Vega-lite: Area chart with column facet channel has undefined subchart when there is partial data

[rmales]

Hi,

I'm trying to create an area chart with multiple subcharts using the column facet channel. But, I have found that if there is data missing, for any year on the x axis in my case, this seems to cause an subchart titled 'undefined' to be created. I guess I may be able to fix this by imputing the missing data. I'm opening this issue because the undefined subchart was unexpected to me, and seems at least undesirable if not a bug.

Example: https://vega.github.io/editor/#/url/vega-lite/N4KABGBEAkDODGALApgWwIaQFxUQFzwAdYsB6UgN2QHN0A6agSz0QFcAjOxge1IRQyUa6ALQAbZskoBmOgCtY3AHaQANOCgATdHkw5QECJAroxrZLGxgA2hsNgD9w5DxWAjAE4PAVnVPn8FaQAIIAqgDKanZOkIRBALIAmpF+-lAmZsjuAEweACx5Hm50Rd5uAAwAbJWp-rGBOOUlXl5u0oXeAOzVbp3REAC+tYaOda44nh41-QFBYSkzRnE4kEkLaemm5u7S2W6V0sWVhQAcPgXD9vVWTS3ee5V7h-nlbjNDM6Mx42CTnZezFbzKIbWIJZIgtLGLZZCbldpuXp0E6VTq9crlf6LKCEBpgW4tDwnXr3bxTIrvAFfK4-Sa+bGQPGQADCAAkAHKQurLKBrLkxDLbOGI7LZSp0UV5co+TrZAFLPFvfwffzU5y0rzTUFMtmc+U48HrKGC2G-V7SMp5Eq7To+aQefXXCaUz4MjUeLHaoK6-lXHmrCGOk3uTEI8VEvLZcp5e6O3HuF2qt3uTWOpnAuNBAAqAGkADK+5zBnAHbJ0bx5aRxvFNDHRzonaQNyoncpkk73E6Jpxqozu+leoERQtLIIABWZeoZxd+xU8J2rNzodYxKO80ey0mkjYbZWy3fsvag7s9UPTw8zKwAagBxABCI82mXcyJOp+5NeXK7cJ2yeU6UrSNKorrvuyrRAAuhoKpQMgSjwNwmiMEo1BWF8jLcGYqAqPoMyQAAZowyBiJoQSBACLgAJ6EKakBKNwqDIaYkDRDBRiUWheGEcRpErPGFF4NRtEAI6sOgSh4MwOiMFQLH2GxUAAB6cXU3EkUErgCUJQTcAATkhSjMaxwwYWIekqTEam8QaWk0UE9GMYZYiFpAYg0HB1lKKwYhiKx0GpJAGC6QA1kE6C6cgmAgAMQA

Thanks,
Richard

[kanitw]

Thanks for reporting!

It seems like the problem is due to the automatic impute logic that we have for stacked chart (This example has color).

The generated Vega impute transform should include p in the "groupby" ("groupby": ["p", "c"]). So this is definitely a bug.

[kanitw]

@domoritz -- not sure where the groupby gets added for AggregateNode, but I guess the same logic should be applied to fix this issue?

[kanitw]

NVM -- found the solution -- will be fixed in #4447