---
title: "Quick Start: Run K-Means Example"
---
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* This will be replaced by the TOC
{:toc}

This guide walks you through the steps of executing an example program ([K-Means clustering](http://en.wikipedia.org/wiki/K-means_clustering)) on Flink. On the way, you will see the a visualization of the program, the optimized execution plan, and track the progress of its execution.

## Setup Flink
Follow the [instructions](setup_quickstart.html) to setup Flink and enter the root directory of your Flink setup.

## Generate Input Data
Flink contains a data generator for K-Means.

~~~bash
# Assuming you are in the root directory of your Flink setup
mkdir kmeans
cd kmeans
# Run data generator
java -cp ../examples/flink-java-examples-{{ site.version }}-KMeans.jar:../lib/flink-dist-{{ site.version }}.jar \
  org.apache.flink.examples.java.clustering.util.KMeansDataGenerator \
  -points 500 -k 10 -stddev 0.08 -output `pwd`
~~~

The generator has the following arguments (arguments in `[]` are optional):

~~~bash
-points <num> -k <num clusters> [-output <output-path>] [-stddev <relative stddev>] [-range <centroid range>] [-seed <seed>]
~~~

The _relative standard deviation_ is an interesting tuning parameter. It determines the closeness of the points to randomly generated centers.

The `kmeans/` directory should now contain two files: `centers` and `points`. The `points` file contains the points to cluster and the `centers` file contains initial cluster centers.


## Inspect the Input Data
Use the `plotPoints.py` tool to review the generated data points. [Download Python Script](plotPoints.py)

~~~ bash
python plotPoints.py points ./points input
~~~ 

Note: You might have to install [matplotlib](http://matplotlib.org/) (`python-matplotlib` package on Ubuntu) to use the Python script.

You can review the input data stored in the `input-plot.pdf`, for example with Evince (`evince input-plot.pdf`).

The following overview presents the impact of the different standard deviations on the input data.

|relative stddev = 0.03|relative stddev = 0.08|relative stddev = 0.15|
|:--------------------:|:--------------------:|:--------------------:|
|<img src="{{ site.baseurl }}/page/img/quickstart-example/kmeans003.png" alt="example1" style="width: 275px;"/>|<img src="{{ site.baseurl }}/page/img/quickstart-example/kmeans008.png" alt="example2" style="width: 275px;"/>|<img src="{{ site.baseurl }}/page/img/quickstart-example/kmeans015.png" alt="example3" style="width: 275px;"/>|


## Start Flink
Start Flink and the web job submission client on your local machine.

~~~ bash
# return to the Flink root directory
cd ..
# start Flink
./bin/start-local.sh
# Start the web client
./bin/start-webclient.sh
~~~

## Inspect and Run the K-Means Example Program
The Flink web client allows to submit Flink programs using a graphical user interface.

<div class="row" style="padding-top:15px">
	<div class="col-md-6">
		<a data-lightbox="compiler" href="{{ site.baseurl }}/page/img/webclient_job_view.png" data-lightbox="example-1"><img class="img-responsive" src="{{ site.baseurl }}/page/img/webclient_job_view.png" /></a>
	</div>
	<div class="col-md-6">
		1. Open web client on  <a href="http://localhost:8080/launch.html">localhost:8080</a> <br>
		2. Upload the K-Mean job JAR file. 
			{% highlight bash %}
			./examples/flink-java-examples-*-KMeans.jar
			{% endhighlight %} </br>
		3. Select it in the left box to see how the operators in the plan are connected to each other. <br>
		4. Enter the arguments and options in the lower left box: <br>
            Arguments: <br>
			{% highlight bash %}
			file://<pathToFlink>/kmeans/points file://<pathToFlink>/kmeans/centers file://<pathToFlink>/kmeans/result 10
			{% endhighlight %}
			For example:
			{% highlight bash %}
			file:///tmp/flink/kmeans/points file:///tmp/flink/kmeans/centers file:///tmp/flink/kmeans/result 10
			{% endhighlight %}
            Options (optional): (set the default parallelims, e.g., to 4) <br>
			{% highlight bash %}
            -p 4
			{% endhighlight %}
	</div>
</div>
<hr>
<div class="row" style="padding-top:15px">
	<div class="col-md-6">
		<a data-lightbox="compiler" href="{{ site.baseurl }}/page/img/webclient_plan_view.png" data-lightbox="example-1"><img class="img-responsive" src="{{ site.baseurl }}/page/img/webclient_plan_view.png" /></a>
	</div>

	<div class="col-md-6">
		1. Press the <b>RunJob</b> to see the optimizer plan. <br>
		2. Inspect the operators and see the properties (input sizes, cost estimation) determined by the optimizer.
	</div>
</div>
<hr>
<div class="row" style="padding-top:15px">
	<div class="col-md-6">
		<a data-lightbox="compiler" href="{{ site.baseurl }}/page/img/jobmanager.png" data-lightbox="example-1"><img class="img-responsive" src="{{ site.baseurl }}/page/img/jobmanager.png" /></a>
	</div>
	<div class="col-md-6">
		1. Press the <b>Continue</b> button to start executing the job. <br>
		2. <a href="http://localhost:8080/launch.html">Open Flink's monitoring interface</a> to see the job's progress. (Due to the small input data, the job will finish really quick!)<br>
		3. Once the job has finished, you can analyze the runtime of the individual operators.
	</div>
</div>

## Shutdown Flink
Stop Flink when you are done.

~~~ bash
# stop Flink
./bin/stop-local.sh
# Stop the Flink web client
./bin/stop-webclient.sh
~~~

## Analyze the Result
Use the [Python Script](plotPoints.py) again to visualize the result.

~~~bash
cd kmeans
python plotPoints.py result ./result clusters
~~~

The following three pictures show the results for the sample input above. Play around with the parameters (number of iterations, number of clusters) to see how they affect the result.


|relative stddev = 0.03|relative stddev = 0.08|relative stddev = 0.15|
|:--------------------:|:--------------------:|:--------------------:|
|<img src="{{ site.baseurl }}/page/img/quickstart-example/result003.png" alt="example1" style="width: 275px;"/>|<img src="{{ site.baseurl }}/page/img/quickstart-example/result008.png" alt="example2" style="width: 275px;"/>|<img src="{{ site.baseurl }}/page/img/quickstart-example/result015.png" alt="example3" style="width: 275px;"/>|