Tutorial¶
ONNX Runtime provides an easy way to run machine learned models with high performance on CPU or GPU without dependencies on the training framework. Machine learning frameworks are usually optimized for batch training rather than for prediction, which is a more common scenario in applications, sites, and services. At a high level, you can:
Train a model using your favorite framework.
Convert or export the model into ONNX format. See ONNX Tutorials for more details.
Load and run the model using ONNX Runtime.
In this tutorial, we will briefly create a pipeline with scikit-learn, convert it into ONNX format and run the first predictions.
Step 1: Train a model using your favorite framework¶
We’ll use the famous iris datasets.
from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
iris = load_iris()
X, y = iris.data, iris.target
X_train, X_test, y_train, y_test = train_test_split(X, y)
from sklearn.linear_model import LogisticRegression
clr = LogisticRegression()
clr.fit(X_train, y_train)
Step 2: Convert or export the model into ONNX format¶
ONNX is a format to describe the machine learned model. It defines a set of commonly used operators to compose models. There are tools to convert other model formats into ONNX. Here we will use ONNXMLTools.
from onnxmltools import convert_sklearn
from onnxmltools.utils import save_model
from onnxmltools.convert.common.data_types import FloatTensorType
initial_type = [('float_input', FloatTensorType([1, 4]))]
onx = convert_sklearn(clr, initial_types=initial_type)
save_model(onx, "logreg_iris.onnx")
Step 3: Load and run the model using ONNX Runtime¶
We will use ONNX Runtime to compute the predictions for this machine learning model.
import onnxruntime as rt
sess = rt.InferenceSession("logreg_iris.onnx")
input_name = sess.get_inputs()[0].name
pred_onx = sess.run([label_name], {input_name: X_test.astype(numpy.float32)})[0]
Target opset¶
By default, the converters uses the latest version of operators defined in the installed onnx package but that can be changed by specifying target_opset to a lower version when calling the conversion function.
