Python range

range is a Python function for integer number

1、range(int_num)，输出一个从0-(int_num-1)的list

range(10)
[0,1,2,3,4,5,6,7,8,9]

2、range(start, end)，输出一个从start到end-1的list

range(1,5)
1,2,3,4

3 range(start, end, steps) will product a list from start to end by steps. The list`s last element will not larger than end - 1.

range(1,6,2)
[1,3,5]
range(2,6,2)
[2,4] 

frange is a Python function for float number, its head file is pylab. You should import pylab when you use this function.

1 frange(int_num) will product a list from 0 to int_num

pylab.frange(4)
[ 0.  1.  2.  3.  4.]# it`s from 0 to 4

2 frange(start, end) will product a list from start to end and the step is 1.0

print pylab.frange(1,4)
[ 1.  2.  3.  4.]

3 frange(start, end, steps) will product a list from start to end by steps.

pylab.frange(1,4,0.5)
[ 1.   1.5  2.   2.5  3.   3.5  4. ]
pylab.frange(1,4.4,0.5)
[ 1.   1.5  2.   2.5  3.   3.5  4.   4.5]

xrange is a Python function. Its use and parameters are same with range. But it is looked as a type and return an object, the object is iterable,  rather than a list. It is faster and less memory than range

>>>xrange(1,3)# produce a object
xrange(1,3)
>>>x = xrange(1,3)
>>>x
xrange(1,3)
>>>x[1]
2
>>>range(1,3)# produce a list
[1,2]