Returns input function that would feed Pandas DataFrame into the model.

Used in the notebooks

Used in the tutorials

x pandas DataFrame object.
y pandas Series object or DataFrame. None if absent.
batch_size int, size of batches to return.
num_epochs int, number of epochs to iterate over data. If not None, read attempts that would exceed this value will raise OutOfRangeError.
shuffle bool, whether to read the records in random order.
queue_capacity int, size of the read queue. If None