Quick Start

Install tsfresh

As the compiled tsfresh package is hosted on pypy you can easily install it with pip

pip install tsfresh

Dive in

Before boring yourself by reading the docs in detail, you can dive right into tsfresh with the following example:

We are given a data set containing robot failures as discussed in [1]. Each robot records time series from six different sensors. For each sample denoted by a different id we are going to classify if the robot reports a failure or not. From a machine learning point of view, our goal is to classify each group of time series.

To start, we load the data into python

from tsfresh.examples import load_robot_execution_failures
timeseries, y = load_robot_execution_failures()

and end up with a pandas.DataFrame timeseries having the following shape

  id time a b c d e f
0 1 0 -1 -1 63 -3 -1 0
1 1 1 0 0 62 -3 -1 0
2 1 2 -1 -1 61 -3 0 0
3 1 3 -1 -1 63 -2 -1 0
4 1 4 -1 -1 63 -3 -1 0
... ... ... ... ... ... ... ... ...

The first column is the DataFrame index and has no meaning here. There are six different time series (a-f) for all different robots that are denoted by the ids column.

On the other hand, y contains the information which id belongs to a failure and which not:

1 0
2 0
3 0
4 0
5 0
... ...

Here, for the samples with ids 1 to 5 no failure was reported.

In the following we illustrate the time series of the sample id 3 reporting no failure:

the time series for id 3 (no failure)

And for id 20 reporting a failure:

the time series for id 20 (failure)

Now tsfresh comes into place. It allows us to automatically extract over 1200 features from those six different time series.

First we extract all features:

from tsfresh import extract_features
extracted_features = extract_features(timeseries, column_id="id", column_sort="time")

You end up with all extracted features, which are more than 1200 different. We will now remove all NaN values and select only the relevant features

from tsfresh import select features
from tsfresh.utilities.dataframe_functions import impute

impute(extracted_features)
features_filtered = select_features(extracted_features, y)

Only around 300 features were classified as relevant enough.

Further, you can even perform the extraction, imputing and filtering at the same time with the tsfresh.convenience.extract_relevant_features() function:

from tsfresh import extract_relevant_features

X_filtered = extract_relevant_features(df, y, column_id='id', column_sort='time')

You can now use these features features_filtered in conjunction with y to train your model. Please see the robot_failure_example.ipynb Jupyter Notebook in the folder named notebook. In this notebook a RandomForestClassifier is trained on the extracted features.

References

[1]http://archive.ics.uci.edu/ml/datasets/Robot+Execution+Failures