Analytical Color Scales for Heat Maps

More sophisticated Color Scales to increase the analytical insights provided by Heat Maps or Choropleth Maps – a Guest Post by Ron Whale

The workbook posted with the recent article Geographical Flow Maps in Excel (Part 3 of 3) provided new color scales, I never published before. Truth be told, I did not develop these schemes. Ron Whale did. Ron generously agreed to share them here and he is even kind enough to explain the scales, their use cases and the value they add to analytical Heat Maps in today’s guest post. Enjoy.

Analytical Color Scales IntroJust a few months ago, I found this website and discovered a great Choropleth mapping spreadsheet. I really like the color mapping schemes that have been developed. As I worked through the program and played with the mapping colors, I began to understand that the colors could be used to highlight additional data details in the map.

So, I came up with a number of special purpose color schemes designed to enhance specific aspects of the data and added them in with some of the original color scales. As the color schemes grouped into different visual purposes, I named the new colors to better describe the type of data that would be highlighted when using that scale.

I thought I would share my twist on the color scales and will explain my thoughts about the different scale types below.

Analytical Color ScalesHere are the color scale types:

Contrast

A contrast is a multi-hue scale split in the middle of the scale.

Analytical Color Scales - ContrastsThese provide wonderful contrast on the map for excellent overall viewing. They are also good for data with positive and negative values or go/no go data.

No Scale

The original Light Scale is what I call a No Scale. A No Scale scheme is where there is no transition from light to dark colors to represent a corresponding sequential change in numeric values, just an unrelated color to indicate a “different” value.

Analytical Color Scales - No ScaleTo me it says, note there are boundaries of change on the map rather than note the amount of change.

Highlight

This scale is designed to highlight high or low values, with detail color steps in the selected end of the scale and only general combined categories in the non-highlighted end.

Analytical Color Scales - HighlightYou see detail where you want it but only broad categories where you have less interest.

Focus

The Focus scales are designed to show detail in the high or low end of the scale but completely ignore the other end containing non-focus data.

Analytical Color Scales - FocusIt reduces the color clutter on the map and draws the attention to locations where “the action is happening”.

Loaded

These scales highlight either the center of the scale (median) or the ends of the scale (outliers).

Analytical Color Scales - LoadedThe green and blue colors on the two ends of the Outlier scale help to discern high outliers from low outliers.

Pairs, Triplets, Quads, and Quints

I was intrigued by the original Pairwise color scale. To me, it shows diversity of map values really well, meaning a lot of counties have the dark green county color but they are generally not located next to the light green counties, which is the next closest value of the green color. Instead, dark green values were often located next to completely different colors, showing that the values from neighboring counties are not just a little different but a lot different.

I extended the Pairs idea to larger groupings which I called Triplets, Quads and Quints.

  • by using the Pairs color scale, I saw diversity between adjoining counties
  • by using the Triplets scale I suddenly saw larger area groupings and change across states and
  • by using the Quads and Quints scales, I saw detail within the states as values progressively moved across counties toward other states and areas.

Analytical Color Scales - Pairs, Triplets, Quads, QuintsYou can also think of pairs, triplets, quads, and quints as compressing two, three, four, and five adjacent bins to show a Low and High measure of similar general groupings. You will notice the Contrast color scales are already groupings of five or Quintuplets.

Stepped

Stepped color scales are where the color differences between steps are larger, and therefore, easier to distinguish between similar color hues on the map.

Analytical Color Scales - SteppedThe Blue Green Stepped scale is really two colors, but the blue color easily flows into the next color on the color continuum which is purple, thus giving even more distinction between steps but still providing the same general color. The Blue Stepped Red Tips color scale provides nice monochrome stepping with good color distinction and with red ends to show the extreme high and low ends of the scale. Gray Stepped is mostly for black and white printing.

Smear

Smear scales have smaller color steps that are not really meant to show a category of value, but to show the movement and direction of flow.

Analytical Color Scales - SmearSmears show general continuous change across the distance of the map while de-emphasizing the details. In other words, look at the big picture and not the small details.

I hope you like these optional color schemes presented here. I was quite surprised at the amount of information these color scales brought out in the map without having to change any data or re-sorting the data.

The process is not just a “flipping” of the colors. In a way, it is recompressing the category bins into new groupings and sub groupings to tell a new story without having to re-crunch the numbers.

Download Link

Download Analytical Color Scales (zipped Microsoft Excel Workbook, 12K)

About Ron

Ron Whale is a professional analyst with over 30 years of experience in programming, development, and visual reporting.  He is a big fan of Excel, demand forecasting, and mapping. Here is a link to his LinkedIn profile.

Robert’s Remarks

Many thanks go to Ron for generously sharing his brilliant color scales and for investing his precious time in explaining them in detail in this great guest article. This is highly appreciated. If you find Ron’s color schemes helpful, please drop him a line in the comment section.

What’s Next?

As Ron stated in his article, he developed the scales for using them on a Choropleth Map. That being said, they are also very helpful on a simple Heat Map of a cell range with numbers. One of the next posts will provide a solution for this.

Stay tuned.

Add a Comment

Your email address will not be published. Required fields are marked *