[EMAIL PROTECTED] wrote: > Being a Matlab user wanting to switch to Python/SciPy,
Fantastic! You might be interested in joining the numpy mailing list. There are a lot more of us numpy devs and users there than here. http://www.scipy.org/Mailing_Lists > I'd like to > know how the following Matlab code would be written in Python: > > % First, just some artificial data > N = 1000000 ; > input = sign(randn(1, N)) ; > a = (1 : N) ; > % This is what I'd like to do; > % for indices where the input has a certain value, compute and store > something > % for indices where the input has another certain value, compute and > store something else > output(input < 0) = 10 * a(input < 0) ; > output(input > 0) = 20 * a(input > 0) ; > > I have tried the following in Python: > N = 1000000 > input = sign(randn(N)) > a = arange(N) > output = zeros(N) > output[input < 0] = 10 * a[input < 0] > output[input > 0] = 20 * a[input > 0] > > However, that gives me in IndexError. When reporting that you get an error, copy-and-pasting the full traceback is highly recommended. We can give you an answer much more quickly if you do. In this case, your example works fine for me with numpy 1.0.3 (after supplying the missing imports). In [1]: from numpy import * In [2]: N = 1000000 In [3]: input = sign(random.randn(N)) In [4]: a = arange(N) In [5]: output = zeros(N) In [6]: output[input < 0] = 10 * a[input < 0] In [7]: output[input > 0] = 20 * a[input > 0] If you are still having problems, please join us on numpy-discussion with the full traceback. -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
