Hi, and welcome back to the BStreams blog! We have some super exciting news to share with you: starting today, you can link two or more charts through a master-slave relationship thanks to the drill-through-chart brand new advanced feature.
Using this option, you will be able to drill into more specific charts, having a more detailed level of data analysis.
Drill-through-chart: what is and when to use it
The drill-through-chart feature enables users to connect two or more charts and synchronize data through a master-slave relationship. In essence, as the term suggests, it is a hierarchical relationship composed of the following charts:
Master chart: it is the main chart in hierarchical order, where the filter panel can be applied, and other charts are connected. That means the chart on which filters can be applied and which other charts are linked. When a filter is applied to a master chart, the filtered values will be automatically propagated to the slave charts with the only elements of the key field present in the dataset of the first chart.
Slave chart: the remaining charts are called slaves because they are directly connected to the master chart through a key field. No filter panel can be applied on these charts.
The master and the slave chart have the same or two different datasets with a key field in common: the master dataset is the dataset associated with the master chart, while the slave dataset is related to the slave chart.
This feature is especially useful with vast datasets because it allows users to move from a general to a more detailed chart. In general, every time you need a more specific level of analysis, consider using this feature.
How to apply a drill-chart on BStreams
1.Open a new project: be sure you already have at least two charts on your Bstreams, and their datasets share a common key field. The name of the key doesn’t matter; it can be different on both datasets.
2. Connect chart: afterward, scroll down the data panel and click on the Connect chart button. Select the slave chart to connect to the master, and choose two dimensions to create the connection. After the connection has been established, the slave chart will be filtered for only the values of the key field available on the master chart.
Repeat the same operation if you have more than two graphs.
3. Apply a dataset filter: to make the relationship between the charts interactive, apply a dataset filter on the master chart. Dataset filters allow users to select specific values from each available field in the original dataset, ensuring maximum analysis freedom.
Click View on the top right to see the result.
A real example of a drill-through-chart
The following examples are based on real datasets from our Data Hub: Covid-19 Italian regions. Every DataHub dataset will be automatically updated every time new data are available. This way,
In the first example, we have created two charts: the first one represents the total new positives cases for the Italian regions while the second one shows the trend.
The columns chart is connected with the line chart by the field codice_regione.
Now we can open up the View editor and try to make some selections using the filter panel.
For example, we can filter for Lombardia (under denominazione_regione) and analyze its trend on the line chart.
So far, so good, but what if we wanted to add a second filter to focus on a specific range of days?
There’s no answer to this question, and that’s because the values of the key field – codice_regione – don’t change if we select any date.
We can apply a subtle trick to reach our goal: we can include the date field into the key.
In the dataset panel, we edit the dataset and add one more calculated field: data & “|” & codice_regione (the “|” is not strictly necessary but can help if we wanted to split the field further). After that, we change the key field in the master-slave relationship using our new calculated field. Now, we can filter for Lombardia and then for any set of dates.
Well, that’s it for now! This was an explanation of how our new feature works. Wanna try this advanced feature or your next chart? Join us at www.bstreams.io
If you still have doubts or questions, feel free to get in touch with us at firstname.lastname@example.org