On 19 Sep 2005 00:02:34 -0700, "malv" <[EMAIL PROTECTED]> wrote:
>Simple case: >In this list, how to find all occurences of intervals of n adjacent >indexes having at least one list-member with a value between given >limits. >Visualizing the list as a two-dimensional curve, this is like >horizontally dragging a given rectangle over the curve and finding the >x coordinates where the curve passes through the rectangle.(Define such >a x-index coordinate as the left corner of the rectangle.) > >More complicated case: >Given a pair of rectangles spaced relatively to each other in a fixed >manner. Drag this rectangle pair horizontally over the above >two-dimensional curve and list the indexes of the occurences where the >curve passes simultaneously through both rectangles. >(Define such a x-index coordinate as the leftmost corner of the >rectangle pair). > >These problems can be solved by programming a naive search advancing >index by index. It seems obvious that due to the localized properties >searched for, much more efficient searches should be possible. >After having found the occurence-indexes for one particular rectangle >set, how to find the pattern occurences after changing one or more >rectangle parameters? > for the first problem, maybe (untested beyond the below): >>> from itertools import groupby >>> data = [5+i%5 for i in xrange(40)] >>> data [5, 6, 7, 8, 9, 5, 6, 7, 8, 9, 5, 6, 7, 8, 9, 5, 6, 7, 8, 9, 5, 6, 7, 8, 9, 5, 6, 7, 8, 9, 5, 6, 7, 8, 9, 5, 6, 7, 8, 9] >>> [g.next()[0] for k,g in groupby(enumerate(data), lambda t: 6<t[1]<9) if k] [2, 7, 12, 17, 22, 27, 32, 37] By the time you figure a more efficient way, this can have solved it for quite a long sequence. But since an efficient solution seems a lot like homework, I'll leave it to you ;-) Or is this a bioinfo problem in disguise? Regards, Bengt Richter -- http://mail.python.org/mailman/listinfo/python-list
