Extract fields from segment line strings into a dictionary

def _read_segment_lines(segment_lines):
    """
    Extract fields from segment line strings into a dictionary

    """
    # Dictionary for segment fields
    segment_fields = {}

    # Each dictionary field is a list
    for field in SEGMENT_SPECS.index:
        segment_fields[field] = [None] * len(segment_lines)

    # Read string fields from signal line
    for i in range(len(segment_lines)):
        (segment_fields['seg_name'][i], segment_fields['seg_len'][i]) = _rx_segment.findall(segment_lines[i])[0]

        # Typecast strings for numerical field
        if field == 'seg_len':
            segment_fields['seg_len'][i] = int(segment_fields['seg_len'][i])

    return segment_fields