We will cover 3 ways how to add Data Studio Annotations:

Adding by using a calculated field

Using a CSV file and data source blending

Using Google Sheets, some optional pivoting and data source blending

1. Add Annotation by using calculated field

To get going, Edit your data source (with the Pencil icon ), when you see your current fields, find and choose Add a field, name it after your event eg: Google Algorithm Update and add the below formula:

Section to add a calculated field to a datasource using a CASE formula

Timestamp is an existing field in our primary dataset. Please be aware that you might have a different field, or date format, and you need to experiment a bit with it. You might have 2019–09–30 or 20190930 so do retries until you get data on your screen.

Now you have your new field in the Available Fields to choose for your custom annotation.

Add the newly created field to the chart. Whenever you are required to choose an aggregation choose SUM.

You will notice no immediate visible change.

Customizing the Style

You need to customize settings on the Style tab for your chart.

By having the above steps done, you ensure that you will get the annotation to display as a bar that uses the whole 100% high if you set axis max to 1. Also you might get some awkward grid lines if you omit to set Custom Tick interval 1, so make sure all the above steps are done. In the Style tab you can customize the color of the bar as well.

The width of the bar is automatically inferred based on the data-points-width, so if you have a large days span it will be very thin. In this situation you might want to add a date range match for your custom field to spawn multiple days, and be wider on the chart.

2. Use a CSV for annotations source

While calculated field allows quick experiment with Data Studio Annotations, it’s not productive when you need to apply on multiple charts, reports and you need to carry forward on weekly basis your annotation definition. For this, the best is if you store your Annotation definitions in a CSV file or Google Sheet. I named this section CSV, but it can be a Google Sheet as well.

To make Annotations work from a tabular dataset, you have to ensure the following column structure.

Organize your CSV by having each timestamp on rows, and the name of the annotation as a column as seen in the picture above. Whenever you want a new annotation you add a new column and it’s respective date row.

Add this file to your report as a new Data Source.

Blending

Now that you have your annotation data source added to your report, you need to Blend with your primary data source. To blend the two you need to have a join key, in our example this was “timestamp”, as also the primary datasource was having this key for time series data. You may need to adapt your annotation data source to match the format for the join key, it could be a date in different date format.

The process is the following:

In the report Dashboard below the data source for a chart find option to Blend data

Start the Blending wizard

Select from your data source the Annotation data source

Set the join keys , in our example: timestamp

, in our example: timestamp On the annotations data source: add all fields to the Metrics group

On the primary data source: add all fields if they are missing to the Metrics group

No need to add fields to other groups like Dimensions, Date range, Join Keys.

On the right you should have a live view of your blended data source, give it a name, and make sure you have all your primary source fields and the annotation fields you just added

In case a field shows up duplicate, find from which data source panel you need to remove

In the end you end up having a screen like: