Database Reference
In-Depth Information
Figure 2-10. Area as a continuous data type (left); area as a discrete data type (right)
On the left, Area is plotted as a continuous axis (the Area “pill” on the left is green), while on
the right, each value for Area is given its own discrete column (the Area “pill” on the right is
blue). This illustrates the effect of changing data types in Tableau. In this case, both Area and
Population should probably be treated as continuous data types, but there are times when a
numerical data field (a dimension) should be treated as discrete, such as when the numbers
are actually codes for different categories (e.g., 0 = type 1, 1 = type 2, etc., where type 1 and
type 2 aren't in any particular order).
Calculated fields
The ability to create calculated fields from the fields in your workbook is a very useful fea-
ture of Tableau. For instance, what if you wanted to figure out which borough in our example
data table had the highest population density? The workbook already includes both popula-
tion and area, so all you need to do is divide them to answer your question. With calculated
fields, you can do just that. Right-click anywhere in the Dimensions or Measures area and se-
lect Create Calculated Field. Then, complete the Calculated Field dialog, as shown in
Fig-
