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DataFrame merge results in column datatype problem #6127
Description
.Net Core 3.1
Microsoft.Data.Analysis Nuget package version: 0.19.1
The last line of the following program crashes with the exception:
System.ArgumentException: 'Cannot cast column holding System.Double values to type System.Double'
using Microsoft.Data.Analysis;
using System;
using System.Linq;
namespace TestDataFRame
{
internal class Program
{
static void Main(string[] args)
{
DateTime?[] dates1 = { new DateTime(2022, 03, 01), new DateTime(2022, 03, 02), new DateTime(2022, 03, 03) };
double?[] closePrices = { 10.5, 12.4, 11.3 };
DateTime?[] dates2 = { new DateTime(2022, 03, 01), new DateTime(2022, 03, 02), new DateTime(2022, 03, 03) };
double[] shortPercentages = { 2.34, 2.36, 3.01 };
DataFrame dataFrame1 = new DataFrame();
dataFrame1.Columns.Add(new PrimitiveDataFrameColumn<DateTime>("Date", dates1));
dataFrame1.Columns.Add(new DoubleDataFrameColumn("ClosePrice", closePrices));
var numbers1 = dataFrame1.Columns.GetDoubleColumn("ClosePrice").ToArray();
DataFrame dataFrame2 = new DataFrame();
dataFrame2.Columns.Add(new PrimitiveDataFrameColumn<DateTime>("Date", dates1));
dataFrame2.Columns.Add(new DoubleDataFrameColumn("ShortPercentage", shortPercentages));
var numbers2 = dataFrame2.Columns.GetDoubleColumn("ShortPercentage").ToArray();
DataFrame dataFrame = dataFrame1.Merge<DateTime>(dataFrame2, "Date", "Date", joinAlgorithm: JoinAlgorithm.Left);
var numbers = dataFrame.Columns.GetDoubleColumn("ClosePrice").ToArray();
}
}
}
Activity
michaelgsharp commentedon Mar 18, 2022
Alright, the issue is that merge is calling "Clone" on the columns, but Clone returns slightly different types. For example, Instead of returning
DoubleDataFrameColumnit is returningPrimitiveDataFrameColumn<double>.DoubleDataFrameColumndoes extendPrimitiveDataFrameColumn<double>but they aren't the same type obviously. The problem then is that in the call toGetDoubleColumn, the checkif (column is DoubleDataFrameColumn ret)fails because its not actually aDoubleDataFrameColumnanymore.I not sure the exact best way to fix this from a code standpoint. Probably needs a little bit more investigation to figure out the best way. @luisquintanilla for visiblity.