Tableau: Visualize Colors

Tableau Default Palettes

The link to the video of implementing the Tableau instructions for this section follows.

Create the Bar Chart

We begin with territory already covered, creating the standard bar chart. Once again, we will return to the employee data set and create the bar chart for the average salary across departments of the company. Open the employee data set Excel file, drag the department variable Dept over to the Columns shelf and the created Count variable over to the Rows shelf. Our bar chart emerges in Figure 1 with the default darkish blue bar colors.

Figure 1: Bar chart of Employee variable Dept with default bar color.

There is one missing value for department in the data set, which Tableau renders as Null. As an option, remove the Null value. Drag the Dept name to to the Filters card, which then opens the dialogue box in Figure 2 that lets us retain or delete levels of the categorical variable as we wish.

Figure 2: As an option, filter out the NULL value for missing data.

With the Null value removed, the five remaining non-missing levels of Department appear in the bar chart, which displays the average salary across the five departments, Figure 3.

Figure 3: Bar chart of Dept with the Null value removed.

Default Quantitative Palette

There is no consistency of opinion as to whether the bars in a categorical variable bar chart should be the same color or vary in color. An argument for retaining the same color across bars is that different bar colors do not distract the viewer in different ways for the different bars. An argument for different bar colors is that the bar graph is more attractive and visually appealing, perhaps to longer hold the viewers attention.

Display the bars of the bar chart in the default tableau qualitative ballet is straightforward. Simply drag the Dept variable name over to the Color mark. The result is shown in Figure 4.

Figure 4: Default Tableau quantitative palette.

Additional Palettes

Tableau has several dozen built-in and available qualitative palettes. To access these palettes, double-click on the Color mark, which results in the Edit Colors prompt shown in Figure 5.

Figure 5: Edit Colors dialogue box from clicking on the Colors mark.

Clicking on Edit Colors leads to the access of the built-in palettes. The dropped down menu under Select Color Palette: displays the available palettes. The default palette is referenced by the name Automatic. This palette can accommodate the10 different colors shown in Figure 6. Also displayed are the levels of the categorical variable with their assigned colors,

If going to choose another palette, after selecting that palette from the drop-down, click Assign Palette and then click Apply.

Highlight a Bar

Another way to display a visualization, such as a bar chart, is to highlight one specific level of the categorical variable. Usually, the non-highlighted bars are displayed in a neutral color, such as a light-medium gray. In this example, select the Gray Warm` palette. Select one of the non-highlighted levels, here of Dept, then click on the desired color in the palette, shown in Figure 7.

Figure 7: Assign a light gray color to the Sales bar.

Repeat that procedure for all non-highlighted bars, resulting in Figure 8.

Figure 8: All bars assigned the same color except the bar to be highlighted, ADMN.

Click on Assign Palette and then Apply to obtain the bar chart shown in Figure 9.

Figure 9: The bar chart with the ADMN bar highlighted.

Of course, this procedure could be repeated for each level of the categorical variable, with each corresponding bar highlighted a different color that does not conform to any built-in palettes.

Add a Custom Palette

The link to the video of implementing the Tableau instructions for adding a custom palette follows.

Video: Tableau Custom Palette. [5:03]

Create the Palette

In this example, we add the lessR qualitative palette to Tableau. First, we need the palette obtained from the lessR function getColors().

pal <- getColors()
pal

[1] "#4398D0" "#B28B2A" "#5FA140" "#D57388" "#9A84D6" "#00A898"
    "#C97E5B" "#909711" "#00A3BA" "#D26FAF" "#00A76F" "#BD76CB"

How do we enter this palette into Tableau? Within your Documents folder is the My Tableau Repository folder. Inside that folder, find the Preferences.tps file. That file is in XML format, a generalization of HTML that allows for custom tags. We will need to add some HTML-like instructions in a text editor such as RStudio. If not modified before, opening that file in RStudio shows the following in Figure 10.

Figure 10: The unmodified Preferences.tps file.

The first task is to insert the begin <preferences> and close </preferences> tags, resulting in the following layout, shown in Figure 11.

Figure 11: Add the preferences opening and closing tags.

Between the preferences tags create a new color-palette tags as follows: followed by the closing tag shown in Figure 12.

Figure 12: Add the opening and closing color-palette tags.

Whatever you specify for the name becomes the palette name in the Tableau system. Also, the specified value of type is "regular", which denotes the creation of a categorical color palette.

Between the color-palette tags, now define the color palette. For each color in your palette, create an open and closed color tag, with its defining hexidecimal code inbetween. For example, a fully formed color palette looks like this, here with the first six colors from the lessR default quantitative palette as in Figure 13.

Figure 13: Add the opening and closing color tags for each color in the new palette.

When your color palette is complete, save the Preferences.tps file and restart Tableau.

Access the Palette

When back in Tableau, you will be able to locate your custom palette at the bottom of the drop-down list of palettes. As before, to access the palettes, click on the Colors mark and then the Select Color Palette: drop-down menu as in Figure 14.

Figure 14: Access the added palette from the Edit Colors dialogue by clicking on the Colors mark.

Select at the bottom of the palette list the defined custom palette, here named lessR palette, as shown in Figure 15.

Figure 15: The custom lessR palette is assigned to the five bars of Dept.

Click on Assign Palette and then Apply to display the Dept bar chart in native lessR colors shown in Figure 16.