# Copyright (c) 2019-2023 - for information on the respective copyright owner
# see the NOTICE file and/or the repository
# https://github.com/boschresearch/pylife
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
__author__ = "Johannes Mueller"
__maintainer__ = __author__
import pandas as pd
from .broadcaster import Broadcaster
from .data_validator import DataValidator
[docs]
class PylifeSignal(Broadcaster):
"""Base class for signal accessor classes.
Notes
-----
Derived classes need to implement the method `_validate(self, obj)`
that gets `pandas_obj` as `obj` parameter. This `validate()` method
must raise an Exception (e.g. AttributeError or ValueError) in case
`obj` is not a valid DataFrame for the kind of signal.
For these validation :func:`fail_if_key_missing()` and
:func:`get_missing_keys()` might be helpful.
For a derived class you can register methods without modifying the
class' code itself. This can be useful if you want to make signal
accessor classes extendable.
See also
--------
:func:`fail_if_key_missing()`
:func:`get_missing_keys()`
:func:`register_method()`
"""
_method_dict = {}
def __init__(self, pandas_obj):
"""Instantiate a :class:`signal.PyLifeSignal`.
Parameters
----------
pandas_obj : pandas.DataFrame or pandas.Series
"""
self._obj = pandas_obj
self._validate()
[docs]
@classmethod
def from_parameters(cls, **kwargs):
"""Make a signal instance from a parameter set.
This is a convenience function to instantiate a signal from individual
parameters rather than pandas objects.
A signal class like
.. code-block:: python
@pd.api.extensions.register_dataframe_accessor('foo_signal')
class FooSignal(PylifeSignal):
pass
The following two blocks are equivalent:
.. code-block:: python
pd.Series({'foo': 1.0, 'bar': 2.0}).foo_signal
.. code-block:: python
FooSignal.from_parameters(foo=1.0, bar=1.0)
"""
# TODO: better error handling
if len(kwargs) > 1 and hasattr(next(iter(kwargs.values())), '__iter__'):
obj = pd.DataFrame(kwargs)
else:
obj = pd.Series(kwargs)
return cls(obj)
[docs]
def keys(self):
"""Get a list of missing keys that are needed for a signal object.
Returns
-------
keys : pd.Index
a pandas index of keys
Raises
------
AttributeError
if `self._obj` is neither a `pandas.DataFrame` nor a `pandas.Series`
Notes
-----
If `self._obj` is a `pandas.DataFrame`, the `self._obj.columns` are returned.
If `self._obj` is a `pandas.Series`, the `self._obj.index` are returned.
"""
if isinstance(self._obj, pd.Series):
return self._obj.index
elif isinstance(self._obj, pd.DataFrame):
return self._obj.columns
raise AttributeError("An accessor object needs to be either a pandas.Series or a pandas.DataFrame")
[docs]
def get_missing_keys(self, keys_to_check):
"""Get a list of missing keys that are needed for a self._obj object.
Parameters
----------
keys_to_check : list
A list of keys that need to be available in `self._obj`
Returns
-------
missing_keys : list
a list of missing keys
Raises
------
AttributeError
if `self._obj` is neither a `pandas.DataFrame` nor a `pandas.Series`
Notes
-----
If `self._obj` is a `pandas.DataFrame`, all keys of
`keys_to_check` not found in the `self._obj.columns` are
returned.
If `self._obj` is a `pandas.Series`, all keys of
`keys_to_check` not found in the `self._obj.index` are
returned.
"""
return DataValidator().get_missing_keys(self._obj, keys_to_check)
[docs]
def fail_if_key_missing(self, keys_to_check, msg=None):
"""Raise an exception if any key is missing in a self._obj object.
Parameters
----------
self._obj : pandas.DataFrame or pandas.Series
The object to be checked
keys_to_check : list
A list of keys that need to be available in `self._obj`
Raises
------
AttributeError
if `self._obj` is neither a `pandas.DataFrame` nor a `pandas.Series`
AttributeError
if any of the keys is not found in the self._obj's keys.
Notes
-----
If `self._obj` is a `pandas.DataFrame`, all keys of
`keys_to_check` meed to be found in the `self._obj.columns`.
If `self._obj` is a `pandas.Series`, all keys of
`keys_to_check` meed to be found in the `self._obj.index`.
See also
--------
:func:`get_missing_keys`
:class:`stresssignal.StressTensorVoigt`
"""
DataValidator().fail_if_key_missing(self._obj, keys_to_check)
class _MethodCaller:
def __init__(self, method, obj):
self._method = method
self._obj = obj
def __call__(self, *args, **kwargs):
return self._method(self._obj, *args, **kwargs)
def __getattr__(self, itemname):
method = self._method_dict.get(itemname)
if method is None:
return super().__getattribute__(itemname)
return self._MethodCaller(method, self._obj)
@classmethod
def _register_method(cls, method_name):
def method_decorator(method):
if method_name in cls._method_dict.keys():
raise ValueError("Method '%s' already registered in %s" % (method_name, cls.__name__))
if hasattr(cls, method_name):
raise ValueError("%s already has an attribute '%s'" % (cls.__name__, method_name))
cls._method_dict[method_name] = method
return method_decorator
[docs]
def to_pandas(self):
"""Expose the pandas object of the signal.
Returns
-------
pandas_object : pd.DataFrame or pd.Series
The pandas object representing the signal
Notes
-----
The default implementation just returns the object given when
instantiating the signal class. Derived classes may return a modified
object or augmented, if they store some extra information.
By default the object is **not** copied. So make a copy yourself, if
you intent to modify it.
"""
return self._obj
def register_method(cls, method_name):
"""Registers a method to a class derived from :class:`PyifeSignal`
Parameters
----------
cls : class
The class the method is registered to.
method_name : str
The name of the method
Raises
------
ValueError
if `method_name` is already registered for the class
ValueError
if `method_name` the class has already an attribute `method_name`
Notes
-----
The function is meant to be used as a decorator for a function
that is to be installed as a method for a class. The class is
assumed to contain a pandas object in `self._obj`.
Examples
--------
.. code-block:: python
import pandas as pd
import pylife as pl
@pd.api.extensions.register_dataframe_accessor('foo')
class Foo(pl.signal.PyifeSignal):
def __init__(self, obj):
# self._validate(obj) could come here
self._obj = obj
@pl.signal.register_method(Foo, 'bar')
def bar(df):
return pd.DataFrame({'baz': df['foo'] + df['bar']})
>>> df = pd.DataFrame({'foo': [1.0, 2.0], 'bar': [-1.0, -2.0]})
>>> df.foo.bar()
baz
0 0.0
1 0.0
"""
return cls._register_method(method_name)