[Numpy-discussion] concatenation changes dtype

Travis Oliphant oliphant.travis at ieee.org
Sat Sep 16 17:36:39 CDT 2006


Martin Wiechert wrote:
> Hi list,
>
> Apparently r_[x,x] does not necessarily have the same dtype as x:
>
>   
>>>> from numpy import *
>>>> dt = dtype ([('a', 'b'), ('f4', 'i4')])
>>>> x = zeros ((1,), dt)
>>>> x.dtype
>>>>         
> dtype([('a', '|i1'), ('f4', '<i4')])
>   

Did you mean to make a data-type that was a 1-byte integer followed by a 
4-byte integer with field names of 'a' and 'f4'?

Perhaps you meant:

dtype([('a','f4'),('b','i4')])

which is a 4-byte float followed by a 4-byte integer.


-Travis







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