LUME-model

LUME-model holds data structures used in the LUME modeling toolset. Variables and models built using LUME-model will be compatible with other tools. LUME-model uses pydantic models to enforce typed attributes upon instantiation.

Requirements

• Python >= 3.9
• pydantic
• numpy

Install

LUME-model can be installed with conda using the command:

$ conda install lume-model -c conda-forge

Developer

A development environment may be created using the packaged dev-environment.yml file.

conda env create -f dev-environment.yml

Variables

The lume-model variables are intended to enforce requirements for input and output variables by variable type. For now, only scalar variables (floats) are supported.

Minimal example of scalar input and output variables:

from lume_model.variables import ScalarInputVariable, ScalarOutputVariable

input_variable = ScalarInputVariable(
    name="example_input",
    default=0.1,
    value_range=[0.0, 1.0],
)
output_variable = ScalarOutputVariable(name="example_output")

All input variables may be made into constants by passing the is_constant=True keyword argument. Value assingments on these constant variables will raise an error message.

Models

The lume-model base class lume_model.base.LUMEBaseModel is intended to guide user development while allowing for flexibility and customizability. It is used to enforce LUME tool compatible classes for the execution of trained models.

Requirements for model classes:

• input_variables: A list defining the input variables for the model. Variable names must be unique. Required for use with lume-epics tools.
• output_variables: A list defining the output variables for the model. Variable names must be unique. Required for use with lume-epics tools.
• evaluate: The evaluate method is called by the serving model. Subclasses must implement this method, accepting and returning a dictionary.

Example model implementation and instantiation:

from lume_model.base import LUMEBaseModel
from lume_model.variables import ScalarInputVariable, ScalarOutputVariable


class ExampleModel(LUMEBaseModel):
    def evaluate(self, input_dict):
        output_dict = {
            "output1": input_dict[self.input_variables[0].name] ** 2,
            "output2": input_dict[self.input_variables[1].name] ** 2,
        }
        return output_dict


input_variables = [
    ScalarInputVariable(name="input1", default=0.1, value_range=[0.0, 1.0]),
    ScalarInputVariable(name="input2", default=0.2, value_range=[0.0, 1.0]),
]
output_variables = [
    ScalarOutputVariable(name="output1"),
    ScalarOutputVariable(name="output2"),
]

m = ExampleModel(input_variables=input_variables, output_variables=output_variables)

Configuration files

Models and variables may be constructed using a YAML configuration file. The configuration file consists of three sections:

• model (optional, can alternatively pass a custom model class into the model_from_yaml method)
• input_variables
• output_variables

The model section is used for the initialization of model classes. The model_class entry is used to specify the model class to initialize. The model_from_yaml method will attempt to import the specified class. Additional model-specific requirements may be provided. These requirements will be checked before model construction. Model keyword arguments may be passed via the config file or with the function kwarg model_kwargs. All models are assumed to accept input_variables and output_variables as keyword arguments.

For example, m.dump("example_model.yml") writes the following to file

model_class: ExampleModel
input_variables:
  input1:
    variable_type: scalar
    default: 0.1
    is_constant: false
    value_range: [0.0, 1.0]
  input2:
    variable_type: scalar
    default: 0.2
    is_constant: false
    value_range: [0.0, 1.0]
output_variables:
  output1: {variable_type: scalar}
  output2: {variable_type: scalar}

and can be loaded by simply passing the file to the model constructor:

from lume_model.base import LUMEBaseModel


class ExampleModel(LUMEBaseModel):
    def evaluate(self, input_dict):
        output_dict = {
            "output1": input_dict[self.input_variables[0].name] ** 2,
            "output2": input_dict[self.input_variables[1].name] ** 2,
        }
        return output_dict


m = ExampleModel("example_model.yml")

PyTorch Toolkit

In the same way as the KerasModel, a PyTorchModel can also be loaded using the lume_model.utils.model_from_yaml method, specifying PyTorchModel in the model_class of the configuration file.

model:
  kwargs:
    model_file: /path/to/california_regression.pt
  model_class: lume_model.torch.PyTorchModel
  model_info: path/to/model_info.json
  output_format:
    type: tensor
  requirements:
    torch: 1.12

In addition to the model_class, we also specify the path to the pytorch model (saved using torch.save()) and additional information about the model through the model_info.json file such as the order of the feature names and outputs of the model:

{
    "train_input_mins": [
        0.4999000132083893,
        ...
        -124.3499984741211
    ],
    "train_input_maxs": [
        15.000100135803223,
        ...
        -114.30999755859375
    ],
    "model_in_list": [
        "MedInc",
        ...
        "Longitude"
    ],
    "model_out_list": [
        "MedHouseVal"
    ],
    "loc_in": {
        "MedInc": 0,
        ...
        "Longitude": 7
    },
    "loc_out": {
        "MedHouseVal": 0
    }
}

The output_format specification indicates which form the outputs of the model's evaluate() function should take, which may vary depending on the application. PyTorchModels working with the LUME-EPICS service will require an OutputVariable type, while Xopt requires either a dictionary of float values or tensors as output.

It is important to note that currently the transformers are not loaded into the model when using the model_from_yaml method. These need to be created separately and added either:

• to the model's kwargs before instantiating

import torch
import json
from lume_model.torch import PyTorchModel

# load the model class and kwargs
with open(f"california_variables.yml","r") as f:
  yaml_model, yaml_kwargs = model_from_yaml(f, load_model=False)

# construct the transformers
with open("normalization.json", "r") as f:
  normalizations = json.load(f)

input_transformer = AffineInputTransform(
    len(normalizations["x_mean"]),
    coefficient=torch.tensor(normalizations["x_scale"]),
    offset=torch.tensor(normalizations["x_mean"]),
)
output_transformer = AffineInputTransform(
    len(normalizations["y_mean"]),
    coefficient=torch.tensor(normalizations["y_scale"]),
    offset=torch.tensor(normalizations["y_mean"]),
)

model_kwargs["input_transformers"] = [input_transformer]
model_kwargs["output_transformers"] = [output_transformer]

model = PyTorchModel(**model_kwargs)

• using the setters for the transformer attributes in the model.

# load the model
with open("california_variables.yml", "r") as f:
  model = model_from_yaml(f, load_model=True)

# construct the transformers
with open("normalization.json", "r") as f:
  normalizations = json.load(f)

input_transformer = AffineInputTransform(
    len(normalizations["x_mean"]),
    coefficient=torch.tensor(normalizations["x_scale"]),
    offset=torch.tensor(normalizations["x_mean"]),
)
output_transformer = AffineInputTransform(
    len(normalizations["y_mean"]),
    coefficient=torch.tensor(normalizations["y_scale"]),
    offset=torch.tensor(normalizations["y_mean"]),
)

# use the model's setter to add the transformers. Here we use a tuple
# to tell the setter where in the list the transformer should be inserted.
# In this case because we only have one, we add them at the beginning
# of the lists.
model.input_transformers = (input_transformer, 0)
model.output_transformers = (output_transformer, 0)