Case insensitive group on multiple columns in C#

Case insensitive group on multiple columns in C#

You can perform a case-insensitive group on multiple columns in C# by using the GroupBy method with a custom IEqualityComparer. Here's an example code that demonstrates how to do this:

using System; using System.Collections.Generic; using System.Linq; // Define a custom comparer that performs a case-insensitive comparison of two strings public class CaseInsensitiveStringComparer : IEqualityComparer<string> { public bool Equals(string x, string y) { return String.Equals(x, y, StringComparison.OrdinalIgnoreCase); } public int GetHashCode(string obj) { return obj.ToLower().GetHashCode(); } } // Example usage var data = new List<string[]>() { new string[] { "John", "Doe", "jdoe@example.com" }, new string[] { "jane", "smith", "jsmith@example.com" }, new string[] { "Jane", "Smith", "jane.smith@example.com" }, new string[] { "Joe", "Bloggs", "jbloggs@example.com" } }; var groups = data.GroupBy(row => new { First = row[0], Last = row[1] }, new CaseInsensitiveStringComparer()); foreach (var group in groups) { Console.WriteLine($"{group.Key.First} {group.Key.Last} ({group.Count()}):"); foreach (var row in group) { Console.WriteLine($" {row[2]}"); } }

In this example, the data variable is a list of string arrays that represents a table with three columns: first name, last name, and email address. The GroupBy method is used to group the data by the first name and last name columns, while ignoring case in the comparison. To do this, a custom IEqualityComparer is defined that performs a case-insensitive comparison of two strings. The Equals method uses the StringComparison.OrdinalIgnoreCase parameter to perform a case-insensitive comparison of the strings, and the GetHashCode method converts the string to lowercase before getting its hash code.

The GroupBy method is called with a lambda expression that returns an anonymous object with two properties: First and Last. This object is used as the key for grouping the data, and the custom CaseInsensitiveStringComparer is used to compare the keys.

Finally, the resulting groups are printed to the console. The Key property of each group is an anonymous object with the First and Last properties, and the Count method is used to get the number of rows in each group.

Examples

  1. "C# LINQ case-insensitive group by multiple columns"

    • Code:
      var groupedData = data.GroupBy(row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, StringComparer.OrdinalIgnoreCase);
    • Description: Uses LINQ to perform a case-insensitive group by on multiple columns in a collection.

  2. "C# LINQ case-insensitive group by multiple columns with projection"

    • Code:
      var groupedData = data.GroupBy( row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, (key, rows) => new { Key = key, Rows = rows.ToList() }, StringComparer.OrdinalIgnoreCase);
    • Description: Extends the previous example by projecting the grouped data into a custom result type.

  3. "C# LINQ case-insensitive group by dynamic columns"

    • Code:
      var columnsToGroupBy = new List<string> { "Column1", "Column2" }; var groupedData = data.GroupByDynamic(columnsToGroupBy, StringComparer.OrdinalIgnoreCase);
    • Description: Implements a method to dynamically specify columns for case-insensitive grouping using LINQ.

  4. "C# LINQ case-insensitive group by multiple columns with aggregation"

    • Code:
      var groupedData = data.GroupBy( row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, (key, rows) => new { Key = key, Count = rows.Count() }, StringComparer.OrdinalIgnoreCase);
    • Description: Extends the grouping to include an aggregation function, such as counting the number of items in each group.

  5. "C# LINQ case-insensitive group by multiple columns and sum"

    • Code:
      var groupedData = data.GroupBy( row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, (key, rows) => new { Key = key, Sum = rows.Sum(row => row.NumericColumn) }, StringComparer.OrdinalIgnoreCase);
    • Description: Illustrates a case-insensitive group by with multiple columns and a sum aggregation.

  6. "C# LINQ case-insensitive group by with custom equality comparer"

    • Code:
      var groupedData = data.GroupBy(row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, new CaseInsensitiveEqualityComparer());
    • Description: Utilizes a custom equality comparer for case-insensitive grouping with LINQ.

  7. "C# LINQ case-insensitive group by with complex object"

    • Code:
      var groupedData = data.GroupBy( row => new CustomObject { Property1 = row.Column1.ToLower(), Property2 = row.Column2.ToLower() }, StringComparer.OrdinalIgnoreCase);
    • Description: Demonstrates grouping by a custom object with case-insensitive comparison.

  8. "C# LINQ case-insensitive group by multiple columns and ordering"

    • Code:
      var groupedData = data.GroupBy( row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, StringComparer.OrdinalIgnoreCase) .OrderBy(group => group.Key.Column1) .ThenBy(group => group.Key.Column2);
    • Description: Adds sorting to the case-insensitive group by result based on multiple columns.

  9. "C# LINQ case-insensitive group by multiple columns and filtering"

    • Code:
      var groupedData = data .Where(row => !string.IsNullOrWhiteSpace(row.Column1) && !string.IsNullOrWhiteSpace(row.Column2)) .GroupBy(row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, StringComparer.OrdinalIgnoreCase);
    • Description: Filters out rows with empty or null values in the specified columns before performing case-insensitive grouping.

  10. "C# LINQ case-insensitive group by multiple columns and selecting specific fields"

    • Code:
      var groupedData = data .GroupBy( row => new { Column1 = row.Column1.ToLower(), Column2 = row.Column2.ToLower() }, (key, rows) => new { Key = key, Total = rows.Sum(row => row.NumericColumn) }, StringComparer.OrdinalIgnoreCase);
    • Description: Selects specific fields from the grouped data, demonstrating the flexibility of LINQ's group by operation.

More Tags

mat-file android-jetpack-navigation stock stub trigger.io mbunit meanjs amazon-s3 conflict intervals

More C# Questions

More Livestock Calculators

More Electronics Circuits Calculators

More Bio laboratory Calculators

More Auto Calculators