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Exception on ReadFromEnumerable with NULL values data #2489

jwood803 opened this Issue Feb 10, 2019 · 1 comment


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jwood803 commented Feb 10, 2019

System information

  • OS version/distro:
    OS Name: Windows
    OS Version: 10.0.17134
    OS Platform: Windows
    RID: win10-x64
  • .NET Version (eg., dotnet --info):
    .NET Core SDK (reflecting any global.json):
    Version: 3.0.100-preview-009812


  • What did you do?
    Loaded the wine data into a database and read data to use in ReadFromEnumerable

  • What happened?
    Got the below exception when loading the data into ReadFromEnumerable. I believe this is because there are null values within the data.

     System.ArgumentOutOfRangeException: 'Could not determine an IDataView type for member 
     Parameter name: rawType'
  • What did you expect?

Source code / logs

Have this ML.NET code:

var dbData = ReadFromDatabase();

var context = new MLContext();

var mlData = context.Data.ReadFromEnumerable(dbData);

And a preview of dbData where I think it's failing at:

    "Type": "white",
    "FixedAcidity": null,
    "VolatileAcidity": 1.0,
    "CitricAcid": 0.0,
    "ResidualSugar": 1.0,
    "Chlorides": 0.0,
    "FreeSulfurDioxide": 29.0,
    "TotalSulfureDioxide": 75.0,
    "Density": 1.0,
    "Ph": 3.0,
    "Sulphates": 0.0,
    "Alcohol": 13.0,
    "Quality": 8.0

Also, is this the correct way to handle missing data when reading from a database instead of from a CSV file? Or should I be handling it another way?


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Ivanidzo4ka commented Feb 11, 2019

You are right, it's related to nullable class. This cryptic message comes from here:

else if (!itemType.TryGetDataKind(out _))

where we don't know how to map Nullable to internal type.

@TomFinley I think we discussed that long time ago, and decided what user should handle that case (Nullable<Type>) by themselves. Is it still the case?

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