Measuring Distances Between Spatial Objects

1. Understanding the Distance Tool

The Distance tool is powerful yet has one simple requirement: the two spatial objects you want to measure between must exist in the same row of your dataset, in two separate fields. Its primary job is to calculate the distance between a "source" object and a "destination" object for every row in your data stream.

Let's begin by exploring the tool's core functionality.

As the article explained, the tool offers several key options. You can calculate:

• Straight-line distance: The direct path or "as the crow flies." This is the default and is a purely geometric calculation.
• Driving distance/time: A more practical measurement that uses street network data. This requires an Alteryx Spatial Data installation and license.
• Direction: You can also output the cardinal direction (e.g., NE) or the direction in degrees from the source to the destination.

The configuration panel lets you control all of these settings.

2. Data Preparation: Getting Your Objects in a Row

The most common challenge when using the Distance tool is preparing your data. Since the tool requires both spatial objects on the same row, you often need to perform a data manipulation step first.

There are two primary patterns for this.

Pattern 1: The Join/Append Method

This is used when you want to compare objects from two different datasets, or perform an "all-to-all" comparison. For example, calculating the distance from every customer to every store. You would use a Join tool (joining by record position if you want to compare row 1 to row 1, etc.) or an Append Fields tool (to create every possible combination).

Pattern 2: The Sequential Method

This pattern is used when you want to find the distance between consecutive points within the same list, such as the distance between each stop on a delivery route. The Join method doesn't work here. Instead, we need to get the location of the next stop onto the row of the current stop. The Multi-Row Formula tool is perfect for this.

Let's see how this advanced technique works.

This Multi-Row Formula technique is a powerful addition to your Alteryx toolset, especially for pathing and route analysis. The key is using an expression like [Row+1:Centroid] and ensuring the new field's data type is set to SpatialObj.

3. Hands-On Practice

Let's apply the sequential method to a practical problem.

Scenario: You have a dataset tracking a single delivery truck's route, ordered by stop sequence. You need to calculate the travel distance between each consecutive stop.

1. Open a new Alteryx workflow.
2. Use a Text Input tool and enter the following data for the delivery route:

3. Add a Create Points tool. Configure it to create a point object for each stop, using Longitude for the X Field and Latitude for the Y Field. Let's name the output field Centroid.

4. Add a Multi-Row Formula tool. We will configure it to create a new field that contains the Centroid of the next stop.

   • Click "Create New Field" and name it NextStopCentroid.
   • Change the Type to SpatialObj.
   • In the Expression box, enter [Row+1:Centroid]. This tells Alteryx to take the value from the Centroid field in the next row.
   • Leave "Group By" unchecked, as we only have one route.

5. Add a Distance tool after the Multi-Row Formula.

   • Set the Point or Centroid Source to your Centroid field.
   • Set the Point, Line or Polygon Destination to your NextStopCentroid field.
   • Under Output Distance, you can leave the units as Miles or change them to Kilometers. For this exercise, we'll use the default straight-line distance.

6. Add a Browse tool to the output and run your workflow.

In the results, you should see a new "DistanceMiles" field. It will show the distance between Stop 1 and 2, Stop 2 and 3, and so on. Notice that the last row has a null distance, because there is no "next stop" after the final one. You could use a Filter tool to remove this row if needed.

4. Beyond Point-to-Point

Finally, it's worth noting that the Distance tool can also measure the distance from a point to the nearest edge of a line or polygon. This is useful for answering questions like, "How far is this customer from the boundary of their sales territory?" or "How far is this house from the nearest river?" You can explore this in the "Use Case 2: Point to Polygon" section of the Tool Mastery | Distance article we looked at earlier.

Conclusion

You have now mastered the Distance tool, a cornerstone of spatial analysis in Alteryx. You've learned how it functions and, more importantly, how to perform the necessary data preparation to make it work for both all-to-all and sequential comparisons.

Key Takeaways:

• The Distance tool calculates the distance between a source and destination spatial object located on the same record.
• It supports straight-line (ellipsoidal) distance, as well as driving distance and time (with the appropriate data pack).
• Data preparation is key. Use a Join/Append for comparing separate datasets and a Multi-Row Formula for calculating distances between sequential points in a single dataset.

This lesson concludes the Spatial Data Fundamentals module. You are now equipped with the foundational skills to create, visualize, manipulate, and measure spatial data.

Preview of the Next Lesson:

We're now ready to move into the Applied Spatial Analytics module. In our next lesson, we will expand on the concept of drive time by using the Trade Area tool to create drive-time polygons. This is a powerful technique for visualizing market reach and is frequently used in site selection and business catchment analysis.