Grouped Column Chart With Missing Values

Sometimes the chart data is not always complete. These holes in the data can wreck havoc on the visual correctness of your charts. Moreover, many of d3's internals assume the data will be sanitized before being handed off. For this reason the parsers have a defined() method which tells d4 how to check the incoming data. D4's defined() method is meant to follow the approach of d3's native method of the same name. Any data that returns false will not be included in the dataset sent to d3. The following example demonstrates this process.

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