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4. Legends and Tooltips
Legends and tooltips provide more information to viewers of your charts. Legends divide a bar or line by category, while tooltips provide more information when you mouse over part of a chart.
- Legends create several categories based on a given field in the data model
- On a chart, each category is displayed with a different color
- Legends should be used when the number of categories is relatively small
- Tooltips are visible when you mouse over a chart element such as a bar, column or line
- Tooltips display numeric values of the data that can be seen on the chart
- You can also add fields to the tooltip that are not featured on the chart
- This is useful when you have a field that does not fit with the data on the chart
Power BI offers two options that allow you to display more information within your visuals: legends and tooltips.
We've already seen both of these in action, but in this lesson we'll look at them in more detail.
As we've already seen, a legend can be used to break down a field by another field.
In our case, we've broken down revenue by subregion.
We can see that each subregion has a different color with the actual legend itself located at the top of the graph. Note that in this instance, the legend is too wide to fit on the visual so we must click the arrow to scroll through the remaining entries.
As you can imagine, legends are the most useful when analyzing a relatively small number of categories.
In Power BI, legends have their own well in the fields section of the visualizations pane.
To create a legend, we drag the relevant field to this well.
Only one field can be used to create a legend for each visual.
Once we've selected our legend, the formatting options become available in the formatting section of the visualizations pane. Let's select the formatting icon, and select legend.
Here, we have familiar options for altering size, color, and font of the legend text.
We also have the ability to move the legend around the visual.
We can move it to any side of the chart and we can ensure that it's centered as well.
We won't make any changes to the legend formatting at the moment, so we'll collapse the drop down. Tooltips provide more detail to data points on the visual.
Tooltips can be viewed in any kind of chart by hovering over a data point.
As we hover the mouse over the revenue by region chart, a tooltip for a specific bar displays the name of the region and the total revenue for that region.
In the revenue by region and subregion chart, the tooltip shows the region, subregion, and revenue for the subregion.
Tooltips are handy when you want to know the exact numerical value of a data point without having to resort to tables.
You may have also spotted a tooltips well in our visualizations pane.
Note that this well does not currently have an associated field yet we still have a functioning tooltip. This is because Power BI automatically creates a tooltip for every visualization featuring all the fields we added to the visual.
You should be aware that you can not remove these fields or change how they're labeled in the tooltip.
As such, if you expect your readers to make use of tooltips, you should make sure that your field names are easy to understand. We can add more fields to the tooltip by dragging them to the tooltips well. Let's say we want our tooltip to tell us how many companies there are in each region.
We can do this by selecting the visual, and then dragging company name to the tooltips well.
We then need to modify the tooltip by clicking the arrow next to first company name, and selecting count.
Now when we hover over each bar, we can see the number of companies in that region.
For example, the Northeast region has 334 companies, while the South region has 343.
Despite having more companies, the South region has slightly less revenue.
This tells us that the companies in the South have a lower average revenue than companies in the Northeast.
As you can see, legends and tooltips provide another layer of insight that's easily accessible to our audience.
In the next lesson, we'll move on and look at some of the other types of visualizations available in Power BI.