Chapter 6 world_countries.csv: issues with Altair and column names which include periods #54
Description
There is apparently an issue in Vega which makes it so that Altair cannot display data pulled from columns which have a period in their name --- the world_countries.csv file in chapter 6 of httlads has a column called 'Pop. Density'. If one tries to use Altair to display a chart with data from that column, it will not be able to display it properly. For example, it occurs when one creates a scatterplot of 'Pop. Density' with 'GDP'.
There is a workaround by calling the column in Altair with 'Pop. Density' rather than 'Pop. Density'. However, this seems idiosyncratic enough that it would be better to rename the column in world_countries.csv to Pop Density in order to avoid this issue.