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October 2011

96 participants
82 discussions

iterate over multiple arrays
by David Froger Oct. 1, 2011

Oct. 1, 2011

Hy everybody, I'm wondering what is the (best) way to apply the same function to multiple arrays. For example, in the following code: from numpy import * def f(arr): return arr*2 a = array( [1,1,1] ) b = array( [2,2,2] ) c = array( [3,3,3] ) d = array( [4,4,4] ) a = f(a) b = f(b) c = f(c) d = f(d) I would like to replace : a = f(a) b = f(b) c = f(c) d = f(d) with something like that, but which really modify a,b,c and d: for x in [a,b,c,d]: x = f(x) So having something like a pointer on the arrays. Thanks for your help ! David --

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Weird upcast behavior with 1.6.x, working as intended?
by Olivier Delalleau Oct. 1, 2011

Oct. 1, 2011

Hi, This is with numpy 1.6.1 under Linux x86_64, testing the upcast mechanism of "scalar + array": >>> import numpy; print (numpy.array(3, dtype=numpy.complex128) + numpy.ones(3, dtype=numpy.float32)).dtype complex64 Since it has to upcast my array (float32 is not "compatible enough" with complex128), why does it upcast it to complex64 instead of complex128? As far as I can tell 1.4.x and 1.5.x versions of numpy are indeed upcasting to complex128. Thanks, -=- Olivier

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