Calculate Length

We aim to calculate the length of the security fence surrounding public playgrounds in Seattle using a dataset containing information about city public spaces.

To use the workflow, download and run it on the KNIME Analytics Platform. For optimal performance using the Geospatial Analytics extension, make sure you are using version 4.7.4 or higher.

The input data has been saved in the workflow data area, simply execute the components "Read Dataset" to obtain the necessary data.

In this scenario, the city council is considering replacing the security fences for all public playgrounds. To estimate the total cost, we need to determine the length of these playground areas.

The input data has been saved in the workflow data area, simply execute the component "Read Dataset" to obtain the necessary data.

The next step involves filtering out only public spaces that are playgrounds. This can be achieved by labelling each entry with the Rule Engine node and filtering everything using the Row filter node.

One crucial step is configuring the geometry projection to calculate meters' length accurately. We use the Equal Earth projection to prevent area distortions.

We use the Length node to determine the length of the playground's polygon in meters. It's important to note that the dataset already includes a column called "Shape_Length" with measurements in feet. However, we are creating a new column for educational purposes.

With the Math Formula node, we calculate the cost of the new security fence for each playground.

Then, we plot the results using the Geospatial view node. By hovering over the coloured areas, you can see information about the playground name, area length in meters, and the cost of the new security fence.

External resources

• Public Spaces Seattle