Flows and Runs

How to train/run a model and how to upload the results.

import openml
from sklearn import compose, ensemble, impute, neighbors, preprocessing, pipeline, tree

Train machine learning models

Train a scikit-learn model on the data manually.


This example uploads data. For that reason, this example connects to the test server at test.openml.org. This prevents the main server from crowding with example datasets, tasks, runs, and so on.

# NOTE: We are using dataset 68 from the test server: https://test.openml.org/d/68
dataset = openml.datasets.get_dataset(68)
X, y, categorical_indicator, attribute_names = dataset.get_data(
clf = neighbors.KNeighborsClassifier(n_neighbors=1)
clf.fit(X, y)

You can also ask for meta-data to automatically preprocess the data.

  • e.g. categorical features -> do feature encoding

dataset = openml.datasets.get_dataset(17)
X, y, categorical_indicator, attribute_names = dataset.get_data(
print("Categorical features: {}".format(categorical_indicator))
transformer = compose.ColumnTransformer(
    [('one_hot_encoder', preprocessing.OneHotEncoder(categories='auto'), categorical_indicator)])
X = transformer.fit_transform(X)
clf.fit(X, y)


Categorical features: [True, False, True, True, False, True, True, False, True, True, False, True, False, True, True, False, True, False, True, True]

Runs: Easily explore models

We can run (many) scikit-learn algorithms on (many) OpenML tasks.

# Get a task
task = openml.tasks.get_task(403)

# Build any classifier or pipeline
clf = tree.ExtraTreeClassifier()

# Run the flow
run = openml.runs.run_model_on_task(clf, task)



OpenML Run
Uploader Name: None
Metric.......: None
Run ID.......: None
Task ID......: 403
Task Type....: None
Task URL.....: https://test.openml.org/t/403
Flow ID......: 107914
Flow Name....: sklearn.tree.tree.ExtraTreeClassifier
Flow URL.....: https://test.openml.org/f/107914
Setup ID.....: None
Setup String.: Python_3.7.4. Sklearn_0.21.2. NumPy_1.17.2. SciPy_1.3.1. ExtraTreeClassifier(class_weight=None, criterion='gini', max_depth=None,
                    max_features='auto', max_leaf_nodes=None,
                    min_impurity_decrease=0.0, min_impurity_split=None,
                    min_samples_leaf=1, min_samples_split=2,
                    min_weight_fraction_leaf=0.0, random_state=38175,
Dataset ID...: 68
Dataset URL..: https://test.openml.org/d/68

Share the run on the OpenML server

So far the run is only available locally. By calling the publish function, the run is sent to the OpenML server:

myrun = run.publish()
# For this tutorial, our configuration publishes to the test server
# as to not pollute the main server.
print("Uploaded to http://test.openml.org/r/" + str(myrun.run_id))


Uploaded to http://test.openml.org/r/57252

We can now also inspect the flow object which was automatically created:

flow = openml.flows.get_flow(run.flow_id)


OpenML Flow
Flow ID.........: 107914 (version 5)
Flow URL........: https://test.openml.org/f/107914
Flow Name.......: sklearn.tree.tree.ExtraTreeClassifier
Flow Description: Automatically created scikit-learn flow.
Upload Date.....: 2019-08-19 17:16:42
Dependencies....: sklearn==0.21.2

It also works with pipelines

When you need to handle ‘dirty’ data, build pipelines to model then automatically.

task = openml.tasks.get_task(1)
features = task.get_dataset().features
nominal_feature_indices = [
    i for i in range(len(features))
    if features[i].name != task.target_name and features[i].data_type == 'nominal'
pipe = pipeline.Pipeline(steps=[
            ('Nominal', pipeline.Pipeline(
                    ('Imputer', impute.SimpleImputer(strategy='most_frequent')),
                            sparse=False, handle_unknown='ignore',
    ('Classifier', ensemble.RandomForestClassifier(n_estimators=10))

run = openml.runs.run_model_on_task(pipe, task, avoid_duplicate_runs=False)
myrun = run.publish()
print("Uploaded to http://test.openml.org/r/" + str(myrun.run_id))


Uploaded to http://test.openml.org/r/57253

Running flows on tasks offline for later upload

For those scenarios where there is no access to internet, it is possible to run a model on a task without uploading results or flows to the server immediately.

# To perform the following line offline, it is required to have been called before
# such that the task is cached on the local openml cache directory:
task = openml.tasks.get_task(6)

# The following lines can then be executed offline:
run = openml.runs.run_model_on_task(

# The run may be stored offline, and the flow will be stored along with it:

# They made later be loaded and uploaded
run = openml.runs.OpenMLRun.from_filesystem(directory='myrun')

# Publishing the run will automatically upload the related flow if
# it does not yet exist on the server.

Alternatively, one can also directly run flows.

# Get a task
task = openml.tasks.get_task(403)

# Build any classifier or pipeline
clf = tree.ExtraTreeClassifier()

# Obtain the scikit-learn extension interface to convert the classifier
# into a flow object.
extension = openml.extensions.get_extension_by_model(clf)
flow = extension.model_to_flow(clf)

run = openml.runs.run_flow_on_task(flow, task)


Try to build the best possible models on several OpenML tasks, compare your results with the rest of the class and learn from them. Some tasks you could try (or browse openml.org):

  • EEG eye state: data_id:1471, task_id:14951

  • Volcanoes on Venus: data_id:1527, task_id:10103

  • Walking activity: data_id:1509, task_id:9945, 150k instances.

  • Covertype (Satellite): data_id:150, task_id:218, 500k instances.

  • Higgs (Physics): data_id:23512, task_id:52950, 100k instances, missing values.

# Easy benchmarking:
for task_id in [115, ]:  # Add further tasks. Disclaimer: they might take some time
    task = openml.tasks.get_task(task_id)
    data = openml.datasets.get_dataset(task.dataset_id)
    clf = neighbors.KNeighborsClassifier(n_neighbors=5)

    run = openml.runs.run_model_on_task(clf, task, avoid_duplicate_runs=False)
    myrun = run.publish()
    print("kNN on %s: http://test.openml.org/r/%d" % (data.name, myrun.run_id))


kNN on diabetes: http://test.openml.org/r/57255

Total running time of the script: ( 0 minutes 21.865 seconds)

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