[Numpy-discussion] Determine if numpy is installed from an extension

Peter Notebaert peno@telenet...
Tue Feb 2 16:42:11 CST 2010


I have written a C-extension for python that uses arrays from python, does calculations on them and returns a result on that.

I have now also added the possibility to provide numpy arrays. However this is not a requirement. Python arrays (lists) are still allowed also. I check in the C-code which kind of arrays are provided.

That all works ok, but I have one problem. In the initialisation function for the extension I call import_array to initialise the numpy library.
The problem is if numpy is not installed on the system, that this call generates a message and an error and the rest of the routine is aborted.
Via the source code of numpy I discovered that import_array is in fact a macro that calls _import_array and checks its return value to give the message.
But even it I call _import_array myself and check for the return code, after the initialisation routine has finished I still get the message 'No module named numpy.core.multiarray'.

How can I test if numpy is installed on the system from the extension so that I do not active the numpy functionality and that it is still able to use my extension, but then without numpy support?

I have searched in the manual and documentation, searched in google, but I do not find an answer on that question.
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