2008/7/9 Benjamin Goudey <[EMAIL PROTECTED]>: > I have a very large list of integers representing data needed for a > histogram that I'm going to plot using pylab. However, most of these > values (85%-95%) are zero and I would like to remove them to reduce > the amount of memory I'm using and save time when it comes to plotting > the data. To do this, I'm trying to find the best way to remove all of > the zero values and produce a list of indices of where the non-zero > values used to be. > > For example, if my original list is [0,0,1,2,1,0,0] I would like to > produce the lists [1,2,1] (the non zero values) and [2,3,4] (indices > of where the non-zero values used to be). Removing non-zero values is > very easy but determining the indicies is where I'm having difficulty. > > Thanks in advance for any help
>>> l = [0, 0, 1, 2, 1, 0, 0] >>> zip(*[(item, index) for (index, item) in enumerate(l) if item != 0]) [(1, 2, 1), (2, 3, 4)] > -- > http://mail.python.org/mailman/listinfo/python-list > -- Wbr, Andrii Mishkovskyi. He's got a heart of a little child, and he keeps it in a jar on his desk. -- http://mail.python.org/mailman/listinfo/python-list
