Fastest way to generate delimited string from 1d numpy array

Question

I have a program which needs to turn many large one-dimensional numpy arrays of floats into delimited strings. I am finding this operation quite slow relative to the mathema

Answer 1

I think you could experiment with numpy.savetxt passing a cStringIO.StringIO object as a fake file...

Or maybe using str(x) and doing a replacement of the whitespaces by commas (edit: this won't work quite well because the str does an ellipsis of large arrays :-s).

As the purpose of this was to send the array over the network, maybe there are better alternatives (more efficient both in cpu and bandwidth). The one I pointed out in a comment to other answer as to encode the binary representation of the array as a Base64 text block. The main inconvenient for this to be optimal is that the client reading the chunk of data should be able to do nasty things like reinterpret a byte array as a float array, and that's not usually allowed in type safe languages; but it could be done quickly with a C library call (and most languages provide means to do this).

In case you cannot mess with bits, there's always the possibility of processing the numbers one by one to convert the decoded bytes to floats.

Oh, and watch out for the endiannes of the machines when sending data through the network: convert to network order -> base64encode -> send | receive -> base64decode -> convert to host order