Question

I want to combine 2 parts of the same array to make a complex array:

Data[:,:,:,0] , Data[:,:,:,1]

These don’t work:

x = np.complex(Data[:,:,:,0], Data[:,:,:,1])
x = complex(Data[:,:,:,0], Data[:,:,:,1])

Am I missing something? Does numpy not like performing array functions on complex numbers? Here’s the error:

TypeError: only length-1 arrays can be converted to Python scalars

Answer 1

This seems to do what you want:

numpy.apply_along_axis(lambda args: [complex(*args)], 3, Data)

Here is another solution:

# The ellipsis is equivalent here to ":,:,:"...
numpy.vectorize(complex)(Data[...,0], Data[...,1])

And yet another simpler solution:

Data[...,0] + 1j * Data[...,1]

PS: If you want to save memory (no intermediate array):

result = 1j*Data[...,1]; result += Data[...,0]

devS’ solution below is also fast.