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Tips & Tricks and Common Pitfalls of KNIME

KNIME Analytics Platform is the strongest and most versatile free platform for drag and drops analytics, statistics, and machine learning. This tool is best for any data mining operations. Before checking the tips & tricks for KNIME first know the What is KNIME & its advantages.

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Tips and Tricks of KNIME

1. How to Enable Flow Variable Ports on a Node

Flow variables are used in the KNIME Analytics Platform to parameterize workflows when node settings need to be determined dynamically. They are carried along branches in workflow through data connections and explicit variable connections.

To enable flow variable ports in a node, you can either:

  • Right-click on the node to select the “Show Flow Variable Ports” option from the menu.

OR

  • Start a data connection at a flow variable port and drop it at the top left corner of a node

2. Keeping Your Data with Your Workflow

It’s a good idea to organize your workflows in Workflow Groups (folders) in your workspace. If you want to create a workflow group, right-click inside your local workspace in the KNIME Explorer view and select New Workflow Group. This creates a folder in the workspace directory for each workflow group. Once you have your files and workflows organized into groups, you can export the entire group to a KNIME Workflow Archive in “.knar” format to share with others.

3. How to Monitor the State of a Node

To monitor the state of a Node, you have to check out the KNIME Node Monitor view.

Go to View → Other → KNIME Views → Node Monitor. It gives you information about the selected item’s state along with other useful parameters. From the Node Monitor view, then, you can open the dropdown menu and let the Node Monitor display the different contents.

The Node Monitor can give you quite a lot of information about your node like-

  • You can use it to preview the output of a node without having to right-click on the node directly
  • You can have the Monitor display workflow variable values
  • You can keep a watch on how many times a node has executed, and how long it took to finish

4. Using Meta nodes for a Tidy Workflow

KNIME Analytics Platform relies on visual programming, thus making our work easier. However, the complexity of data analytics remains and can sometimes lead to quite complex and confusing workflows.

Wrapping huge, messy workflows inside a metanode is an excellent way to improve readability and understanding. Metanodes are nodes that contain other nodes. In the top-level workflow they appear like a single gray node but contain many nodes and even metanodes.

To create metanodes is very easy. You just have to select the nodes that you would like to group inside a metanode. Then right-click on it to click on the “Collapse into Wrapped Metanode” option. This makes your nodes disappear from your workflow and hides it inside the newly created wrapped metanode.

Wrapped metanodes have evolved from the simple metanodes. They can acquire a configuration window via Quickform nodes, their imports and outports can be renamed, and they can filter flow variables from the inside to the outside and vice versa. Also, wrapped metanodes allow for streaming functionality, which can improve I/O and run time.

5. Keyboard Shortcut to Open Wrapped Metanodes

Once you have created your wrapped metanode, you might want to review its content. The standard mouse-click method involves right-clicking the wrapped metanode and then selecting “Wrapped Metanode” → “Open”. This opens the content of the wrapped metanode in the workflow editor.

Alternatively, Ctrl + Double-click on the wrapped metanode also opens the wrapped metanode.

6. Viewing Content in the Workflow Editor

You can visualize two workflows or metanode content side by side inside the Workflow Editor of the KNIME Analytics Platform.

To revise the view to show a single editor, drag the supplementary editor tab to the tab panel in the main editor. Drop when you view a gray line in the tab panel in the main editor.

7. Fast Insertion of Nodes in a Workflow

If you pick a node from the Node Repository and drag it over an existing node in the workflow, you will see small white and blue boxes appearing inside the existing node. If you then drop the repository node in the workflow, it will replace the existing node.

If you double click the node in the Node Repository it directly displays in your Workflow Editor, already connected to the earlier selected node.

When dragging a node from the Node Repository to the connection between two nodes in the workflow, the node is automatically inserted between and connected to the two nodes.

8. Keyboard Shortcuts

The keyboard shortcuts for menu commands are listed, as you would expect, with the menu item. To view a full list of keyboard shortcuts, choose Help > Show Active Keybindings. From here you can view all the key bindings to commands, modify the bindings, and create your shortcuts.

Must Check: Top 10 Features of KNIME Analytics Platform

9. Change the Default Workflow Editor Settings

To change the default Workflow settings, go to File > Preferences > KNIME > KNIME GUI > Workflow Editor. It is the area where you can change the default node label if you wish newly created nodes to have other labels than Node 1, Node 2, etc. You can also change the grid size, or completely remove the grid in the background. You can alter the new default settings for single workflows any time using the Workflow Editor Settings.

10. Shortcut using Ctrl button

Pressing Ctrl, you can change the OK button in the configuration window to an “OK + Execute”.

Common Pitfalls of KNIME

  1. Old model ports created before KNIME 2.0 will not be restored. For example, an executed Color Manager which has a model output will be loaded as configured only because KNIME 2.0+ does not restore obsolete model ports. Subsequent nodes will also be reset and need to be executed.
  2. Special meta nodes specifically Cross-Validation and Looper do not report progress.
  3. Old tables comprising of the outdated bit vector definition will not be recognized by nodes using the new bit vector definition.
  4. Table View nodes, which were executed and saved with KNIME 1.3.x will be loaded as configured only i.e. concept of “auto-executable” has been completely revised since KNIME version 2.0.
  5. Old cross-validation and looper meta nodes will be reset when loaded.
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If you find this blog informative or interesting, then please check our high-quality KNIME Analytics Training. This certified training offers you high-quality videos and 24×7 online support.