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6. Combo Charts
Combo charts allow you to combine a bar chart and a line chart on the same visual, even if their numeric scales vary considerably. We’ll see the different types of combo chart in this lesson.
- Combo Charts combine a line chart and a column chart
- The column chart can be stacked or clustered
- This is useful when you want to graph two variables that have different numeric scales
So far, we've looked at two main chart families, bar charts and line charts.
In this lesson, we'll look at how to combine bar and line charts into a single visualization. To illustrate why this can be useful, let's create a new page in our report and name it combo charts.
Suppose we want to examine the relationship between the revenue generated and number of users. Specifically, we want to see if there are any differences in revenue generated for user between the different parts of the country. This time, we'll analyze at the subregion level. We'll start by creating a new chart of revenue by subregion.
Next, we'll add the number of users to the values well and enlarge the chart.
We can see that the bars for users are far too small to be useful.
This is because each subregion has several million dollars of revenue but at most, 127,000 users.
A single numeric axis simply does not work for both variables. To fix this, we'll create a combo chart.
We can combine a line chart with a stacked, or clustered column chart. We'll select line and clustered column chart. If we've looked at the field wells, we can see that we now have the option of column values and line values.
We'll drag the number of users to the line values well and see if the number of users becomes a line with it's own y-axis on the right side of the visualization. We can now, easily, compare the revenue and number of users by subregion.
It's immediately clear that both line and columns follow a very similar trend, implying there is no major difference in the average revenue per user by subregion. If we look back over the visualizations pane, we can see that there is a new well called column series. This effectively functions as a legend for the column chart.
Lets drag the stack field to this well.
The column chart is clustered by stack, however, it's not that easy to read. Unfortunately, Power BI determines the width of each column according to the total number of different values in the model. This means, that the column width is determined by the total number of stacks. Not the number of stacks in each subregion. To make this chart easier to understand, lets switch to a line and stacked column chart. This switched the column chart to a stacked chart. Which we've seen in previous lessons. If you find clustered column charts produced columns that are too narrow then switching to a stacked bar chart like this may help. As we can see, the combo chart is useful when you want to compare variables with different scales on a single visualization. We've now covered the full range of bar, column, and line charts avaliable in Power BI. In the next few lessons, we'll look at slicers and filters, possibly the most common tools you'll use along-side your visualizations.