Configuration¶
As shown in Concepts and usage, a Computer
can be populated programmatically.
genno
can also read a simple configuration format in which settings and tasks are specified.
Overview¶
Ways to configure¶
Configuration is read through the Computer.configure()
method, or the top level genno.configure()
function.
Both methods accept either keyword arguments specifying the configuration values, or a path keyword argument that gives the path to a .json
or .yaml
-format file. For instance, the following are all equivalent:
# Create the computer before configuring from a JSON file
c = Computer()
c.configure(path="config-W.json")
# Create and configure from a YAML file in one step
c = Computer(path="config-W.yaml")
# Pass a data structure to configure()
info = dict(
general=[
dict(comp="product", key="W:a-b-c-d", inputs=["X::", "Y:d"], sums=True)
]
)
c = Computer()
c.configure(**info)
# Use the API to add a computation directly
c = Computer()
# add_product() infers the dimensions of W will be a-b-c-d
c.add_product("W", "X:a-b-c-d", "Y:d", sums=True)
…with the following file contents:
general:
- comp: product
key: W:a-b-c-d
inputs: ["X::", "Y:d"]
sums: true
{
"general": [
{
"comp": "product",
"key": "W:a-b-c-d",
"inputs": ["X::", "Y:d"],
"sums": true
}
]
}
Global- and specific configuration¶
Configuration is either global or specific to a certain Computer.
For instance, units: configuration is global; it affects all Computers, and can be set using either genno.configure()
or Computer.configure()
.
On the other hand, other configuration such as files: input adds tasks to a specific Computer, so it can only be set using Computer.configure()
.
- genno.configure(path: Optional[Union[pathlib.Path, str]] = None, **config)[source]¶
Configure
genno
globally.Modifies global variables that affect the behaviour of all Computers and computations. Configuration keys loaded from file are superseded by keyword arguments. Messages are logged at level
logging.INFO
if config contains unhandled sections.- Parameters
path (Path, optional) – Path to a configuration file in JSON or YAML format.
**config – Configuration keys/sections and values.
Custom handlers¶
The configuration file is divided into sections.
Generally each section contains a list of items, and each item is itself a mapping; see the built-in sections listed below.
genno.config
has one handler function for each section, and is extensible.
For instance, the genno compatibility module for pyam defines a handler for the section iamc:
; or the separate package ixmp
defines a handler for the sections filters:
and rename_dims:
.
The handles()
decorator can be used to mark a custom function that handles a custom configuration section:
from genno.config import handles
@handles("my-section")
def custom_handler(c: Computer, info):
print(f"Handle {info['name']}")
print(f" with inputs {repr(info['inputs'])}")
# Use a default value for one setting
key = info.get("key", "foo")
print(f"Output key: {key}")
# Manipulate the Computer instance `c` in some way
c.add("… etc.")
# This section is handled by genno's built-in handlers
general:
- comp: product
key: W:a-b-c-d
inputs: ["X::", "Y:d"]
sums: true
# These items are handled by the custom handler
my-section:
- name: item-a
inputs: [X, Y]
- name: item-b
key: bar
inputs: [W, Z]
- genno.config.handles(section_name: str, iterate: bool = True, discard: bool = True)[source]¶
Decorator to register a configuration section handler in
HANDLERS
.- Parameters
section_name (str) – The name of the configuration section to handle. Using a name already present in
HANDLERS
overrides that handler.iterate (bool, optional) – If
True
, the handler is called once for each item (either list item, or (key, value) tuple) in the section. IfFalse
, the entire section contents, of whatever type, are passed to tha handler.discard (bool, optional) – If
True
, configuration section data is discarded after the handler is called. IfFalse
, the data is retained and stored on the Computer.
- genno.config.HANDLERS: Dict[str, Any] = {'aggregate': <function aggregate>, 'alias': <function alias>, 'combine': <function combine>, 'default': <function default>, 'files': <function files>, 'filters': <function filters>, 'general': <function general>, 'iamc': <function iamc>, 'rename_dims': <function rename_dims>, 'report': <function report>, 'units': <function units>}¶
Registry of configuration section handlers.
- genno.config.STORE = {'cache_path', 'cache_skip'}¶
Configuration sections/keys to be stored with no action.
Specific sections¶
aggregate:
¶
- genno.config.aggregate(c: genno.core.computer.Computer, info)[source]¶
Handle one entry from the
aggregate:
config section.
Computer-specific configuration.
Invokes Computer.aggregate()
add tasks with computations.aggregate()
or computations.sum()
, computing sums across labels within one dimension of a quantity.
Each entry contains:
_quantities:
list of 0 or more keysQuantities to be aggregated. The full dimensionality of the key(s) is inferred.
_tag:
(str
)New tag to append to the keys for the aggregated quantities.
_dim:
(str
)Dimensions on which to aggregate.
Note the leading underscores. This is to distinguish these from all other keys, which are treated as group names. The corresponding values are lists of labels along the dimension to sum.
Example¶
aggregate:
- _quantities: [foo, bar]
_tag: aggregated
_dim: a
baz123: [baz1, baz2, baz3]
baz12: [baz1, baz2]
If the full dimensionality of the input quantities are foo:a-b
and bar:a-b-c
, then add_aggregate()
creates the new quantities foo:a-b:aggregated
and bar:a-b-c:aggregated
.
These new quantities have the new labels baz123
and baz12
along their a
dimension, with sums of the indicated values.
alias:
¶
- genno.config.alias(c: genno.core.computer.Computer, info)[source]¶
Handle one entry from the
alias:
config section.
Computer-specific configuration.
This section simply makes the output of one task available under another key.
alias:
"foo:x-y": "bar:x-y"
"baz:x-y": "bar:x-y"
Caching¶
Computer-specific configuration that controls the behaviour of functions decorated with Computer.cache()
.
cache_path:
(pathlib.Path
, optional)Base path for cache files. If not provided, defaults to the current working directory.
cache_skip:
(bool
, optional)If
True
, existing cache files are never used; files with the same cache key are overwritten.
combine:
¶
- genno.config.combine(c: genno.core.computer.Computer, info)[source]¶
Handle one entry from the
combine:
config section.
Computer-specific configuration.
Invokes Computer.add_combination()
to add tasks with computations.combine()
, computing a weighted sum of multiple Quantities.
Each item contains:
key:
Key for the new quantity, including dimensionality.
inputs:
(list
ofdict
)Inputs to the weighted sum. Each dict contains:
quantity:
(required)Key for the input quantity.
add_combination()
infers the proper dimensionality from the dimensions of key plus dimension to select on.select:
(dict
, optional)Selectors to be applied to the input quantity. Keys are dimensions; values are either single labels, or lists of labels. In the latter case, the sum is taken across these values, so that the result has the same dimensionality as key.
weight:
(int
, optional)Weight for the input quantity; default 1.
Example¶
For the following YAML:
combine:
- key: foo:a-b-c
inputs:
- quantity: bar
weight: -1
- quantity: baz::tag
select: {d: [d1, d2, d3]}
…add_combination()
infers:
default:
key/task¶
- genno.config.default(c: genno.core.computer.Computer, info)[source]¶
Handle the
default:
config section.
Computer-specific configuration.
This sets Computer.default_key
, used when get()
is called without arguments.
files:
input¶
- genno.config.files(c: genno.core.computer.Computer, info)[source]¶
Handle one entry from the
files:
config section.
Computer-specific configuration.
Invokes Computer.add_file()
to add computations.load_file()
.
If the path:
key is a relative path, it is resolved relative to the directory that contains the configuration file, else the current working directory.
files:
- path: ./input0.csv
key: d_check
# 'dims' argument can be supplied as list or dict
- path: ./input1.csv
key: input1-0
dims: [i, j_dim] # Omit extra dimension 'foo'
- path: ./input1.csv
key: input1-1
dims: {i: i, j_dim: j}
general:
¶
- genno.config.general(c: genno.core.computer.Computer, info)[source]¶
Handle one entry from the
general:
config section.
Computer-specific configuration.
This is, as the name implies, the most generalized section. Each item contains:
comp:
Refers to the name of a computation that is available in the namespace of
genno.computations
, or custom computations registered by compatibility modules or third-party packages. SeeComputer.add()
andComputer.get_comp()
. E.g. if “product”, thenComputer.add_product()
is called, which also automatically infers the correct dimensions for each input.key:
The key for the computed quantity.
inputs:
A list of keys to which the computation is applied.
args:
(dict
, optional)Keyword arguments to the computation.
add args:
(dict
, optional)Keyword arguments to
Computer.add()
itself.
report:
¶
- genno.config.report(c: genno.core.computer.Computer, info)[source]¶
Handle one entry from the
report:
config section.
Computer-specific configuration.
A ‘report’ is a concatenation of 1 or more other quantities.
Example¶
report:
- key: foo
members: [X, Y]
units:
¶
- genno.config.units(c: genno.core.computer.Computer, info)[source]¶
Handle the
units:
config section.
Global configuration.
Sub-keys:
replace:
(mapping of str -> str)Replace units before they are parsed by pint. Added to
REPLACE_UNITS
.define:
(str
)Multi-line block of unit definitions, added to the
pint
application registry so that units are recognized. See the pint documentation on defining units.
units:
replace:
dollar: USD
# YAML multi-line string
define: |-
pp = [person]
tiny = 0.1 millimetre