python3 cannot find xrange definition

Because the range function was canceled in python3, and the xrange function was renamed to range, the range function can be used directly now.

Range
function description: , generate a list range([start,] stop[, step])according startto the stopspecified range and the step size set by step.

>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> range(2,10)
[2, 3, 4, 5, 6, 7, 8, 9]
>>> range(2,10,2)
[2, 4, 6, 8]
>>> type(_)
<type 'list'>

xrange

Function description: rangeThe usage of and is exactly the same, but the return is a generator.

>>> xrange(10)
xrange(10)
>>> xrange(2,10)
xrange(2, 10)
>>> xrange(2,10,2)
xrange(2, 10, 2)
>>> type(_)
<type 'xrange'>
>>> list(xrange(2, 10, 2))
[2, 4, 6, 8]

However, when you want to generate a large sequence of numbers, using xrange will have much better performance than range, because you don't need to open up a large memory space as soon as it comes up. These two are basically used when looping.

>>> r = range(0,50)
>>> r
[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, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49]
>>> type(r)
<type 'list'>
>>> print r[0],r[49]
0 49
>>> xr = xrange(0,50)
>>> xr
xrange(50)
>>> type(xr)
<type 'xrange'>
>>> print xr[0],xr[49]
0 49
>>> list(xr) == r
True

Use as much as possible in recycling xrange so that performance can be improved, unless you're returning a list

>>> for i in range(0,50): print i,

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 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
>>> for i in xrange(0,50): print i,

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 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49