OLAP library Release Notes PivotData Documentation

Version 1.4.2 (latest) 2023 Feb 02

PivotTable now skips Key.Empty keys when calculates ColumnKeys/RowKeys (github issue #11)

Version 1.4.1 2022 Jun 13

AverageAggregator (and SumAggregator) now returns null instead of zero if count=0 (like SQL AVG/SUM), issue #9

Version 1.4.0 2022 Jun 13

Added netstandard2.1 build
Added PivotData.ProcessDataAsync methods (available only in netstandard2.1 build)

Version 1.3.8 2020 May 27

NReco.PivotData goes open source: https://github.com/nreco/pivotdata
PivotTable class: fixed issue with sort-by-value for single-measure that is FormulaAggregator, fixed issue with sort-by-value when aggregator value is IList (ListAggregator, ListUniqueAggregator), added ability to set custom IComparer for values (ValuesComparer property)
PivotData class: fixed issue in ValueKey comparison for numeric dimension keys (cases like int vs long)

Version 1.3.7 2018 Jul 18

fixed PivotDataState serialization issue with Key.Empty
PivotData class: XOR-based hash function for keys replaced with sum-based to avoid collisions
performance optimization: less array allocations in PivotData.ProcessData method and PivotTable class

Version 1.3.6 2018 Apr 06

Version 1.3.5 2018 Feb 26

added QuantileAggregator to calculate specified quantile (median).
added PivotData.LazyAdd property (affects behaviour when non-existing key is accessed) - added netstandard2.0 build
efficient sub-totals calculation in PivotTable class (especially for large pivot tables)
now PivotData class correctly loads PivotDataState which has duplicate key entries

Version 1.3.4 2017 Feb 01

added SliceQuery.Measure overload that gives keys context for measure value calculation. Useful in cases when formula result depends on the key (for example, calculate yearly growth).
added PivotData.ProcessData overload that can accept another IPivotData instance as input. Useful for multi-stage calculation when one pivot table is calculated by results of another one.

Version 1.3.3 2016 Oct 18

added FormulaAggregator (based on CompositeAggregator) for on-the-fly formula calculations
added SliceQuery.Measure overload for defining formula-based measure
minor fix in MaxAggregator/MinAggregator Merge method (extra check for null)

Version 1.3.2 2016 Aug 14

improved performance for SliceQuery.Where(string,object[])
now PivotDataState Serialize/Deserialize methods are available in netstandard1.5 build
ListAggregator/ListAggregatorFactory can accept field name to collect field values instead of source objects
now MinAggregator/MaxAggregator may be used with any IComparable values, not only with numeric types

Version 1.3.1 2016 Jul 05

Fixed issue with incorrect grand-total non-lazy calculation for PivotData cube with exactly one dimension
Improved internal performance for PivotData lazy totals calculation (1.5x)
Drastically increased performance for PivotTable row/column totals calculation (10x+)
Added build for .NET Standards 1.5 (now PivotData can be used from .NET Core 1.0 apps)

Version 1.3.0 2016 May 10

Bugfix: PivotTable.PreserveGroupOrder works incorrectly for the last column/row.
Added ListAggregatorFactory (ListAggregator) for accumulating all values from an input source (works like LINQ GroupBy).
Added VarianceAggregatorFactory (VarianceAggregator) for calculating variance, standard deviation (stdev), sample variance and sample standard deviation.
Added ObjectMember that simplifies processing of custom data models (typed collections).
Added PivotDataHelper that provides utility methods for any IPivotData object: GetDimensionKeys and GetDimensionType.
Improved ConvertHelper.ConvertToDecimal method (now it supports all primitive number types) and added ConvertHelper.ConvertToDouble method.

Version 1.2.6 2016 Feb 04

introduced IPivotTable interface for alternative implementations/wrappers.
Added PivotTable.GetValue(ValueKey row, ValueKey col) method for key-based access to pivot table values; this signature can be used for getting sub-total values.
Added PivotTable.SortColumnKeysByRowKey and PivotTable.SortRowKeysByColumnKey methods for key-based sorting (useful for ordering by sub-total values).

Version 1.2.5 2016 Jan 13

Fixed PivotTable issue when the same dimension is used for both rows and columns (should be diagonal matrix result).
New IAggregator.AsComposite() extension method avoids boilerplate code (cast to CompositeAggregator) for accessing PivotData or PivotTable with several measures.
Added QueryCube example that illustrates how to use SliceQuery to filter/slice/dice, define derived (calculated) dimensions and measures.

Version 1.2.4 2015 Dec 11

Added PivotTable.PreserveGroupOrder option: when enabled sort by value reorders rows/columns only inside groups.
now PivotData works in lazy totals mode by default (this is backward-compatible change)
added SortAsComparer for defining explicit order of pivot table rows or columns
fixed NaturalSortKeyComparer (exception when dimension contains mixed types). In this case it fallbacks to comparison of string equivalents.
added NaturalSortKeyComparer.ReverseInstance

Version 1.2.3 2015 Sep 30

moved SliceQuery from extensions (PivotData Toolkit) to NReco.PivotData assembly. SliceQuery can be used for querying data cube in linq-style.
PivotTable class: added PivotData property for accessing underlying data cube, added SortRowKeys/SortColumnKeys overloads for specifying measure index (for pivot tables with several measures)
Overloaded ToString in IAggregatorFactory implementations (used for getting human-readable measure names)
now NReco.PivotData.dll is a signed (strongly named) assembly

Version 1.2.2 2015 July 27

added PivotData.CopyTo for custom merge/slice cube operations
added PivotTableMD class for creating n-dimensional (n>2) pivot table views
added overloads for PivotData/PivotTable that accept custom comparers of dimension keys
changed LazyTotals mode behaviour: now accessing grand-total value doesn't force calculation of all sub-totals (reason out-of-memory exception for large cubes)
a lot of other minor changes/fixes
introduced IPivotData interface
improved PivotData performance and decreased memory consumption

Version 1.2.0 2015 May 26

fixed issue with PivotData.Merge behavior (totals)
fixed issue with PivotData.ProcessData in lazy totals mode
added fast Serialize/Deserialize methods for PivotDataState
added Slice method for PivotData (reduce dimensions / filter data)
significantly improved performance and decreased memory consumption (Key class is no longer used for wrapping key objects)
added CsvDemo example (aggregates data from csv file)

Version 1.1.0 2015 Apr 10

dimension keys are sorted by default
added lazy totals calculation mode
added CompositeAggregator (enables ability to use several aggregators at once)
now PivotData dimensions are determined by single key
added PivotTable 2D view (slice) for PivotData. Supports: several dimensions for table rows/columns, sort row/columns by table values.

Version 1.0.1 2015 Mar 09

Version 1.0.0 2015 Feb 11

Initial PivotData library release. Implemented core features:

optimized totals calculation in batch processing model
merge operation for map/reduce usage scenario (parallel/distributed cube calculation)
basic set of aggregators: avg, count, count uniq / list uniq