extract floats from gr message queue without numpy

numpy_version.py

msg = tb.msgq_out.delete_head()
msg_string = msg.to_string()
samples = np.fromstring(msg_string, dtype='float32')

python_version.py

# pull from message queue
msg = tb.msgq_out.delete_head()
msg_string = msg.to_string()

samples = []
# extract floats from msg string
# it is slow. very slow! :/
for i in range(0,len(sample),4):
    # unpack sample to have a tuples
    unpacked = struct.unpack_from('f', sample[i:i+4])
    samples.append(unpacked[0])