Different usages of xrange and range in 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:

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>>> 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:

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>>> 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]     &G T;>> 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:

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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:

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

Output results:

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<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:

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

Output results:

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

Summarize:

Two are basically used in the cycle.

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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:

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

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

The code is as follows	Copy Code
A = xrange (0,100) Print type (a) Print a Print a[0], a[1]

The performance of Xrange is better than range, especially when it comes back very big! Try to use xrange, unless you are going to return a list.