How to Display the Custom Labels in a Gauge Chart

Problem:

In this demo, I don't understand the following:

1. What is the relation between the labels and the values?
2. What are the empty values for?
3. Why "640" and "750" labels are not shown?

   

Solution:
As you can see in the attached screenshot, the first label i.e. '300' represents the minimum value of the gauge. The same approach applies to the maximum value and everything in between. We use empty strings when we don't want to show that specific label. For example in this specific demo, we don't want to show 350, 400, 450, 500 and 550. "640" and "750" labels are not shown because the software automatically hides them to avoid congestion. We can force add them by adding maxItems property and setting itemsOverlap to true as you can see in the screenshot