Question

So I have a need to pass around a numpy array in my PyQt Application. I first tried using the new-style signals/slots, defining my signal with:

newChunkToProcess = pyqtSignal(np.array()), however this gives the error:
TypeError: Required argument ‘object’ (pos 1) not found

I have worked out how to do this with the old-style signals and slots using
self.emit(SIGNAL("newChunkToProcess(PyQt_PyObject)"), np.array([5,1,2])) – (yes, that’s just testing data :), but I was wondering, is it possible to do this using the new-style system?

Answer 1

The type you’re looking for is np.ndarray
You can tell this from the following code:

>>> arr = np.array([])  # create an array instance
>>> type(arr)           # ask 'what type is this object?'
<type 'numpy.ndarray'>

So your signal should look more like:

newChunkToProcess = pyqtSignal(np.ndarray)

(Notice I’m passing the type np.ndarray, rather than an array instance as you tried).
If you don’t want to worry about the type of the argument, you could instead use:

newChunkToProcess = pyqtSignal(object)

This should let you send any data type at all through the signal.

Also: numpy and Qt do not share any major functionality that I know of. In fact, the two are quite complementary and make a very powerful combination.