Brightway2-data¶

Configuration¶

The configuration for brightway2 is implemented as a singleton class that is created when brightway2 is imported.

class bw2data.configuration.Config¶

A singleton that stores configuration settings

property biosphere¶

Get name for biosphere database from user preferences.

Default name is biosphere3; change this by changing config.p["biosphere_database"].

property global_location¶

Get name for global location from user preferences.

Default name is GLO; change this by changing config.p["global_location"].

Projects¶

class bw2data.project.ProjectManager¶

copy_project(new_name, switch=True)¶: Copy current project to a new project named new_name. If switch, switch to new project.

delete_project(name=None, delete_dir=False)¶

Delete project name, or the current project.

name is the project to delete. If name is not provided, delete the current project.

By default, the underlying project directory is not deleted; only the project name is removed from the list of active projects. If delete_dir is True, then also delete the project directory.

If deleting the current project, this function sets the current directory to default if it exists, or to a random project.

Returns the current project.

property output_dir¶

Get directory for output files.

Uses environment variable BRIGHTWAY2_OUTPUT_DIR; preferences['output_dir']; or directory output in current project.

Returns output directory path.

purge_deleted_directories()¶

Delete project directories for projects which are no longer registered.

Returns number of directories deleted.

report()¶

Give a report on current projects, including installed databases and file sizes.

Returns tuples of (project name, number of databases, size of all databases (GB)).

request_directory(name)¶

Return the absolute path to the subdirectory dirname, creating it if necessary.

Returns False if directory can’t be created.

Base classes for metadata¶

Serialized Dictionary¶

class bw2data.serialization.SerializedDict(dirpath=None)¶

Base class for dictionary that can be serialized to or unserialized from disk. Uses JSON as its storage format. Has most of the methods of a dictionary.

Upon instantiation, the serialized dictionary is read from disk.

backup()¶: Write a backup version of the data to the backups directory.

deserialize()¶: Load the serialized data. Can be replaced with other serialization formats.

flush()¶: Serialize the current data to disk.

keys() → a set-like object providing a view on D’s keys¶

property list¶: List the keys of the dictionary. This is a property, and does not need to be called.

load()¶: Load the serialized data. Creates the file if not yet present.

pack(data)¶: Transform the data, if necessary. Needed because JSON must have strings as dictionary keys.

random()¶: Return a random key.

serialize(filepath=None)¶

Method to do the actual serialization. Can be replaced with other serialization formats.

Args:

filepath (str, optional): Provide an alternate filepath (e.g. for backup).

unpack(data)¶: Return serialized data to true form.

values() → an object providing a view on D’s values¶

Compound JSON dictionary¶

JSON hash tables don’t support keys like ("biosphere", "an emission"), so the pack and unpack methods are used to transform data from Python to JSON and back.

class bw2data.serialization.CompoundJSONDict(dirpath=None)¶

Subclass of SerializedDict that allows tuples as dictionary keys (not allowed in JSON).

pack(data)¶: Transform the dictionary to a list because JSON can’t handle lists as keys

unpack(data)¶: Transform data back to a dictionary

Pickled Dictionary¶

class bw2data.serialization.PickledDict(dirpath=None)¶

Subclass of SerializedDict that uses the pickle format instead of JSON.

deserialize()¶: Load the serialized data. Can be replaced with other serialization formats.

Metadata stores¶

databases¶

class bw2data.meta.Databases(dirpath=None)¶

A dictionary for database metadata. This class includes methods to manage database versions. File data is saved in databases.json.

backup()¶: Write a backup version of the data to the backups directory.

clear() → None. Remove all items from D.¶

deserialize()¶: Load the serialized data. Can be replaced with other serialization formats.

flush()¶: Serialize the current data to disk.

get(k[, d]) → D[k] if k in D, else d. d defaults to None.¶

increment_version(database, number=None)¶: Increment the database version. Returns the new version.

items() → a set-like object providing a view on D’s items¶

keys() → a set-like object providing a view on D’s keys¶

property list¶: List the keys of the dictionary. This is a property, and does not need to be called.

load()¶: Load the serialized data. Creates the file if not yet present.

pack(data)¶: Transform the data, if necessary. Needed because JSON must have strings as dictionary keys.

pop(k[, d]) → v, remove specified key and return the corresponding value.¶: If key is not found, d is returned if given, otherwise KeyError is raised.

popitem() → (k, v), remove and return some (key, value) pair¶: as a 2-tuple; but raise KeyError if D is empty.

random()¶: Return a random key.

serialize(filepath=None)¶

Method to do the actual serialization. Can be replaced with other serialization formats.

Args:

filepath (str, optional): Provide an alternate filepath (e.g. for backup).

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D¶

unpack(data)¶: Return serialized data to true form.

update([E, ]**F) → None. Update D from mapping/iterable E and F.¶: If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v

values() → an object providing a view on D’s values¶

version(database)¶: Return the database version

methods¶

class bw2data.meta.Methods(dirpath=None)¶

A dictionary for method metadata. File data is saved in methods.json.

backup()¶: Write a backup version of the data to the backups directory.

clear() → None. Remove all items from D.¶

deserialize()¶: Load the serialized data. Can be replaced with other serialization formats.

flush()¶: Serialize the current data to disk.

get(k[, d]) → D[k] if k in D, else d. d defaults to None.¶

items() → a set-like object providing a view on D’s items¶

keys() → a set-like object providing a view on D’s keys¶

property list¶: List the keys of the dictionary. This is a property, and does not need to be called.

load()¶: Load the serialized data. Creates the file if not yet present.

pack(data)¶: Transform the dictionary to a list because JSON can’t handle lists as keys

pop(k[, d]) → v, remove specified key and return the corresponding value.¶: If key is not found, d is returned if given, otherwise KeyError is raised.

popitem() → (k, v), remove and return some (key, value) pair¶: as a 2-tuple; but raise KeyError if D is empty.

random()¶: Return a random key.

serialize(filepath=None)¶

Method to do the actual serialization. Can be replaced with other serialization formats.

Args:

filepath (str, optional): Provide an alternate filepath (e.g. for backup).

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D¶

unpack(data)¶: Transform data back to a dictionary

update([E, ]**F) → None. Update D from mapping/iterable E and F.¶: If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v

values() → an object providing a view on D’s values¶

normalizations¶

class bw2data.meta.NormalizationMeta(dirpath=None)¶: A dictionary for normalization metadata. File data is saved in methods.json.

weightings¶

class bw2data.meta.WeightingMeta(dirpath=None)¶: A dictionary for weighting metadata. File data is saved in methods.json.

Mappings¶

mapping¶

class bw2data.meta.Mapping(dirpath=None)¶

A dictionary that maps object ids, like ("Ecoinvent 2.2", 42), to integers. Needed because parameter arrays have integer row and column fields.

File data is saved in mapping.pickle.

This dictionary does not support setting items directly; instead, use the add method to add multiple keys.

add(keys)¶

Add a set of keys. These keys can already be in the mapping; only new keys will be added.

Args:

keys (list): The keys to add.

delete(keys)¶

Delete a set of keys.

Args:: keys (list): The keys to delete.

geomapping¶

class bw2data.meta.GeoMapping(*args, **kwargs)¶

A dictionary that maps location codes to integers. Needed because parameter arrays have integer geo fields.

File data is stored in geomapping.pickle.

This dictionary does not support setting items directly; instead, use the add method to add multiple keys.

Data stores¶

DataStore¶

class bw2data.DataStore(name)¶

Base class for all Brightway2 data stores. Subclasses should define:

metadata: A Serialized Dictionary instance, e.g. databases or methods. The custom is that each type of data store has a new metadata store, so the data store Foo would have a metadata store foos.

validator: A data validator. Optional. See bw2data.validate.

backup()¶

Save a backup to backups folder.

Returns:: File path of backup.

copy(name)¶

Make a copy of this object with a new name.

This method only changes the name, but not any of the data or metadata.

Args:

name (object): Name of the new object.

Returns:

The new object.

deregister()¶: Remove an object from the metadata store. Does not delete any files.

property filename¶: Remove filesystem-unsafe characters and perform unicode normalization on self.name using utils.safe_filename().

load()¶

Load the intermediate data for this object.

Returns:: The intermediate data.

register(**kwargs)¶: Register an object with the metadata store. Takes any number of keyword arguments.

validate(data)¶: Validate data. Must be called manually.

write(data)¶

Serialize intermediate data to disk.

Args:

data (object): The data

Inventory data backends¶

DatabaseChooser¶

The function bw2data.database.DatabaseChooser() will choose the correct Database class depending on the database backend registered for the database in its metadata. bw2data comes with two backends (see Databases can be stored in different ways).

The function bw2data.database.Database is an alias for bw2data.database.DatabaseChooser(), provided for backwards compatibility.

bw2data.database.DatabaseChooser(name, backend=None)¶

A method that returns a database class instance. The default database type is SingleFileDatabase. JSONDatabase stores each process dataset in indented JSON in a separate file. Database types are specified in databases[database_name][‘backend’].

New database types can be registered with the config object:

config.backends['backend type string'] = MyNewBackendClass

Warning

Registering new backends must be done each time you start the Python interpreter.

To test whether an object is a database subclass, do:

from bw2data.backends import LCIBackend
isinstance(my_database, LCIBackend)

Switching backends¶

bw2data.backends.utils.convert_backend(database_name, backend)¶

Convert a Database to another backend.

bw2data currently supports the default and json backends.

Args:

database_name (unicode): Name of database.
backend (unicode): Type of database. backend should be recoginized by DatabaseChooser.

Returns False if the old and new backend are the same. Otherwise returns an instance of the new Database object.

Custom database backends¶

New database backends should inherit from bw2data.backends.base.LCIBackend:

class bw2data.backends.base.LCIBackend(name)¶

A base class for LCI backends.

Subclasses must support at least the following calls:

load()
write(data)

In addition, they should specify their backend with the backend attribute (a unicode string).

LCIBackend provides the following, which should not need to be modified:

rename
copy
find_dependents
random
process

For new classes to be recognized by the DatabaseChooser, they need to be registered with the config object, e.g.:

config.backends['backend type string'] = BackendClass

Instantiation does not load any data. If this database is not yet registered in the metadata store, a warning is written to stdout.

The data schema for databases in voluptuous is:

exchange = {
        Required("input"): valid_tuple,
        Required("type"): basestring,
        }
exchange.update(uncertainty_dict)
lci_dataset = {
    Optional("categories"): Any(list, tuple),
    Optional("location"): object,
    Optional("unit"): basestring,
    Optional("name"): basestring,
    Optional("type"): basestring,
    Optional("exchanges"): [exchange]
}
db_validator = Schema({valid_tuple: lci_dataset}, extra=True)

where:

valid_tuple is a dataset identifier, like ("ecoinvent", "super strong steel")
uncertainty_fields are fields from an uncertainty dictionary.

Processing a Database actually produces two parameter arrays: one for the exchanges, which make up the technosphere and biosphere matrices, and a geomapping array which links activities to locations.

Args:: name (unicode string): Name of the database to manage.

copy(name)¶

Make a copy of the database.

Internal links within the database will be updated to match the new database name, i.e. ("old name", "some id") will be converted to ("new name", "some id") for all exchanges.

Args:

name (str): Name of the new database. Must not already exist.

delete(**kwargs)¶: Delete data from this instance. For the base class, only clears cached data.

property filename¶: Remove filesystem-unsafe characters and perform unicode normalization on self.name using utils.safe_filename().

find_dependents(data=None, ignore=None)¶

Get sorted list of direct dependent databases (databases linked from exchanges).

Args:

data (dict, optional): Inventory data
ignore (list): List of database names to ignore

Returns:

List of database names

find_graph_dependents()¶

Recursively get list of all dependent databases.

Returns:: A set of database names

load(*args, **kwargs)¶

Load the intermediate data for this database.

If load() does not return a dictionary, then the returned object must have at least the following dictionary-like methods:

__iter__
__contains__
__getitem__
__setitem__
__delitem__
__len__
keys()
values()
items()
items()

However, this method must support the keyword argument as_dict, and .load(as_dict=True) must return a normal dictionary with all Database data. This is necessary for JSON serialization.

It is recommended to subclass collections.MutableMapping (see SynchronousJSONDict for an example of data loaded on demand).

process(*args, **kwargs)¶

Process inventory documents.

Creates both a parameter array for exchanges, and a geomapping parameter array linking inventory activities to locations.

If the uncertainty type is no uncertainty, undefined, or not specified, then the ‘amount’ value is used for ‘loc’ as well. This is needed for the random number generator.

Args:

version (int, optional): The version of the database to process

Doesn’t return anything, but writes two files to disk.

query(*queries)¶: Search through the database.

random()¶

Return a random activity key.

Returns a random activity key, or None (and issues a warning) if the current database is empty.

register(**kwargs)¶

Register a database with the metadata store.

Databases must be registered before data can be written.

Writing data automatically sets the following metadata:

depends: Names of the databases that this database references, e.g. “biosphere”
number: Number of processes in this database.

Args:

format (str, optional): Format that the database was converted from, e.g. “Ecospold”

relabel_data(data, new_name)¶

Relabel database keys and exchanges.

In a database which internally refer to the same database, update to new database name new_name.

Needed to copy a database completely or cut out a section of a database.

For example:

data = {
    ("old and boring", 1):
        {"exchanges": [
            {"input": ("old and boring", 42),
            "amount": 1.0},
            ]
        },
    ("old and boring", 2):
        {"exchanges": [
            {"input": ("old and boring", 1),
            "amount": 4.0}
            ]
        }
    }
print(relabel_database(data, "shiny new"))
>> {
    ("shiny new", 1):
        {"exchanges": [
            {"input": ("old and boring", 42),
            "amount": 1.0},
            ]
        },
    ("shiny new", 2):
        {"exchanges": [
            {"input": ("shiny new", 1),
            "amount": 4.0}
            ]
        }
    }

In the example, the exchange to ("old and boring", 42) does not change, as this is not part of the updated data.

Args:

data (dict): The data to modify
new_name (str): The name of the modified database

Returns:

The modified data

rename(name)¶

Rename a database. Modifies exchanges to link to new name. Deregisters old database.

Args:

name (str): New name.

Returns:

New Database object.

write(data)¶

Serialize data to disk.

data must be a dictionary of the form:

{
    ('database name', 'dataset code'): {dataset}
}

Default backend - databases stored in a SQLite database¶

This backend is a hybrid between SQLite and a document database. See also Storing Python objects in a SQLite3 database is silly! Why not use X document database?

The LCI data is stored in two tables, ActivityDataset and ExchangeDataset. Interactions with the database are mostly done using the Peewee ORM, although some raw SQL queries are used for performance reasons. The table have the following schemas:

CREATE TABLE "activitydataset" (
    "id" INTEGER NOT NULL PRIMARY KEY,
    "data" BLOB NOT NULL,
    "code" TEXT NOT NULL,
    "database" TEXT NOT NULL,
    "location" TEXT,
    "name" TEXT,
    "product" TEXT,
    "type" TEXT
)

CREATE TABLE "exchangedataset" (
    "id" INTEGER NOT NULL PRIMARY KEY,
    "data" BLOB NOT NULL,
    "input_code" TEXT NOT NULL,
    "input_database" TEXT NOT NULL,
    "output_code" TEXT NOT NULL,
    "output_database" TEXT NOT NULL,
    "type" TEXT NOT NULL
)

As one of the fundamental principles of Brightway2 is to have a document-based backend, we incude most data in the column data, which is stored as a binary pickle. Serializing and deserializing is handled automatically by the Peewee interface. However, some attributes can be changed in the database. The following columns are canonical, i.e. they are included when constructing the Activity and Exchange objects:

ActivityDataset.database
ActivityDataset.code
ExchangeDataset.input_database
ExchangeDataset.input_code
ExchangeDataset.output_database
ExchangeDataset.output_code

All other columns are only used to querying and filtering datasets.

class bw2data.backends.peewee.database.SQLiteBackend(*args, **kwargs)¶

delete(keep_params=False, warn=True)¶: Delete all data from SQLite database and Whoosh index

load(*args, **kwargs)¶

Load the intermediate data for this database.

If load() does not return a dictionary, then the returned object must have at least the following dictionary-like methods:

__iter__
__contains__
__getitem__
__setitem__
__delitem__
__len__
keys()
values()
items()
items()

However, this method must support the keyword argument as_dict, and .load(as_dict=True) must return a normal dictionary with all Database data. This is necessary for JSON serialization.

It is recommended to subclass collections.MutableMapping (see SynchronousJSONDict for an example of data loaded on demand).

process()¶

Process inventory documents to NumPy structured arrays.

Use a raw SQLite3 cursor instead of Peewee for a ~2 times speed advantage.

random(filters=True, true_random=False)¶: True random requires loading and sorting data in SQLite, and can be resource-intensive.

search(string, **kwargs)¶

Search this database for string.

The searcher include the following fields:

name
comment
categories
location
reference product

string can include wild cards, e.g. "trans*".

By default, the name field is given the most weight. The full weighting set is called the boost dictionary, and the default weights are:

{
    "name": 5,
    "comment": 1,
    "product": 3,
    "categories": 2,
    "location": 3
}

Optional keyword arguments:

limit: Number of results to return.
boosts: Dictionary of field names and numeric boosts - see default boost values above. New values must be in the same format, but with different weights.
filter: Dictionary of criteria that search results must meet, e.g. {'categories': 'air'}. Keys must be one of the above fields.
mask: Dictionary of criteria that exclude search results. Same format as filter.
facet: Field to facet results. Must be one of name, product, categories, location, or database.
proxy: Return Activity proxies instead of raw Whoosh documents. Default is True.

Returns a list of Activity datasets.

write(data, process=True)¶

Write data to database.

data must be a dictionary of the form:

{
    ('database name', 'dataset code'): {dataset}
}

Writing a database will first deletes all existing data.

Single file - each database in a single file¶

class bw2data.backends.single_file.database.SingleFileDatabase(name)¶

A data store for LCI databases where each database is stored as a pickle file.

Databases are automatically versioned. See below for reversion, etc. methods

Args:: name (str): Name of the database to manage.

property filename¶: Remove filesystem-unsafe characters and perform unicode normalization on self.name using utils.safe_filename().

filename_for_version(version=None)¶

Filename for given version; Default is current version.

Returns:: Filename (not path)

get(code)¶: Get Activity proxy for this dataset

load(version=None, **kwargs)¶

Load the intermediate data for this database.

Can also load previous versions of this database’s intermediate data.

Args:

version (int): Version of the database to load. Default version is the latest version.

Returns:

The intermediate data, a dictionary.

make_latest_version()¶

Make the current version the latest version.

Requires loading data because a new intermediate data file is created.

register(**kwargs)¶

Register a database with the metadata store.

Databases must be registered before data can be written.

revert(version)¶

Return data to a previous state.

Warning

Reverting can lead to data loss, e.g. if you revert from version 3 to version 1, and then save your database, you will overwrite version 2. Use make_latest_version() before saving, which will set the current version to 4.

Args:

version (int): Number of the version to revert to.

property version¶

The current version number (integer) of this database.

Returns:: Version number

versions()¶

Get a list of available versions of this database.

Returns:: List of (version, datetime created) tuples.

write(data, process=True)¶

Serialize data to disk.

Args:

data (dict): Inventory data

Version-control friendly - each database is a JSON file¶

class bw2data.backends.json.database.JSONDatabase(name)¶

A data store for LCI databases. Stores each dataset in a separate file, serialized to JSON.

Instead of loading all the data at once, .load() creates a SynchronousJSONDict, which loads values on demand.

Use this backend by setting "backend":"json" in the database metadata. This is done automatically if you call .register() from this class.

get(code)¶: Get Activity proxy for this dataset

load(as_dict=False, *args, **kwargs)¶: Instantiate SynchronousJSONDict for this database.

register(**kwargs)¶: Register a database with the metadata store, using the correct value for backend, and creates database directory.

write(data, process=True)¶

Serialize data to disk. Most of the time, this data has already been saved to disk, so this is a no-op. The only exception is if data is a new database dictionary.

Normalizes units when found.

Args:

data (dict): Inventory data

class bw2data.backends.json.sync_json_dict.SynchronousJSONDict(dirpath, dirname)¶

A dictionary which stores each value as a separate file on disk. Values are loaded asynchronously (i.e. only as needed), but saved synchronously (i.e. immediately).

Dictionary keys are strings, and do not correspond with filenames. The utility function safe_filename is used to translate keys into allowable filenames, and a separate mapping dictionary is kept to map dictionary keys to filenames.

Retrieving a key returns a frozendict, which can’t be modified. This is to make sure that all changes get synced to disk. To change a dataset you must replace it completely, i.e. this won’t work (it will raise an AttributeError):

my_sync_dict['foo']['bar'] = 'baz'

Instead, you must do:

my_sync_dict['foo'] = {'bar': 'baz'}

After which the ‘foo’ file would be updated.

filepath(key)¶: Use bw2data.utils.safe_filename() to get filename for key key.

from_json(data)¶: Change exchange inputs from lists to tuples (as there is no distinction in JSON, but Python only allows tuples as dictionary keys).

keys() → a set-like object providing a view on D’s keys¶

class bw2data.backends.json.sync_json_dict.frozendict(*args, **kw)¶

A dictionary that can be created but not modified.

From http://code.activestate.com/recipes/414283-frozen-dictionaries/

Impact Assessment data stores¶

ImpactAssessmentDataStore¶

bw2data.ia_data_store.abbreviate(names, length=8)¶

Take a tuple or list, and construct a string, doing the following:

First, apply utils.safe_filename() to each element in names.

Next, take the following, in order:

The first word of the first element in names, lower-cased, where word is defined as everything up to the first empty space character.
Join the rest of the first element (i.e. after the first word) with all other elements. Use the empty space character to join.
In this long string separated by spaces, take the lowercase first character of each word. Add the first word to this new string.
Finally, add a dash, and then the MD5 hash of the entire identifier, where each element is joined by a dash character.

('ReCiPe Endpoint (E,A)', 'human health', 'ionising radiation') becomes 'recipee(hhir-70eeef20a20deb6347ad428e3f6c5f3c'.

The MD5 hash is needed because taking the first characters doesn’t guarantee unique strings.

class bw2data.ia_data_store.ImpactAssessmentDataStore(name)¶

A subclass of DataStore for impact assessment methods.

IA objects are hierarchically structured, and their identifier uses this structure, like ('ecological scarcity 2006', 'total', 'natural resources'). The identifier must be a tuple, i.e. (), not a list, i.e. []. The identifier should only contain unicode strings, and can be of any length >= 1.

Because impact assessment methods are identified by a tuple of strings, e.g. ('ReCiPe Endpoint (E,A)', 'human health', 'ionising radiation'), we need to transform this identifier before it can be used e.g. as a filename. We do this using the abbreviate() function, which returns a single unicode string.

Args:

name (tuple): Name of the IA object to manage. Must be a tuple of unicode strings.

copy(name=None)¶

Make a copy of the method, including its CFs and metadata.

If name is not provided, add “Copy of” to the last element of the original name, e.g. ("foo", "bar") becomes ("foo", "Copy of bar")

Args:

name (tuple, optional): Name of the new method.

Returns:

The new object.

property filename¶: Remove filesystem-unsafe characters and perform unicode normalization on self.name using utils.safe_filename().

get_abbreviation()¶: Retrieve the abbreviation of the method identifier from the metadata store. See class documentation.

register(**kwargs)¶

Register an object with the metadata store.

The metadata key abbreviation is set automatically.

Objects must be registered before data can be written. If this object is not yet registered in the metadata store, a warning is written to stdout.

Takes any number of keyword arguments.

Method¶

class bw2data.method.Method(name)¶

A manager for an impact assessment method. This class can register or deregister methods, write intermediate data, process data to parameter arrays, validate, and copy methods.

The Method class never holds intermediate data, but it can load or write intermediate data. The only attribute is name, which is the name of the method being managed.

Instantiation does not load any data. If this method is not yet registered in the metadata store, a warning is written to stdout.

Methods are hierarchally structured, and this structure is preserved in the method name. It is a tuple of strings, like ('ecological scarcity 2006', 'total', 'natural resources').

The data schema for IA methods is:

Schema([Any(
    [valid_tuple, maybe_uncertainty],         # site-generic
    [valid_tuple, maybe_uncertainty, object]  # regionalized
)])

where:

valid_tuple (tuple): A dataset identifier, like ("biosphere", "CO2").
maybe_uncertainty (uncertainty dict or number): Either a number or an uncertainty dictionary.
object (object, optional) is a location identifier, used only for regionalized LCIA.

Args:

name (tuple): Name of impact assessment method to manage.

add_mappings(data)¶

Add objects to mapping or geomapping, if necessary.

Args:

data (object): The data

process_data(row)¶: Translate data into correct order

write(data, process=True)¶

Serialize intermediate data to disk.

Sets the metadata key num_cfs automatically.

Normalization¶

class bw2data.weighting_normalization.Normalization(name)¶

LCIA normalization data - used to transform meaningful units, like mass or damage, into “person-equivalents” or some such thing.

The data schema for IA normalization is:

Schema([
    [valid_tuple, maybe_uncertainty]
])

where:

valid_tuple is a dataset identifier, like ("biosphere", "CO2")
maybe_uncertainty is either a number or an uncertainty dictionary

add_mappings(data)¶: Add each normalization flow (should be biosphere flows) to global mapping

process_data(row)¶: Return values that match dtype_fields, as well as number or uncertainty dictionary

Weighting¶

class bw2data.weighting_normalization.Weighting(name)¶

LCIA weighting data - used to combine or compare different impact categories.

The data schema for weighting is a one-element list:

Schema(All(
    [uncertainty_dict],
    Length(min=1, max=1)
))

process_data(row)¶: Return an empty tuple (as dtype_fields is empty), and the weighting uncertainty dictionary.

write(data)¶: Because of DataStore assumptions, need a one-element list

User preferences¶

class bw2data.meta.Preferences(*args, **kwargs)¶: A dictionary of project-specific preferences.

Parameters¶

class bw2data.parameters.ParameterManager¶

add_exchanges_to_group(group, activity)¶

Add exchanges with formulas from activity to group.

Every exchange with a formula field will have its original amount value stored as original_amount. This original value can be restored when parameterization is removed from the activity with remove_from_group.

add_to_group(group, activity)¶

Add activity to group.

Creates group if needed.

Will delete any existing ActivityParameter for this activity.

Deletes parameters key from Activity.

new_activity_parameters(data, group, overwrite=True)¶

Efficiently and correctly enter multiple parameters. Deletes all existing activity parameters for this group.

Will overwrite existing parameters in the same group with the same name, unless overwrite is false, in which case a ValueError is raised.

Input parameters must refer to a single, existing database.

group is the group name; will be autocreated if necessary. data should be a list of dictionaries:

[{
    'name': name of variable (unique),
    'database': activity database,
    'code': activity code,
    'amount': numeric value of variable (optional),
    'formula': formula in Python as string (optional),
    optional keys like uncertainty, etc. (no limitations)
}]

new_database_parameters(data, database, overwrite=True)¶

Efficiently and correctly enter multiple parameters. Deletes all existing database parameters for this database.

Will overwrite existing database parameters with the same name, unless overwrite is false, in which case a ValueError is raised.

database should be an existing database. data should be a list of dictionaries:

[{
    'name': name of variable (unique),
    'amount': numeric value of variable (optional),
    'formula': formula in Python as string (optional),
    optional keys like uncertainty, etc. (no limitations)
}]

new_project_parameters(data, overwrite=True)¶

Efficiently and correctly enter multiple parameters.

Will overwrite existing project parameters with the same name, unless overwrite is false, in which case a ValueError is raised.

data should be a list of dictionaries:

[{
    'name': name of variable (unique),
    'amount': numeric value of variable (optional),
    'formula': formula in Python as string (optional),
    optional keys like uncertainty, etc. (no limitations)
}]

recalculate()¶: Recalculate all expired project, database, and activity parameters, as well as exchanges.

remove_exchanges_from_group(group, activity, restore_original=True)¶

Takes a group and activity and removes all ParameterizedExchange objects from the group.

The restore_original parameter determines if the original amount values will be restored to those exchanges where a formula was used to alter the amount.

remove_from_group(group, activity, restore_amounts=True)¶

Remove activity from group.

Will delete any existing ActivityParameter and ParameterizedExchange for this activity.

Restores parameters key to this Activity. By default, restores amount value of each parameterized exchange of the Activity to the original value. This can be avoided by using the restore_amounts parameter.

rename_activity_parameter(parameter, new_name, update_dependencies=False)¶

Given a parameter and a new name, safely update the parameter.

Will raise a TypeError if the given parameter is of the incorrect type. Will raise a ValueError if other parameters depend on the given one and update_dependencies is False.

rename_database_parameter(parameter, new_name, update_dependencies=False)¶

Given a parameter and a new name, safely update the parameter.

Will raise a TypeError if the given parameter is of the incorrect type. Will raise a ValueError if other parameters depend on the given one and update_dependencies is False.

rename_project_parameter(parameter, new_name, update_dependencies=False)¶

Given a parameter and a new name, safely update the parameter.

Will raise a TypeError if the given parameter is of the incorrect type. Will raise a ValueError if other parameters depend on the given one and update_dependencies is False.

class bw2data.parameters.Group(*args, **kwargs)¶

DoesNotExist¶: alias of bw2data.parameters.GroupDoesNotExist

expire()¶: Set fresh to False

freshen()¶: Set fresh to True

save(*args, **kwargs)¶: Save this model instance. Will remove ‘project’ and database names from order.

class bw2data.parameters.ProjectParameter(*args, **kwargs)¶

Parameter set for a project. Group name is ‘project’.

Columns:

name: str, unique

formula: str, optional

amount: float, optional

data: object, optional. Used for any other metadata.

Note that there is no magic for reading and writing to data (unlike Activity objects) - it must be used directly.

DoesNotExist¶: alias of bw2data.parameters.ProjectParameterDoesNotExist

static dependency_chain()¶

Determine if `ProjectParameter parameters have dependencies within the group.

Returns:

[
    {
        'kind': 'project',
        'group': 'project',
        'names': set of variables names
    }
]

property dict¶: Parameter data as a standardized dictionary

static expired()¶: Return boolean - is this group expired?

is_deletable()¶: Perform a test to see if the current parameter can be deleted.

static load(group=None)¶: Return dictionary of parameter data with names as keys and .dict() as values.

static recalculate(ignored=None)¶

Recalculate all parameters.

ignored included for API compatibility with other recalculate methods - it will really be ignored.

static static(ignored='project', only=None)¶

Get dictionary of {name: amount} for all project parameters.

only restricts returned names to ones found in only. ignored included for API compatibility with other recalculate methods.

classmethod update_formula_parameter_name(old, new)¶

Performs an update of the formula of relevant parameters.

NOTE: Make sure to wrap this in an .atomic() statement!

class bw2data.parameters.DatabaseParameter(*args, **kwargs)¶

Parameter set for a database. Group name is the name of the database.

Columns:

database: str

name: str, unique within a database

formula: str, optional

amount: float, optional

data: object, optional. Used for any other metadata.

Note that there is no magic for reading and writing to data (unlike Activity objects) - it must be used directly.

DoesNotExist¶: alias of bw2data.parameters.DatabaseParameterDoesNotExist

static dependency_chain(group, include_self=False)¶

Find where each missing variable is defined in dependency chain.

If include_self is True will include parameters within the group as possible dependencies

Returns:

[
    {
        'kind': one of 'project', 'database', 'activity',
        'group': group name,
        'names': set of variables names
    }
]

property dict¶: Parameter data as a standardized dictionary

static expired(database)¶: Return boolean - is this group expired?

is_deletable()¶: Perform a test to see if the current parameter can be deleted.

static is_dependent_on(name)¶: Test if any database parameters are dependent on the given project parameter name.

static load(database)¶: Return dictionary of parameter data with names as keys and .dict() as values.

static recalculate(database)¶: Recalculate all database parameters for database, if expired.

save(*args, **kwargs)¶: Save this model instance

static static(database, only=None)¶: Return dictionary of {name: amount} for database group.

classmethod update_formula_database_parameter_name(old, new)¶

Performs an update of the formula of relevant parameters.

This method specifically targets database parameters used in database formulas

classmethod update_formula_project_parameter_name(old, new)¶

Performs an update of the formula of relevant parameters.

This method specifically targets project parameters used in database formulas

class bw2data.parameters.ActivityParameter(*args, **kwargs)¶

Parameter set for a group of activities.

Columns:

group: str

database: str

code: str. Code and database define the linked activity for this parameter.

name: str, unique within a group

formula: str, optional

amount: float, optional

data: object, optional. Used for any other metadata.

Activities can only have parameters in one group. Group names cannot be ‘project’ or the name of any existing database.

Activity parameter groups can depend on other activity parameter groups, so that a formula in group “a” can depend on a variable in group “b”. This dependency information is stored in Group.order - in our small example, we could define the following:

a = Group.get(name="a")
a.order = ["b", "c"]
a.save()

In this case, a variable not found in “a” would be searched for in “b” and then “c”, in that order. Database and then project parameters are also implicitly included at the end of Group.order.

Note that there is no magic for reading and writing to data (unlike Activity objects) - it must be used directly.

DoesNotExist¶: alias of bw2data.parameters.ActivityParameterDoesNotExist

static dependency_chain(group, include_self=False)¶

Find where each missing variable is defined in dependency chain.

Will also load in all parameters needed to resolve the ParameterizedExchanges for this group.

If include_self is True will include parameters within the group as possible dependencies

Returns:

[
    {
        'kind': one of 'project', 'database', 'activity',
        'group': group name,
        'names': set of variables names
    }
]

property dict¶: Parameter data as a standardized dictionary

static expired(group)¶: Return boolean - is this group expired?

is_deletable()¶: Perform a test to see if the current parameter can be deleted.

static is_dependency_within_group(name, group, include_order=False)¶

Determine if the given parameter name is a dependency within the given activity group.

The optional include_order parameter will include dependencies from groups found in the the Group.`order` field.

static is_dependent_on(name, group)¶: Test if any activity parameters are dependent on the given parameter name from the given group.

static load(group)¶: Return dictionary of parameter data with names as keys and .dict() as values.

static recalculate(group)¶: Recalculate all values for activity parameters in this group, and update their underlying Activity and Exchange values.

static recalculate_exchanges(group)¶: Recalculate formulas for all parameterized exchanges in group group.

save(*args, **kwargs)¶: Save this model instance

static static(group, only=None, full=False)¶

Get dictionary of {name: amount} for parameters defined in group.

only restricts returned names to ones found in only. full returns all names, including those found in the dependency chain.

classmethod update_formula_activity_parameter_name(old, new, include_order=False)¶

Performs an update of the formula of relevant parameters.

This method specifically targets activity parameters used in activity formulas

classmethod update_formula_database_parameter_name(old, new)¶

Performs an update of the formula of relevant parameters.

This method specifically targets database parameters used in activity formulas

classmethod update_formula_project_parameter_name(old, new)¶

Performs an update of the formula of relevant parameters.

This method specifically targets project parameters used in activity formulas

Utilities¶

utils.combine_methods(*ms)¶

Combine LCIA methods by adding duplicate characterization factors.

Args:

ms (one or more method id tuples): Any number of method ids, e.g. ("my method", "wow"), ("another method", "wheee").

Returns:

The new Method instance.

utils.download_file(directory='downloads', url=None)¶

Download a file and write it to disk in downloads directory.

If url is None, uses the Brightway2 data base URL. url should everything up to the filename, such that url + filename is the valid complete URL to download from.

Streams download to reduce memory usage.

Args:

filename (str): The filename to download.
directory (str, optional): Directory to save the file. Created if it doesn’t already exist.
url (str, optional): URL where the file is located, if not the default Brightway data URL.

Returns:

The path of the created file.

utils.natural_sort()¶: Sort the given list in the way that humans expect, e.g. 9 before 10.

utils.random_string()¶

Generate a random string of letters and numbers.

Args:

length (int): Length of string, default is 8

Returns:

A string (not unicode)

utils.recursive_str_to_unicode(encoding='utf8')¶: Convert the strings inside a (possibly nested) python data structure to unicode strings using encoding.

utils.uncertainify(distribution=None, bounds_factor=0.1, sd_factor=0.1)¶

Add some rough uncertainty to exchanges.

Warning

This function only changes exchanges with no uncertainty type or uncertainty type UndefinedUncertainty, and does not change production exchanges!

Can only apply normal or uniform uncertainty distributions; default is uniform. Distribution, if specified, must be a stats_array uncertainty object.

data is a LCI data dictionary.

If using the normal distribution:

sd_factor will be multiplied by the mean to calculate the standard deviation.
If no bounds are desired, set bounds_factor to None.
Otherwise, the bounds will be [(1 - bounds_factor) * mean, (1 + bounds_factor) * mean].

If using the uniform distribution, then the bounds are [(1 - bounds_factor) * mean, (1 + bounds_factor) * mean].

Returns the modified data.

Brightway2-data¶

Configuration¶

Projects¶

Base classes for metadata¶

Serialized Dictionary¶

Compound JSON dictionary¶

Pickled Dictionary¶

Metadata stores¶

databases¶

methods¶

normalizations¶

weightings¶

Mappings¶

mapping¶

geomapping¶

Data stores¶

DataStore¶

Inventory data backends¶

DatabaseChooser¶

Switching backends¶

Custom database backends¶

Default backend - databases stored in a SQLite database¶

Single file - each database in a single file¶

Version-control friendly - each database is a JSON file¶

Impact Assessment data stores¶

ImpactAssessmentDataStore¶

Method¶

Normalization¶

Weighting¶

User preferences¶

Parameters¶

Utilities¶

Brightway2

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