Tag: pivot

Pivot C# Array or DataTable: Convert a Column To a Row with LINQ

My Previous post explains how to convert a column to row in JavaScript array. In this post, we will do the same thing but with C# Array and DataTable using the power of LINQ or Lambda expression. For simplicity, I am using the same data.

C# Array To Pivot DataTable:

Here is the C# array object:

var data = new[] { 
              new { Product = "Product 1", Year = 2009, Sales = 1212 },
              new { Product = "Product 2", Year = 2009, Sales = 522 },
              new { Product = "Product 1", Year = 2010, Sales = 1337 },
              new { Product = "Product 2", Year = 2011, Sales = 711 },
              new { Product = "Product 2", Year = 2012, Sales = 2245 },
              new { Product = "Product 3", Year = 2012, Sales = 1000 }
          };

On Googling, I found the following generic method in StackOverflow thread.

public static DataTable ToPivotTable<T, TColumn, TRow, TData>(
    this IEnumerable<T> source,
    Func<T, TColumn> columnSelector,
    Expression<Func<T, TRow>> rowSelector,
    Func<IEnumerable<T>, TData> dataSelector)
        {
            DataTable table = new DataTable();
            var rowName = ((MemberExpression)rowSelector.Body).Member.Name;
            table.Columns.Add(new DataColumn(rowName));
            var columns = source.Select(columnSelector).Distinct();
 
            foreach (var column in columns)
                table.Columns.Add(new DataColumn(column.ToString()));
 
            var rows = source.GroupBy(rowSelector.Compile())
                             .Select(rowGroup => new
                             {
                                 Key = rowGroup.Key,
                                 Values = columns.GroupJoin(
                                     rowGroup,
                                     c => c,
                                     r => columnSelector(r),
                                     (c, columnGroup) => dataSelector(columnGroup))
                             });
 
            foreach (var row in rows)
            {
                var dataRow = table.NewRow();
                var items = row.Values.Cast<object>().ToList();
                items.Insert(0, row.Key);
                dataRow.ItemArray = items.ToArray();
                table.Rows.Add(dataRow);
            }
 
            return table;
        }

You can create a static class for extension methods and put it there.
To convert Year values to columns and get Pivot DataTable:

var pivotTable = data.ToPivotTable(
              item => item.Year, 
              item => item.Product,  
              items => items.Any() ? items.Sum(x=>x.Sales) : 0);

You will get the following output:

C# Array to Pivot Dynamic Array:

You might want to get the List<dynamic> or dynamic[] instead of getting DataTable after converting columns to rows. It is handy in ASP.NET Web API to return JSON response.

To do it, I updated the extension method to get the dynamic object. use following extension method:

public static dynamic[] ToPivotArray<T, TColumn, TRow, TData>(
this IEnumerable<T> source,
Func<T, TColumn> columnSelector,
Expression<Func<T, TRow>> rowSelector,
Func<IEnumerable<T>, TData> dataSelector)
       {
 
           var arr = new List<object>();
           var cols = new List<string>();
           String rowName = ((MemberExpression)rowSelector.Body).Member.Name;
           var columns = source.Select(columnSelector).Distinct();       
 
           cols =(new []{ rowName}).Concat(columns.Select(x=>x.ToString())).ToList();
 
 
           var rows = source.GroupBy(rowSelector.Compile())
                            .Select(rowGroup => new
                            {
                                Key = rowGroup.Key,
                                Values = columns.GroupJoin(
                                    rowGroup,
                                    c => c,
                                    r => columnSelector(r),
                                    (c, columnGroup) => dataSelector(columnGroup))
                            }).ToArray();
 
 
           foreach (var row in rows)
           {
               var items = row.Values.Cast<object>().ToList();
               items.Insert(0, row.Key);
               var obj = GetAnonymousObject(cols, items);
               arr.Add(obj);               
           }
           return arr.ToArray();
       }
 private static dynamic GetAnonymousObject(IEnumerable<string> columns, IEnumerable<object> values)
       {
           IDictionary<string, object> eo = new ExpandoObject() as IDictionary<string, object>;
           int i;
           for (i = 0; i < columns.Count(); i++)
           {
               eo.Add(columns.ElementAt<string>(i), values.ElementAt<object>(i));
           }
           return eo;
       }

ExpandoObject is used to create dynamic object.
Now, to convert row to column and get dynamic array:

var pivotArray = data.ToPivotArray(
                item => item.Year,
               item => item.Product,
               items => items.Any() ? items.Sum(x => x.Sales) : 0);

You can easily convert in JSON format

String json = JsonConvert.SerializeObject(pivotArray, new KeyValuePairConverter());

C# DataTable to Pivot DataTable:

Let us have a DataTable with same data:

DataTable myDataTable = new DataTable();
myDataTable.Columns.AddRange(new DataColumn[3] { new DataColumn("Product"), new DataColumn("Year", typeof(int)), new DataColumn("Sales", typeof(int)) });
myDataTable.Rows.Add("Product 1", 2009, 1212);
myDataTable.Rows.Add("Product 2", 2009, 522);
myDataTable.Rows.Add("Product 1", 2010, 1337);
myDataTable.Rows.Add("Product 2", 2011, 711);
myDataTable.Rows.Add("Product 2", 2012, 2245);
myDataTable.Rows.Add("Product 3", 2012, 1000);

You can use the same extension method to get Pivot DataTable like below.

var data2 = myDataTable.AsEnumerable().Select(x=> new { 
               Product =x.Field<String>("Product"), 
               Year= x.Field<int>("Year"), 
               Sales = x.Field<int>("Sales") });
           
           DataTable pivotDataTable =data2.ToPivotTable(
                item => item.Year,
               item => item.Product,
               items => items.Any() ? items.Sum(x => x.Sales) : 0);

Here is the result:

DataTable to List<dynamic>:

If you need to convert DataTable to List of dynamic object then use following extension method:

public static List<dynamic> ToDynamicList(this DataTable dt)
       {
           var list = new List<dynamic>();
           foreach (DataRow row in dt.Rows)
           {
               dynamic dyn = new ExpandoObject();
               list.Add(dyn);
               foreach (DataColumn column in dt.Columns)
               {
                   var dic = (IDictionary<string, object>)dyn;
                   dic[column.ColumnName] = row[column];
               }
           }
           return list;
       }

Here is the result:

Group by Multiple Columns

Here is a code to group data based on multiple columns.

testDt = GetTestDate();
        var data2 = testDt.Tables[0].AsEnumerable().Select(x => new
        {
            Family = x.Field<int>("tdFamily"),
            Class = x.Field<short>("luClass"),
            Region = x.Field<short>("luRegion"),
            Year = x.Field<int>("tdYear"),
            Population = x.Field<decimal>("tdPopulation ")
        });

        DataTable pivotDataTable = data2.ToPivotTable(
             item => item.Year,
            item => new{ item.Family, item.Class, item.Region},
            items => items.Any() ? items.Sum(x => x.Allocation) : 0
            );

         public static DataTable ToPivotTable<T, TColumn, TRow, TData>(
         this IEnumerable<T> source,
         Func<T, TColumn> columnSelector,
         Expression<Func<T, TRow>> rowSelector,
         Func<IEnumerable<T>, TData> dataSelector)
    {
        DataTable table = new DataTable();
        var rowsName = ((NewExpression)rowSelector.Body).Members.Select(s => s).ToList();
        foreach (var row in rowsName)
        {
            var name = row.Name; 
            table.Columns.Add(new DataColumn(name));
        }
        var columns = source.Select(columnSelector).Distinct();
        foreach (var column in columns)
            table.Columns.Add(new DataColumn(column.ToString()));
        var rows = source.GroupBy(rowSelector.Compile())
                         .Select(rowGroup => new
                         {
                             Key = rowGroup.Key,
                             Values = columns.GroupJoin(
                                 rowGroup,
                                 c => c,
                                 r => columnSelector(r),
                                 (c, columnGroup) => dataSelector(columnGroup))
                         });

        foreach (var row in rows)
        {
            var dataRow = table.NewRow();
            var items = row.Values.Cast<object>().ToList();
            string[] keyRow = row.Key.ToString().Split(',');
            int index = 0;
            foreach (var key in keyRow)
            {
                string keyValue = key.Replace("}", "").Split('=')[1].Trim();
                items.Insert(index, keyValue);
                index++;
            }
            dataRow.ItemArray = items.ToArray();
            table.Rows.Add(dataRow);
        }
        return table;
    }

Conclusion:

In this post, we played with C# Array, DataTable and implemented to convert row to column and get Pivot Array, DataTable and List of dynamic object.

Pivot a JavaScript Array: Convert a Column to a Row

Sometimes we need to convert a column to row in JavaScript array. It might be helpful to pass it as web service argument, generating chart dynamically or to display data in more meaningful way. In this post, we will create a method which converts a specified column to row in JavaScript array like below:

Consider the following array;

var arr = [
//["Product", "Year", "Sales"],
["Product 1", "2009", "1212"],
["Product 2", "2009", "522"],
["Product 1", "2010", "1337"],
["Product 2", "2011", "711"],
["Product 2", "2012", "2245"],
["Product 3", "2012", "1000"]
];

Use following method to convert this array;

function getPivotArray(dataArray, rowIndex, colIndex, dataIndex) {
        //Code from https://techbrij.com
        var result = {}, ret = [];
        var newCols = [];
        for (var i = 0; i < dataArray.length; i++) {
 
            if (!result[dataArray[i][rowIndex]]) {
                result[dataArray[i][rowIndex]] = {};
            }
            result[dataArray[i][rowIndex]][dataArray[i][colIndex]] = dataArray[i][dataIndex];
 
            //To get column names
            if (newCols.indexOf(dataArray[i][colIndex]) == -1) {
                newCols.push(dataArray[i][colIndex]);
            }
        }
 
        newCols.sort();
        var item = [];
 
        //Add Header Row
        item.push('Item');
        item.push.apply(item, newCols);
        ret.push(item);
 
        //Add content 
        for (var key in result) {
            item = [];
            item.push(key);
            for (var i = 0; i < newCols.length; i++) {
                item.push(result[key][newCols[i]] || "-");
            }
            ret.push(item);
        }
        return ret;
    }

In above method:
dataArray: Array to be converted
rowIndex: Index of column in array which is to be kept as first column
colIndex: Index of column whose values to be converted as columns in the output array.
dataIndex: Index of column whose values to be used as data (displayed in tabular/grid format).

The logic of method is simple. First it iterates the given array and create a result object of [rowIndex],[colIndex] = [dataIndex] format so that it can be fetched easily by using associative array like syntax. In the same iteration, we put unique values of colIndex in newCols array which will be used to create new columns. After this loop, we will get result object and newCols array. Now create a return array (ret), push newCols values for Header data and iterate result object, push values in ret object. Finally, ret variable will have the converted array.

Use this function to show HTML table;

function arrayToHTMLTable(myArray) {
           var result = "<table border='1' cellpadding='7' cellspacing='0'>";
           for (var i = 0; i < myArray.length; i++) {
               result += "<tr>";
               for (var j = 0; j < myArray[i].length; j++) {
                   result += "<td>" + myArray[i][j] + "</td>";
               }
               result += "</tr>";
           }
           result += "</table>";
 
           return result;
       }

Add following on HTML side;

<h2>Original Array</h2>
   <div id="orgTable"></div>
 
   <h2>Converted Array</h2>
   <div id="pivotTable"></div>

jQuery to show the results;

$(function () {
          var output = getPivotArray(arr, 0, 1, 2);
          $('#orgTable').html(arrayToHTMLTable(arr));
          $('#pivotTable').html(arrayToHTMLTable(output));
      });

Reference

https://www.cnblogs.com/vvull/p/14744863.html

https://medium.com/@saravanan16498/pivot-and-group-data-sk-yazhini9798-4a63e5cc3dd3