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

  Names of columns on which queries will be joined

• combine_columns: typing.Union

  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

  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