TIBCO Spotfire

I am trying to calculate a weighted average of a certain parameter, say a material (M) weighted by cost (C).  I have used either the "WeightedAverage" function in spotfire and a custom equation to calculated the weighted average.  The result of this expression should be a single value.  However, when I try to put it on a bar chart or some other visualization, it requires me to provide an aggregation method as if there are multiple values present.

 Can someone provide some insight into why Spotfire is doing this?

 Thanks,

 Joel

Have you tried wrapping it into an avg() ? If it is only one value, it should not change it.

Christof

I have a similar issue. I put in the weightedaveragefunction with the two values and it gives me the same value on every line in the data set.

Here is a simple example of fake numbers showing the issue. When I I place the weightedAvg number in the bar chart I of course get bars of equal length no matter how I divide up the data.

Row     Value1 Value2 weightedAvg
Row 1  7.2          8          53.3
Row 2  6.3          9          53.3

If you want a unique value for groups in a calculated column, you need to use the over statement to provide the scope of the weighted average (i.e. county level, state, country, etc.)  Example as follows:

WeightedAverage([Weight_Column],[Value_Column]) over ([County])

If you only need to visualize the answer, and not use it in another calculation, you should be able to do it in a bar chart, and then choose rowid as your x-axis selector to expand the weighted average to the entire data set (or choose a grouped column to set a different scope)

Hope that helps!

Thanks,
Ryan