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Summarize Rounding Error

DavidxL
9 - Comet

I have a dataset with large numbers (float) on which I need to calculate averages by group. Floats are not recommended for Summarize/Group Bys, so what data type do I need to convert to in order to preserve accuracy?

 

In the attached workflow, see group value "0.007916" which has values B = 1095091000 and 1074619000. These are converted into 1095091072 and 1074619392 when using FixedDecimal type.

4 REPLIES 4
MarqueeCrew
20 - Arcturus
20 - Arcturus

I'd use DOUBLE.

 

Cheers,

Mark

Alteryx ACE & Top Community Contributor

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DavidxL
9 - Comet

Using the Select tool to convert to Double results in the numbers changing. Is there a different method of converting?

 

The highlighted numbers in column B should end in zero.

 

double.PNG

SeanAdams
17 - Castor
17 - Castor

easiest way is to use a formula - it gives you far more control over changing types, and there are loads of type conversion functions available (using select, you have no control over how it's converted)

 

 

2017-08-08_9-19-58.png

 

2017-08-08_9-20-12.png

DavidxL
9 - Comet

I found that an earlier data import step had automatically loaded/defined the numbers as floats, and so the numbers displayed by the Browse tool were only exact to 7 digits of precision despite showing more digits. It seems non-intuitive to me as I would expect some sort of indication that while "1074619000" is being displayed, the actual value is "1.074619E9" with no guarantee for the last 3 digits.

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