Donut Chart Showing Most Common Tags for Items Sold

At the top-right corner of the dashboard, click Add Chart.

Select the sample_supplies.sales data source.

In the Select Data Source modal that appears:

1. Click the Project tab.

2. Click the name of the deployment that contains the sample data source.

3. Click the sample_supplies database. The database's data sources appear.

2. Click Select on the sales data source.

Select the Chart Type

1. In the Chart Type dropdown, select Circular.

2. Click Donut below the dropdown.

Add the desired fields to the proper encoding channels.

1. In the Fields section click the items field to expand the items object and view its properties.

2. Drag the items.tags field to the Label encoding channel. The Label encoding channel dictates which field to use when dividing the sections of the chart.

3. In the array reduction dropdown for the items array select Unwind array.

4. In the array reduction dropdowns for the tags select Array element by index. Using this option you can specify which element of the tags array to visualize.

5. Enter 0 for the Index input to only visualize the first element of the tags array. The first item tag is the most relevant tag to the item, so it should be the main concern in the visualiztion. This is the primary item tag.

   Note

   Selecting an array element by index also ensures the chart does not get overcrowded with less important tags as it would had you chosen to unwind the tags array rather than select a specific element.

6. Drag the id field to the Arc encoding channel.

7. In the Aggregate dropdown, select count. This option counts the occurrences of the first tag of each item and adds them to the chart.

Your chart should now look something like this:

click to enlarge

Copy the following filter into the Query input above the main chart display.

{ storeLocation: { $in: [ "Denver", "New York" ] }, 'items.price': {$gte: 1200} }

This filter specifies that Charts only visualizes item tags from items sold from either the Denver or New York store location where there was an item in the sale costing $1200 or more.

Click Apply to the right of the filter.

Your chart should now look something like this:

click to enlarge

Notice how the electronics tag now takes a larger slice of the distribution compared to when not using the filter. Based on this chart, notice that office and school are the two most common primary item tags from sales matching the filter.

Title your chart.

1. Hover over your chart title and click the pencil icon.

2. Copy the following into the chart title input:

   Frequency of Item Tags from Sales in Denver and New York with Price Threshold

3. Click the check mark to save your title.

Click Save and Close at the top-left of the chart builder view.

Your dashboard should now look something like this:

click to enlarge