otp.query#

class query(path, *config, **params)#

Bases: object

Constructs a query object with a certain path. Keyword arguments specify query parameters.

You also can pass an instance of otp.query.config class as the second positional argument to specify a query.

Parameters

  • path (str) –

    path to an .otq file. If path is relative, then it’s assumed that file is located in one of the directories specified in OneTick OTQ_FILE_PATH configuration variable. If there are more than one query in the file, then its name should be specified in the format <path>::<query-name>.

    Also prefix remote://<database-name>:: can be used to specify if query is located on the remote server. If such path exists locally too, then this file is inspected to get info about query and its pins as we can’t get this info from remote server.

  • config – optional otp.query.config object. This object can be used to specify different query options, e.g. output columns.

  • params – parameters for the query. Dictionary if parameters’ names and their values.

Examples

Adding local query and applying it to the source:

>>> q = otp.query('/otqs/some.otq::some_query', PARAM1='val1', PARAM2=3.14)  
>>> t = otp.Tick(A=1)
>>> t = t.apply(q)

Adding remote query:

>>> otp.query('remote://DATABASE::/otqs/some.otq::some_query', PARAM1='val1', PARAM2=3.14)  
<onetick.py.sources.query object at ...>

Creating python wrapper function around query from .otq file:

>>> def add_w(src):
...     schema = dict(src.schema)
...     if 'W' in schema:
...         raise ValueError("column 'W' already exists")
...     else:
...         schema['W'] = str
...     q = otp.query('add_w.otq::w', otp.query.config(output_columns=list(schema.items())))
...     return src.apply(q)
>>> t = otp.Tick(A=1)
>>> t = add_w(t)
>>> t.schema
{'A': <class 'int'>, 'W': <class 'str'>}
>>> t['X'] = t['W'].str.upper()
>>> otp.run(t)
        Time  A      W      X
0 2003-12-01  1  hello  HELLO
Raises

ValueError, TypeError –

class config(output_columns=None)#

Bases: object

The config allows to specify different query options.

Parameters

output_columns (str, list, dict, optional) –

The parameter defines what the outputs columns are. Default value is None that means no output fields after applying query for every output pin.

The input string value means that output columns are the same as inputs for every output pin.

A list of tuples allows to define output columns with their types; for example [('x', int), ('y', float), ...]. Applicable for every output pin.

A dict allows to specify output columns for every output pin.

Examples

>>> otp.query('/otqs/some.otq::some_query', otp.query.config(output_columns=[('X': int)]))
Raises

TypeError, ValueError –

__call__(*ticks, **pins)#

Return object representing outputs of the query. This object can be used to get a specified output pin of the query as a new onetick.py.Source.

Examples

>>> query = otp.query('/otqs/some.otq::some_query', PARAM1='val1')  
>>> query()['OUT']  
<onetick.py.core.source.Source at ...>
to_eval_string()#

Converts query object to OneTick’s eval string.

update_params(**new_params)#

Update dictionary of parameters of the query.

property str_params#

Query parameters converted to OneTick string representation.