Heat Maps, Bar Chart and Line Charts in Tableau
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Heat Maps, Highlight Tables, Treemaps:
Comparing granular combinations of dimensions and measures can be done effectively with each of these charts.
To take a more visual approach to showing data than we might typically see in a crosstab, let’s consider a heat map. A heat map is a great way to compare categories using color and size. With this, you can compare two different measures.
The highlight table allows us to apply conditional formatting to a view. Tableau will automatically apply a color scheme in either a continuous or stepped array of colors from highest to lowest. It is great for comparing a field’s value within a row or column. Highlight tables can display one measure using a color gradient background to differentiate values.
Treemaps are a relatively new feature to Tableau, first appearing in version 8.0. They are very powerful visualizations, particularly for illustrating hierarchical (tree-structured) data and part-to-whole relationships. Because of their visual nature, treemapping is ideal for legibly showing hundreds or even thousands of items in a single visualization simultaneously. Treemaps effectively display larger dimension sets using color and size to display one or more dimensions and up to two measures.
Heatmap, highlight table, and treemap diagram :
These charts, and text tables, can also be used to replace Quick Filters on dashboards— providing more information in the same space that a multi-select filter would require.
Bar Chart, Stacked Bar, Side-by-Side Bars:
These charts facilitate one-to-many comparisons. Figure 3.6 includes examples of each.
Bar charts are the most effective way to compare values across dimensions— their linear nature making precise comparisons easy. The horizontal bar chart is a bit of a misnomer, because simply switching the axes with the Swap button in the Tableau toolbar will magically make a horizontal bar chart into a vertical bar chart! That’s actually not the crux of this chart – it is simply that the measures are presented in a stand-alone bar. Should your bars be horizontal or vertical? Well, it depends on space and your labels. If you have to turn your head to the left for a long period of time to read the labels on a vertical bar chart, then it’s best to swap your view.
Stacked bar charts should not be used when there are many different dimensions because they can be overwhelming if too many colors are plotted in each bar. The stacked bar chart is great for adding another level of detail inside of a horizontal bar chart. You can do this by adding another dimension to your horizontal bar chart that will further divide the measure into sub-groups.
Side-by-side bars provide another way to compare measures across and dimensions on a single axis.
Bar chart, stacked bar chart, and side-by-side bar chart diagram :
Line Charts For Time Series Analysis:
Time is relevant to almost every analysis. The ability to look forward and backward and drill down to weeks and days from months and years is fundamental. Tableau’s built-in date and time functions let you drag and drop to analyze time trends; drill into days, hours and seconds with a click; analyze time by day of the week; and easily perform time comparisons like year-over-year growth and moving averages.
Line charts are the most effective way to display time series data. One variable to consider when presenting time series is the treatment of time as a discrete (bucketed) entity or as a continuous (unbroken) series progression. Discrete line charts place breaks between time units (year, quarter, and month). Most people are familiar with time series charts that are presented in unbroken lines. Figure 3.2 presents a single measure (sales) using a discrete time series. Time is presented discretely by quarters within each year. Figure 3.7 provides three different time series charts that are plotting two measures with a continuous time axis.
Time series presented using a continuous time diagram :
The dual line chart presents two measures (sales and profit) using asynchronous axis ranges. Show Me assumes that dual axis charts are used to present values that are dissimilar and plots the marks using different axis ranges. The middle dual line chart, with synchronized axis, provides a better comparison of the relative values of sales and profit. The combination chart, using a bar for profit and line for sales, maintains asynchronous axis ranges, but the use of different mark types accentuates that there are different measures being plotted.