Jan
21
2016

Difference between Heat map and Tree map

2This article explains the basic difference between heat maps and tree maps.

Theory/Information:

There are two very useful charts which help in analyzing data, heat maps and tree maps. Heat maps and tree maps are very insightful visualizations. However, many a times, there is a confusion between the two due to which analysts either use it wrongly or totally avoid using it. This article will help draw a clear line between heat maps and tree maps, thus enabling analysts to create better visualizations.

What are heat maps?

Heat maps is a type of data visualization in which up to two measures can be displayed by using size and color to express the values. It enables easy comparison of categorical values using color ranges. The layout is similar to a   text table with variations in values encoded as colors. In heat map, you can quickly see a wide array of information.

Heat maps are a good way to express many comparisons of a large number of set members to quickly identify outliers. In other words, Heat map is a type of visualization that is very apt to compare different categories.Two different measures can be compared at the same time with the help of a heat map. In a heat map, one measure can be assigned to the color and another measure can be assigned to the size. For example, in the below figure, we can see the sales by region for different product lines. The profit is represented by the color and ranges from red, for loss, to green, for profit. Similarly, the total sales is represented by the size. Hence, it is very easy to understand the performance of different products in different regions, in one glance, just by looking at the heat map.

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What are tree maps?

Tree maps are a relatively new feature in Tableau, first appearing in version 8.0. A tree map is designed to display hierarchical data as rectangles within rectangles. For each rectangle, two measures can be coded—one will affect    the size of a rectangle, and the other will affect color. Tree maps are ideal for showing hundreds or thousands of items in a single visualization simultaneously. If the number of items to be shown is very less,  then a tree map should not be preferred.

A slight disadvantage of tree maps in Tableau is that, as the number of items increase,the amount of space allocated for each item decreases. Hence, the area available to print the labels, become small.  As a result, usually, in a tree map almost all the squares or nodes will appear blank. This defect can be overcome by providing appropriate tooltips for each node. Like in heat maps, measures can be assigned to give different   colors and sizes to the nodes in the tree map. For example, in the below figure, assume that the profit (color) and sales (size) of products are given at a country and state-level. Bigger the size of the node, greater is the sales in that state. Similarly, greener the node, more is the profit in that state.

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About the Author: Sheeraja Rajakrishnan

I'm Sheeraja, a business analyst from Chennai, India, expertised in developing Tableau based visualizations to aid in business analyses. I am a quick learner and can communicate ideas to others, effectively. I am always ready to learn new technologies and like to share my knowledge with others.

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