dotnet/machinelearning · error · ArgumentException

Strings.MismatchedColumnLengths

Error message

Strings.MismatchedColumnLengths

What it means

Binary arithmetic between two DecimalDataFrameColumn operands requires both columns to have the same number of rows, since the operation is applied element-wise. When the operand column's Length differs from this column's Length, HandleOperationImplementation throws ArgumentException with paramName `column` and message Strings.MismatchedColumnLengths.

Source

Thrown at src/Microsoft.Data.Analysis/PrimitiveDataFrameColumn.BinaryOperationImplementations.Exploded.cs:22

// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

// Generated from DataFrameColumn.BinaryOperationImplementations.ExplodedColumns.tt. Do not modify directly

using System;
using System.Collections.Generic;

namespace Microsoft.Data.Analysis
{

    public partial class DecimalDataFrameColumn
    {
        //Binary Operations
        internal DecimalDataFrameColumn HandleOperationImplementation(BinaryOperation operation, DecimalDataFrameColumn column, bool inPlace = false)
        {
            if (column.Length != Length)
            {
                throw new ArgumentException(Strings.MismatchedColumnLengths, nameof(column));
            }
            var newColumn = inPlace ? this : (DecimalDataFrameColumn)Clone();
            newColumn.ColumnContainer.HandleOperation(operation, column.ColumnContainer);
            return newColumn;
        }

        //Binary Scalar Operations
        internal DecimalDataFrameColumn HandleOperationImplementation(BinaryOperation operation, decimal right, bool inPlace = false)
        {
            var newColumn = inPlace ? this : (DecimalDataFrameColumn)Clone();
            newColumn.ColumnContainer.HandleOperation(operation, right);
            return newColumn;
        }

        internal DecimalDataFrameColumn HandleReverseOperationImplementation(BinaryOperation operation, decimal right, bool inPlace = false)
        {
            var newColumn = inPlace ? this : (DecimalDataFrameColumn)Clone();
            newColumn.ColumnContainer.HandleReverseOperation(operation, right);

View on GitHub (pinned to 7b76e69cf9)

Solutions

1. Before the operation, verify column.Length == thisColumn.Length; if not, align the data (filter, slice, or join) so both have the same rows.
2. Ensure both columns come from the same DataFrame or were derived with the same row selection.
3. For scalar/element-wise math on mismatched columns, first truncate the longer column to the shorter length via slicing/cloning.

Example fix

// before
var result = price * qty; // price.Length == 100, qty.Length == 90
// after
if (price.Length != qty.Length)
    throw new InvalidOperationException("Align columns before arithmetic");
var result = price * qty;

if (left.Length != right.Length) throw new InvalidOperationException($"Column length mismatch: {left.Length} vs {right.Length}");

static bool SameLength(DecimalDataFrameColumn a, DecimalDataFrameColumn b) => a.Length == b.Length;

try { var result = left * right; }
catch (ArgumentException ex) when (ex.Message == Strings.MismatchedColumnLengths || ex.ParamName == "column")
{
    // align/slice columns and retry
}

When it happens

Trigger: Calling Add/Subtract/Multiply/Divide/Modulo (or the +,-,*,/,% operators) on two DecimalDataFrameColumn instances of different Length, optionally with inPlace: true.

Common situations: Arithmetic between columns from different DataFrames with different row counts, after filtering one DataFrame but not the other, or mixing a full column with a sliced column.

Related errors

• The method or operation is not implemented.
• Strings.MismatchedColumnLengths
• string.Format(Strings.MismatchedValueType, typeof(string))
• String.Format(Strings.MultipleMismatchedValueType, typeof(lo
• Strings.MapIndicesExceedsColumnLength

AI-assisted analysis of dotnet/machinelearning@7b76e69cf9 (2026-09-11). Data as JSON: /api/errors/f7a28a965485751d. Report an issue: GitHub.