ampli/py/util.py

import psycopg2 as pg
from configparser import ConfigParser
import pandas.io.sql as psql
import datetime as dt
import numpy as np


def config(filename='database.ini', section='postgresql'):
    """Config parser from
    http://www.postgresqltutorial.com/postgresql-python/connect/"""
    # create a parser
    parser = ConfigParser()
    # read config file
    parser.read(filename)

    # get section, default to postgresql
    db = {}
    if parser.has_section(section):
        params = parser.items(section)
        for param in params:
            db[param[0]] = param[1]
    else:
        raise Exception(
            'Section {0} not found in the {1} file'.format(section, filename))

    return db


def getQuery(query, qparams=[]):
    """
    Get single query
    """
    conn = False

    try:
        params = config()

        print("Connecting to database")

        conn = pg.connect(**params)
        cur = conn.cursor()

        # Get table
        print("Retrieving table")
        dataframe = psql.read_sql(query, conn, params=qparams)

        cur.close()

        print("Table recieved")

        return dataframe

    except (Exception, pg.DatabaseError) as error:
        print(error)
        return None

    finally:
        if conn is not False:
            conn.close()
            print('Database connection closed')


def pickleQuery(query, path, qparams=[]):
    dq = getQuery(query, qparams)
    dq.to_pickle(path)
    print("Table pickled")


def getkwh(datestart, dateend, timestart, timeend, subset):
    query = """
    SELECT SUBSTRING(comb.icp_id FROM 2 FOR 6)::int AS icp_id, comb.read_time, COALESCE(kwh_tot, 0) AS kwh_tot
    FROM
    (
        SELECT read_time, icp_id
        FROM
        (
            SELECT read_time 
            FROM GENERATE_SERIES(%(tsstart)s::timestamp, %(tsend)s::timestamp, 
                '30 minutes'::interval) read_time
        ) AS tsdata CROSS JOIN public.icp_sample
    ) AS comb
    LEFT JOIN
    (
        SELECT *, read_date + CONCAT(period / 2, ':', period %% 2 * 30, ':00')::time AS read_time
        FROM (
            SELECT  a.icp_id
                 , a.read_date
                 , c.period
                 , sum(c.read_kwh) as kwh_tot
                 , sum(case when a.content_code = 'UN' then c.read_kwh else 0 end) as kwh_un
                 , sum(case when a.content_code in ('CN','EG') then c.read_kwh else 0 end) as kwh_cn
            FROM    coup_prd.coupdatamaster a,
                unnest(a.read_array) WITH ORDINALITY c(read_kwh, period)
            WHERE   a.read_date >= to_date(%(datestart)s,'yyyy-mm-dd')
             and   a.read_date <  to_date(%(dateend)s,'yyyy-mm-dd')
             and   a.content_code  ~ ('UN|CN|EG')
             AND   a.icp_id IN (
                SELECT icp_id FROM public.icp_sample
             )
            GROUP BY 1, 2, 3
        ) AS coup_tall
    ) AS tall_timestamp 
    ON comb.read_time = tall_timestamp.read_time AND comb.icp_id = tall_timestamp.icp_id;
    """
    pdict = {
        'datestart': datestart,
        'dateend': dateend,
        'tsstart': timestart,
        'tsend': timeend
        # 'subset': subset
    }
    print("Getting data with parameters:")
    print(pdict)
    qdf = getQuery(query, pdict)
    print("Optimising")
    qdf['icp_id'] = qdf['icp_id'].astype(np.int32)
    qdf['kwh_tot'] = qdf['kwh_tot'].astype(np.float32)
    print("Done")
    return(qdf)




if __name__ == "__main__":
    dv = getQuery('SELECT version()').version[0]
    print('PostgreSQL database version:')
    print(dv)