Convert python list with None values to numpy array with nan values

Question

I am trying to convert a list that contains numeric values and None values to numpy.array, such that None is replaces with numpy.nan

Answer 1

What about

my_array = np.array(map(lambda x: numpy.nan if x==None else x, my_list))

Answer 2

You simply have to explicitly declare the data type:

>>> my_list = [3, 5, 6, None, 6, None]
>>> np.array(my_list, dtype=np.float)
array([  3.,   5.,   6.,  nan,   6.,  nan])