Graph Builder: Heatmap Label By Value - How do I control the number of decimal points?

[#1]

In Graph Builder I am using a heat map to show the average gain for different combinations of wafers. I have set Label By Value, to get the mean gain value added to the plot for each combination, but I see no way to limit the number of decimal points in the calculated value (changing the number of decimal places for the :Gain column does not affect the label). If possible, I would also like to be able to make the labels bold, but I might be able to work that out through a temporary change to the Font settings.

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[#2]

Possible workaround: create a column with the means (rounded as desired) and use these values as labels. In Graph Builder, use Label by Row.

Current Data Table() << New Column("heatmap means",
    Numeric,
    "Continuous",
    Formula(Round(Col Mean(:Gain, :U1_LOTID, :U2_LOTID), 1)),
    <<label
);

[#3]

Thanks