def feature(self, instrument, field, start_index, end_index, freq):
    field = str(field).lower()[1:]
    uri_data = self._uri_data.format(instrument.lower(), field, freq)
    if (not os.path.exists(uri_data)):
        get_module_logger('data').warning(('WARN: data not found for %s.%s' % (instrument, field)))
        return pd.Series()
    series = read_bin(uri_data, start_index, end_index)
    return series
def feature(self, instrument, field, start_index, end_index, freq):
    field = str(field).lower()[1:]
    uri_data = self._uri_data.format(instrument.lower(), field, freq)
    if (not os.path.exists(uri_data)):
        get_module_logger('data').warning(('WARN: data not found for %s.%s' % (instrument, field)))
        return pd.Series()
    series = read_bin(uri_data, start_index, end_index)
    return series