Terrance N. Phillip wrote: > Given a and b, two equal length lists of integers, I want c to be > [a1-b1, a2-b2, ... , an-bn]. I can do something like: > > c = [0] * len(a) > for ndx, item in enumerate(a): > c[ndx] = item - b[ndx] > > But I'm wondering if there's a better way, perhaps that avoids a loop? > > Nick. > > (I seem to recall from my distant past that this sort of thing was dead > easy with APL... c = a-b, more or less.)
If you're doing this kind of thing often, look into using Numeric. http://numeric.scipy.org In [21]: from Numeric import array In [22]: a = array(range(10)) In [23]: b = array(range(10, 20)) In [24]: c = a - b In [25]: c Out[25]: [-10,-10,-10,-10,-10,-10,-10,-10,-10,-10,] -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
