On Wed, 06 Feb 2013 10:37:07 -0500, Vladimir Ivkovic wrote: > Hi Python experts, > > I am working with an array of data and am trying to plot several columns > of data which are not continuous; i.e. I would like to plot columns 1:4 > and 6:8, without plotting column 5. The syntax I am currently using is: > > oplot (t,d[:,0:4]) > > The question is: How do I specify within the above command, for columns > 6:8 to be plotted?
You don't give us enough information to be sure: - you don't tell us what library oplot comes from; - you don't tell us what t is; - you don't tell us what d is; - and d[:,0:4] looks like it could be a SyntaxError or a typo. But assuming that what you tell us actually is correct, then obviously if oplot (t,d[:,0:4]) plots columns 1-4, then oplot (t,d[:,5:8]) will surely plot columns 6-8. Python counts starting from 0, not 1, and uses half-open intervals: when giving a range of indexes, like 0:4, Python interprets that as follows: item at index 0 (the first item) item at index 1 (the second item) item at index 2 (the third item) item at index 3 (the fourth item) with index 4 being excluded. So 5:8 will include the sixth through eighth items. This notation is called "slicing", and d[0:4] is called "a slice". The idea is that if you number the items starting from zero, and imagine the boundaries between items (shown as | vertical lines): |0|1|2|3|4|5|6|7|8|9|10|11 ... then always slice on the boundary to the left of the given number: slice [0:4] => |0|1|2|3| slice [5:8] => |5|6|7| The only tricky part is remembering to count from zero instead of one. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
