flowmachine.features.utilities.combine_first

Class CombineFirst

CombineFirst(*, first_query: flowmachine.core.query.Query, other_query: flowmachine.core.query.Query, join_columns: Union[str, Collection[str]], combine_columns: Union[str, Collection[str]])

Source: flowmachine/features/utilities/combine_first.py

Given two queries 'first_query' and 'other_query', fill null or missing values in the result of 'first_query' using those in the result of 'other_query'. Values that will be filled include rows that are present in 'other_query' but not 'first_query', and rows present in both queries but where fields in 'first_query' have the value NULL. Somewhat analogous to pandas.DataFrame.combine_first(), except that here we specify the columns on which the queries will be (full outer) joined.

Attributes

• cache

• column_names

• column_names_as_string_list

• dependencies

• fully_qualified_table_name

• index_cols

• is_stored

• query_id

• query_state

• query_state_str

• table_name

Parameters

• first_query: flowmachine.core.query.Query

  Query whose nulls will be filled

• other_query: flowmachine.core.query.Query

  Query whose values will be used to fill nulls in first_query

• join_columns: typing.Union[str, typing.Collection[str]]

  Names of columns on which queries will be joined

• combine_columns: typing.Union[str, typing.Collection[str]]

  Names of columns in which null values will be filled

Note

Relevant column names are assumed to be the same in both queries (i.e. nulls in column 'col1' of first_query are filled with values from column 'col1' of other_query)

Methods

cache

cache

Source: flowmachine/core/query.py

Returns

• bool

  True is caching is switched on.

column_names

column_names

Source: flowmachine/features/utilities/combine_first.py

Returns the column names.

Returns

• typing.List[str]

  List of the column names of this query.

column_names_as_string_list

column_names_as_string_list

Source: flowmachine/core/query.py

Get the column names as a comma separated list

Returns

• str

  Comma separated list of column names

dependencies

dependencies

Source: flowmachine/core/query.py

Returns

• set

  The set of queries which this one is directly dependent on.

fully_qualified_table_name

fully_qualified_table_name

Source: flowmachine/core/query.py

Returns a unique fully qualified name for the query to be stored as under the cache schema, based on a hash of the parameters, class, and subqueries.

Returns

• str

  String form of the table's fqn

index_cols

index_cols

Source: flowmachine/core/query.py

A list of columns to use as indexes when storing this query.

Returns

• ixen: list

  By default, returns the location columns if they are present and self.spatial_unit is defined, and the subscriber column.

Examples

daily_location("2016-01-01").index_cols
[['name'], '"subscriber"']

is_stored

is_stored

Source: flowmachine/core/query.py

Returns

• bool

  True if the table is stored, and False otherwise.

query_id

query_id

Source: flowmachine/core/query.py

Generate a uniquely identifying hash of this query, based on the parameters of it and the subqueries it is composed of.

Returns

• str

  query_id hash string

query_state

query_state

Source: flowmachine/core/query.py

Return the current query state.

Returns

• QueryState

  The current query state

query_state_str

query_state_str

Source: flowmachine/core/query.py

Return the current query state as a string

Returns

• str

  The current query state. The possible values are the ones defined in flowmachine.core.query_state.QueryState.

table_name

table_name

Source: flowmachine/core/query.py

Returns a uniquename for the query to be stored as, based on a hash of the parameters, class, and subqueries.

Returns

• str

  String form of the table's fqn