import time, random, datetime, io def read(): return random.random() with io.open('/tmp/t.csv', 'a', encoding='utf8') as f: while True: v = read() l = '%f,%f\n' % (time.time(), v) if type(l) != type(u''): l = l.decode('utf8') f.write(l) f.flush() time.sleep(1)