Source code for summer.lod

# -*- coding: utf-8 -*-
# Time-stamp: < lod.py (2016-02-14 11:37) >

# Copyright (C) 2009-2016 Martin Slouf <martin.slouf@sourceforge.net>
#
# This file is a part of Summer.
#
# Summer is free software; you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 3 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""List of dictionaries (*lod*) -- simple yet powerfull in memory data
structure, ie. *grid*.

Thanks to: http://stackoverflow.com/questions/1038160/python-data-structure-for-maintaing-tabular-data-in-memory

This module is not imported into public *summer* namespace, so you should
import it directly::

    from summer import lod

"""
import csv
import logging
import io

logger = logging.getLogger(__name__)


[docs]def lod_populate(lod: list, fin: io.IOBase): """Populate lod using CSV file. Args: lod (list): list to be extended with data fin (io.IOBase): file-like object in CSV format """ rdr = csv.DictReader(fin, delimiter=";", quotechar='"') lod.extend(rdr)
[docs]def lod_query(lod: list, filter_obj=None, sort_keys=None): """Lookup in lod based on query. Args: lod (list): lod to be used filter_obj: filter to be used sort_keys: sort criteria Returns: list: collection of matching rows """ if filter_obj is not None: tmp = (r for r in lod if list(filter_obj(r))) if sort_keys is not None: tmp = sorted(lod, key=lambda r: [r[k] for k in sort_keys]) else: tmp = list(lod) return tmp
[docs]def lod_lookup(lod: list, **kw): """Lookup in lod by attribute values. Args: lod (list): lod to be used **kw (dict): use keyword arguments. keys are column names, their value is attribute value Returns: list: first matching row """ for row in lod: for k, v in kw.items(): if row[k] != str(v): break else: return row return None