[yt-users] Erroneous values from 'TotalQuantity' derived quantity

[Anthony Harness]

I am trying to use the derived quantity, 'TotalQuantity', to count the
number of cells included in my cut_region as follows:

cut = dd.cut_region(["grid['x'] > 0.5"])
      #Example cut
numberCells = cut.quantities['TotalQuantity']('Ones')[0]
#Totals a 'one' for each cell, which gives the total number of cells being
used

This works fine when I have plenty of cells to split up between 84
processors (or when there are exactly zero cells in the cut), but when there
is a small number of cells in the cut (<~300), I get erroneous (way too
large) random values like 1.e18 or -4.2e17. I know there are cells in the
cut because I don't get a 'nan' when I calculate a 'WeightedAverageQuantity'
value. I have tried to use "cut['Density'].size" to get the number of cells,
but I get killed by the OOM Killer. My original data set has 1024^3 cells
and I am running on Kraken with 84 processors.

Thanks,
Anthony
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