302 lines
14 KiB
Python
302 lines
14 KiB
Python
import time
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from datetime import datetime, timedelta
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import mysql.connector
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from sympy import sympify
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from multiprocessing import Pool
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import random
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import json
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import config
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########################################################################################################################
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# PROCEDURES:
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# Step 1: Query all virtual points
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# Step 2: Create multiprocessing pool to call worker in parallel
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########################################################################################################################
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def calculate(logger):
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while True:
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# outer loop to reconnect server if there is a connection error
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cnx_system_db = None
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cursor_system_db = None
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try:
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cnx_system_db = mysql.connector.connect(**config.myems_system_db)
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cursor_system_db = cnx_system_db.cursor(dictionary=True)
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except Exception as e:
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logger.error("Error in step 0 of virtual point calculate " + str(e))
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if cursor_system_db:
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cursor_system_db.close()
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if cnx_system_db:
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cnx_system_db.close()
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# sleep and continue the outer loop to reconnect the database
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time.sleep(60)
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continue
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print("Connected to MyEMS System Database")
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virtual_point_list = list()
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try:
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cursor_system_db.execute(" SELECT id, name, data_source_id, high_limit, low_limit, address "
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" FROM tbl_points "
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" WHERE is_virtual = TRUE AND object_type = 'ANALOG_VALUE' ")
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rows_virtual_points = cursor_system_db.fetchall()
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if rows_virtual_points is None or len(rows_virtual_points) == 0:
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# sleep several minutes and continue the outer loop to reconnect the database
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time.sleep(60)
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continue
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for row in rows_virtual_points:
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meta_result = {"id": row['id'],
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"name": row['name'],
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"data_source_id": row['data_source_id'],
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"high_limit": row['high_limit'],
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"low_limit": row['low_limit'],
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"address": row['address']}
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virtual_point_list.append(meta_result)
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except Exception as e:
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logger.error("Error in step 1 of virtual point calculate " + str(e))
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# sleep and continue the outer loop to reconnect the database
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time.sleep(60)
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continue
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finally:
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if cursor_system_db:
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cursor_system_db.close()
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if cnx_system_db:
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cnx_system_db.close()
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# shuffle the virtual point list for randomly calculating
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random.shuffle(virtual_point_list)
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print("Got all virtual points in MyEMS System Database")
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################################################################################################################
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# Step 2: Create multiprocessing pool to call worker in parallel
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################################################################################################################
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p = Pool(processes=config.pool_size)
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error_list = p.map(worker, virtual_point_list)
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p.close()
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p.join()
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for error in error_list:
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if error is not None and len(error) > 0:
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logger.error(error)
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print("go to sleep ...")
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time.sleep(60)
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print("wake from sleep, and continue to work...")
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########################################################################################################################
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# Step 1: get start datetime and end datetime
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# Step 2: parse the expression and get all points in substitutions
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# Step 3: query points value from historical database
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# Step 4: evaluate the equation with points values
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########################################################################################################################
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def worker(virtual_point):
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cnx_historical_db = None
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cursor_historical_db = None
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try:
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cnx_historical_db = mysql.connector.connect(**config.myems_historical_db)
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cursor_historical_db = cnx_historical_db.cursor()
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except Exception as e:
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return "Error in step 1.1 of virtual point worker " + str(e) + " for '" + virtual_point['name'] + "'"
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print("Start to process virtual point: " + "'" + virtual_point['name']+"'")
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####################################################################################################################
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# step 1: get start datetime and end datetime
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####################################################################################################################
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try:
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query = (" SELECT MAX(utc_date_time) "
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" FROM tbl_analog_value "
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" WHERE point_id = %s ")
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cursor_historical_db.execute(query, (virtual_point['id'],))
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row = cursor_historical_db.fetchone()
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except Exception as e:
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return "Error in step 1.2 of virtual point worker " + str(e) + " for '" + virtual_point['name'] + "'"
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start_datetime_utc = datetime.strptime(config.start_datetime_utc, '%Y-%m-%d %H:%M:%S')
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start_datetime_utc = start_datetime_utc.replace(minute=0, second=0, microsecond=0, tzinfo=None)
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if row is not None and len(row) > 0 and isinstance(row[0], datetime):
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# replace second and microsecond with 0
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# note: do not replace minute in case of calculating in half hourly
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start_datetime_utc = row[0].replace(second=0, microsecond=0, tzinfo=None)
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# start from the next time slot
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start_datetime_utc += timedelta(minutes=config.minutes_to_count)
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end_datetime_utc = datetime.utcnow().replace()
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end_datetime_utc = end_datetime_utc.replace(second=0, microsecond=0, tzinfo=None)
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if end_datetime_utc <= start_datetime_utc:
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return "it's too early to calculate" + " for '" + virtual_point['name'] + "'"
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print("start_datetime_utc: " + start_datetime_utc.isoformat()[0:19]
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+ "end_datetime_utc: " + end_datetime_utc.isoformat()[0:19])
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############################################################################################################
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# Step 2: parse the expression and get all points in substitutions
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############################################################################################################
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point_list = list()
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try:
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########################################################################################################
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# parse the expression and get all points in substitutions
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########################################################################################################
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address = json.loads(virtual_point['address'])
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# example: '{"expression": "x1-x2", "substitutions": {"x1":1,"x2":2}}'
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if 'expression' not in address.keys() \
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or 'substitutions' not in address.keys() \
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or len(address['expression']) == 0 \
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or len(address['substitutions']) == 0:
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return "Error in step 2.1 of virtual point worker for '" + virtual_point['name'] + "'"
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expression = address['expression']
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substitutions = address['substitutions']
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for variable_name, point_id in substitutions.items():
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point_list.append({"variable_name": variable_name, "point_id": point_id})
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except Exception as e:
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return "Error in step 2.2 of virtual point worker " + str(e) + " for '" + virtual_point['name'] + "'"
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############################################################################################################
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# Step 3: query points value from historical database
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############################################################################################################
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print("getting point values ...")
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point_values_dict = dict()
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if point_list is not None and len(point_list) > 0:
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try:
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for point in point_list:
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point_id = str(point['point_id'])
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query = (" SELECT utc_date_time, actual_value "
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" FROM tbl_analog_value "
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" WHERE point_id = %s AND utc_date_time >= %s AND utc_date_time < %s "
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" ORDER BY utc_date_time ")
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cursor_historical_db.execute(query, (point_id, start_datetime_utc, end_datetime_utc, ))
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rows = cursor_historical_db.fetchall()
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if rows is None or len(rows) == 0:
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point_values_dict[point_id] = None
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else:
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point_values_dict[point_id] = dict()
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for row in rows:
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point_values_dict[point_id][row[0]] = row[1]
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except Exception as e:
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return "Error in step 3.1 virtual point worker " + str(e) + " for '" + virtual_point['name'] + "'"
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############################################################################################################
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# Step 4: evaluate the equation with points values
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############################################################################################################
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print("getting date time set for all points...")
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utc_date_time_set = set()
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if point_values_dict is not None and len(point_values_dict) > 0:
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for point_id, point_values in point_values_dict.items():
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if point_values is not None and len(point_values) > 0:
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utc_date_time_set = utc_date_time_set.union(point_values.keys())
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print("evaluating the equation with SymPy...")
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normalized_values = list()
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############################################################################################################
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# Converting Strings to SymPy Expressions
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# The sympify function(that’s sympify, not to be confused with simplify) can be used to
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# convert strings into SymPy expressions.
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############################################################################################################
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try:
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expr = sympify(expression)
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print("the expression to be evaluated: " + str(expr))
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for utc_date_time in utc_date_time_set:
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meta_data = dict()
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meta_data['utc_date_time'] = utc_date_time
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####################################################################################################
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# create a dictionary of Symbol: point pairs
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####################################################################################################
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subs = dict()
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####################################################################################################
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# Evaluating the expression at current_datetime_utc
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####################################################################################################
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if point_list is not None and len(point_list) > 0:
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for point in point_list:
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point_id = str(point['point_id'])
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actual_value = point_values_dict[point_id].get(utc_date_time, None)
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if actual_value is None:
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break
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subs[point['variable_name']] = actual_value
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if len(subs) != len(point_list):
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continue
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####################################################################################################
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# To numerically evaluate an expression with a Symbol at a point,
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# we might use subs followed by evalf,
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# but it is more efficient and numerically stable to pass the substitution to evalf
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# using the subs flag, which takes a dictionary of Symbol: point pairs.
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####################################################################################################
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meta_data['actual_value'] = expr.evalf(subs=subs)
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normalized_values.append(meta_data)
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except Exception as e:
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return "Error in step 4.1 virtual point worker " + str(e) + " for '" + virtual_point['name'] + "'"
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print("saving virtual points values to historical database...")
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if len(normalized_values) > 0:
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try:
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add_values = (" INSERT INTO tbl_analog_value "
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" (point_id, utc_date_time, actual_value) "
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" VALUES ")
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for meta_data in normalized_values:
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add_values += " (" + str(virtual_point['id']) + ","
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add_values += "'" + meta_data['utc_date_time'].isoformat()[0:19] + "',"
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add_values += str(meta_data['actual_value']) + "), "
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print("add_values:" + add_values)
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# trim ", " at the end of string and then execute
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cursor_historical_db.execute(add_values[:-2])
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cnx_historical_db.commit()
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except Exception as e:
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return "Error in step 4.2 virtual point worker " + str(e) + " for '" + virtual_point['name'] + "'"
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if cursor_historical_db:
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cursor_historical_db.close()
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if cnx_historical_db:
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cnx_historical_db.close()
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return None
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