Python client

EVA ICS machine learning kit Python library can work both with and with no server installed. If there is no server installed, data is processed on the client side.

Installation

Workstation/standalone

pip3 install evaics.ml

The above command must be typed in the system terminal. If using Anaconda Navigator, open a terminal window for an environment:

Anaconda terminal

EVA ICS venv

If the module is installed on EVA ICS v4 node, use the following command to add ML kit Python client into EVA ICS venv:

eva venv add evaics.ml

Querying data

HTTP Lazy initialization

from evaics.client import HttpClient

# the import automatically enabled additional client methods
import evaics.ml

client = HttpClient('http://127.0.0.1:7727',
                         user='operator', password='xxx')
# If Machine learning kit server is used with a front-end and API methods
# are mapped to the same port, the variable can be just set to True.
# If Machine learning kit server is not installed, do not set this
# variable or set it to None
client.mlkit = 'http://127.0.0.1:8811'

# initialize an empty request
req = client.history_df()

BUS/RT Lazy initialization

BUS/RT access requires ML kit server to be deployed.

# initialize BUS/RT if not connected. Not required for EVA ICS Python
# services and Python macros

bus = busrt.client.Client('/opt/eva4/var/bus.ipc', 'test-py')
bus.connect()

client = busrt.rpc.Rpc(bus)
# the name of ML kit server service instance
client.mlkit = 'eva.svc.ml'

# initialize an empty request
req = client.history_df()

Standard initialization

from evaics.client import HttpClient
from evaics.ml import HistoryDF

client = HttpClient('http://127.0.0.1',
                         user='operator', password='xxx')

# both HTTP and BUS/RT RPC client can be used
req = HistoryDF(client).with_mlkit(True)

OID mapping

with “oid” method item state can fields can be mapped to specific data frame columns. Set True to map field with the default column name (e.g. sensor:tests/temp1/value), a string to specify a custom column name:

req.oid('sensor:tests/temp1', status='temp1st', value='temp1')

If a state field is not required, it can be omitted.

OID mapping from CSV file

A client can read mapping from a CSV file with fields “oid”, “status”, “value” and “database” (can be omitted if ML kit server is used). This can be done either with specifying “params_csv” argument in the request constructor or calling “read_params_csv” request method:

req = client.history_df(params_csv='params_csv')
# or
req = HistoryDF(client, params_csv='params.csv')
# or
req = req.read_params_csv('params.csv')

Usage example

All the methods can be called as chained:

result = client.history_df(
    params_csv='params.csv').t_start(
        '2023-02-22 23:23:34').t_end(
        '2023-02-23 03:33:19').fill('10T').fetch(t_col='keep')

Uploading data

Prepare a request the same way as querying (database parameter for OIDs is ignored). Then use “push” method to push a file. The file extension must match:

  • .arrows for Arrow streams

  • .arrow for Arrow files

  • .csv for CSV files

Instead of a file, a pyarrow table can be submitted. The database service can be specified in a short manner (e.g. “id” for “eva.db.id”) or in full. Example:

result = client.history_df(params_csv='params.csv').push(
    'path/to/file.csv', database='mydb')

Module API

class evaics.ml.HistoryDF(client, params_csv: Optional[str] = None)

Fetches data from EVA ICS v4 history databases

When the primary module is imported, the method “history_df()” is automatically added to evaics.client.HttpClient

Create HistoryDF object instance

All configuration methods of the class can be used in chains.

Parameters

client – HTTP client object

Optional:

params_csv: CSV file or stream to read parameters from

database(database: str)

Specify a non-default database

Parameters

database – database name (db service without eva.db. prefix)

fetch(t_col: str = 'keep', tz: str = 'local', output='arrow', strict_col_order=True)

Fetch data

Optional:

output: output format (arrow, pandas or polars) t_col: time column processing, “keep” - keep the column, “drop” - drop the time column tz: time zone (local, custom or None to keep time column as UNIX timestamp), the default is “local” strict_col_order: force strict column ordering (default: True)

Returns

a prepared Pandas DataFrame object

fill(fill: str)

Fill the data frame

Parameters

fill – XN, where X - integer, N - fill type (S for seconds, T for minutes, H for hours, D for days, W for weeks), e.g. 15T for 15 minutes. The values can be rounded to digits after comma as XN:D, e.g 15T:2 - round to 2 digits after comma. The default fill is 1S

limit(limit: int)

Limit the data frame rows to

Parameters

limit – max number of rows

oid(oid: Union[evaics.sdk.OID, str], status=False, value=False, database=None, xopts=None)

Append OID for processing

Parameters

oid – item OID (string or OID object)

Optional:

status: True to keep, a string to rename, False to drop value: same behavior as for keep database: db service to query data from (mlkit srv only) xopts: db service extra opts (mlkit srv only)

push(data, database='default')

Push data

Requires ML kit server

Options:

data: Pandas data frame, file object or file path database: database svc id (default: default)

read_params_csv(f: str)

Read OID mapping from a CSV file

CSV file must have the column “oid” and optional ones “status”, “value” and “database”

Parameters

f – file path or buffer

t_end(t_end: Union[float, str])

Specify the data frame end time

Parameters

t_start – a float (timestamp), a string or a datetime object

t_start(t_start: Union[float, str, datetime.datetime])

Specify the data frame start time

Parameters

t_start – a float (timestamp), a string or a datetime object

with_mlkit(mlkit: Union[bool, str])

Set ML kit url/svc name

Parameters

mlkit – True for the same URL as HMI, svc name or url for other

xopts(xopts: dict)

Extra database options

Parameters

  • xopts – dict of extra options (refer to the EVA ICS database service

  • info) (documentation for more) –