On 2015-11-15 16:27, fl wrote: > When I learn slice, I have a new question on the help file. If I > set: > > pp=a[0:10:2] > > pp is array([1, 3]) > > I don't know how a[0:10:2] gives array([1, 3]). > > I know matlab a lot, but here it seems quite different. Could you > tell me what meaning a[0:10:2] is?
Well, if it a matlab.array was a well-behaved object it would just give you "0". As your copy/paste on the help for a slice stated, the first number is where it starts (0), the second number is where it ends (10, exclusive), and the 3rd number (2) is the stride. To demonstrate: >>> a = list(range(20)) >>> a [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19] >>> a[0:10:2] [0, 2, 4, 6, 8] >>> a[:10:2] [0, 2, 4, 6, 8] >>> a[0:10] [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] So note that the stride of 2 provides every other one while a stride of three provides every 3rd value >>> a[0:10:3] [0, 3, 6, 9] -tkc -- https://mail.python.org/mailman/listinfo/python-list
