 2.x whereas the range() function in Python is used in Python 3.x.
Return Type in range() vs xrange()
This xrange() function returns the generator object that can be used to display numbers only by looping. The only particular range is displayed on demand and hence called “lazy evaluation“, whereas, in Python range() function returns a range object (a type of iterable).
Python3
# initializing a with range()a = range(1, 10000)# initializing a with xrange()x = xrange(1, 10000)# testing the type of aprint("The return type of range() is : ")print(type(a))# testing the type of xprint("The return type of xrange() is : ")print(type(x)) |
Output:
The return type of range() is :
<type 'list'>
The return type of xrange() is :
<type 'xrange'>
Speed of xrange() and range() Function
The variable storing the range created by range() takes more memory as compared to the variable storing the range using xrange(). The basic reason for this is the return type of range() is list and xrange() is xrange() object.
Python3
import sys# initializing a with range()a = range(1,10000)# initializing a with xrange()x = xrange(1,10000)# testing the size of a# range() takes more memoryprint ("The size allotted using range() is : ")print (sys.getsizeof(a))# testing the size of x# xrange() takes less memoryprint ("The size allotted using xrange() is : ")print (sys.getsizeof(x)) |
Output:
The size allotted using range() is :
80064
The size allotted using xrange() is :
40
Operations Usage of xrange() and range() Function
A range() returns the list, all the operations that can be applied on the list can be used on it. On the other hand, as xrange() returns the xrange object, operations associated with the list cannot be applied to them, hence a disadvantage.
Python3
# initializing a with range()a = range(1,6)# initializing a with xrange()x = xrange(1,6)# testing usage of slice operation on range()# prints without errorprint ("The list after slicing using range is : ")print (a[2:5])# testing usage of slice operation on xrange()# raises errorprint ("The list after slicing using xrange is : ")print (x[2:5]) |
Error:
Traceback (most recent call last):
File "1f2d94c59aea6aed795b05a19e44474d.py", line 18, in
print (x[2:5])
TypeError: sequence index must be integer, not 'slice'
Output:
The list after slicing using range is :
[3, 4, 5]
The list after slicing using xrange is :
Difference between range() and xrange() in Python
Because of the fact that xrange() evaluates only the generator object containing only the values that are required by lazy evaluation, therefore is faster in implementation than range().
Important Points:
- If you want to write code that will run on both Python 2 and Python 3, use range() as the xrange function is deprecated in Python 3.
- range() is faster if iterating over the same sequence multiple times.
- xrange() has to reconstruct the integer object every time, but range() will have real integer objects. (It will always perform worse in terms of memory, however)
|
range() |
xrange() |
|---|---|
| Returns a list of integers. | Returns a generator object. |
| Execution speed is slower | Execution speed is faster. |
| Takes more memory as it keeps the entire list of elements in memory. | Takes less memory as it keeps only one element at a time in memory. |
| All arithmetic operations can be performed as it returns a list. | Such operations cannot be performed on xrange(). |
| In python 3, xrange() is not supported. | In python 2, xrange() is used to iterate in for loops. |
