The difference between xrange and range in Python _python

Range Function Description: Range ([Start,] stop[, step], which generates a sequence based on the range specified by start and stop, and steps that are set.
Range Example:

Copy Code code as follows:

>>> Range (5)
[0, 1, 2, 3, 4]
>>> Range (1,5)
[1, 2, 3, 4]
>>> Range (0,6,2)
[0, 2, 4]

xrange function Description: The usage is exactly the same as range, but instead of generating an array, it is a generator.
xrange Example:

Copy Code code as follows:

>>> xrange (5)
Xrange (5)
>>> List (xrange (5))
[0, 1, 2, 3, 4]
>>> xrange (1,5)
Xrange (1, 5)
>>> list (xrange (1,5))
[1, 2, 3, 4]
>>> xrange (0,6,2)
Xrange (0, 6, 2)
>>> list (xrange (0,6,2))
[0, 2, 4]

As you can see from the above example: to generate a large number of sequences, using xrange will be much better than range performance, because you do not need to open up a large amount of memory space, these two are basically in the loop with:

Copy Code code as follows:

For I in range (0, 100):
Print I

For I in xrange (0, 100):
Print I

The results of both outputs are the same, in fact there are many different, range will directly generate a list object:

Copy Code code as follows:

A = range (0,100)
Print type (a)
Print a
Print a[0], a[1]

Output results:

Copy Code code as follows:

<type ' list ' >
[0, 1, 2, 3, 4.5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 33, 34 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 3, 64, 65.66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 94, 95, 96, 97, 98, 99]
0 1

Instead of generating a list directly, Xrange returns one of its values each time it is invoked:

Copy Code code as follows:

A = xrange (0,100)
Print type (a)
Print a
Print a[0], a[1]

Output results:

Copy Code code as follows:

<type ' xrange ' >
Xrange (100)
0 1