bw2data.query#

Attributes#

operators

Classes#

`Dictionaries`	Pretends to be a single dictionary when applying a `Query` to multiple databases.
`Filter`	A filter on a dataset.
`Query`	A container for a set of filters applied to a dataset.
`Result`	A container that wraps a filtered dataset. Returned by a calling a `Query` object. A result object functions like a read-only dictionary; you can call `Result[some_key]`, or `some_key in Result`, or `len(Result)`.

Functions#

`NF`(value)	Shortcut for a name filter
`PF`(value)	Shortcut for a reference product filter
`try_op`(f, x, y)

Module Contents#

class bw2data.query.Dictionaries(*args)[source]#

Pretends to be a single dictionary when applying a Query to multiple databases.

Usage:: first_database = Database(…).load() second_database = Database(…).load() my_joined_dataset = Dictionaries(first_database, second_database) search_results = Query(filter_1, filter_2)(my_joined_dataset)

items()[source]#

dicts = ()[source]#

class bw2data.query.Filter(key, function, value)[source]#

A filter on a dataset.

The following functions are supported:

“<”, “<=”, “==”, “>”, “>=”: Mathematical relations

“is”, “not”: Identity relations. Work on any Python object.

“in”, “notin”: List or string relations.

“iin”, “iis”, “inot”: Case-insensitive string relations.

“len”: Length relation.

In addition, any function which defines a relationship between an input and an output can also be used.

Examples

All name values are “foo”: Filter("name", "is", "foo")
All name values include the string “foo”: Filter("name", "has", "foo")
Category (a list of categories and subcategories) includes “foo”: Filter("category", "has", "foo")

Parameters:

key (*) – The field to filter on.
function (*) – One of the pre-defined filters, or a callable object.
value (*) – The value to test against.

Returns:

A Result object which wraps a new data dictionary.

function[source]#

key[source]#

value[source]#

class bw2data.query.Query(*filters)[source]#

A container for a set of filters applied to a dataset.

Filters are applied by calling the Query object, and passing the dataset to filter as the argument. Calling a Query with some data returns a Result object with the filtered dataset.

Parameters:: filters (*) – One or more Filter objects.

add(filter_)[source]#

Add another filter.

Parameters:: *filter_* (Filter) – A Filter object.

filters = [][source]#

class bw2data.query.Result(result)[source]#

A container that wraps a filtered dataset. Returned by a calling a Query object. A result object functions like a read-only dictionary; you can call Result[some_key], or some_key in Result, or len(Result).

The dataset can also be sorted, using sort(field); the underlying data is then a collections.OrderedDict.

Parameters:: result (*) – The filtered dataset.

items()[source]#

keys()[source]#

sort(field, reverse=False)[source]#

Sort the filtered dataset. Operates in place; does not return anything.