RDataFrame data source class to interface with Apache Arrow.
The RArrowDS implements a proxy RDataSource to be able to use Apache Arrow tables with RDataFrame.
A RDataFrame that adapts an arrow::Table class can be constructed using the factory method ROOT::RDF::MakeArrowDataFrame, which accepts one parameter:
The types of the columns are derived from the types in the associated arrow::Schema.
Definition at line 22 of file RArrowDS.hxx.
Public Member Functions | |
RArrowDS (std::shared_ptr< arrow::Table > table, std::vector< std::string > const &columns) | |
Constructor to create an Arrow RDataSource for RDataFrame. More... | |
~RArrowDS () | |
Destructor. More... | |
const std::vector< std::string > & | GetColumnNames () const override |
Returns a reference to the collection of the dataset's column names. More... | |
std::vector< std::pair< ULong64_t, ULong64_t > > | GetEntryRanges () override |
Return ranges of entries to distribute to tasks. More... | |
std::string | GetLabel () override |
Return a string representation of the datasource type. More... | |
std::string | GetTypeName (std::string_view colName) const override |
Type of a column as a string, e.g. More... | |
bool | HasColumn (std::string_view colName) const override |
Checks if the dataset has a certain column. More... | |
void | Initialise () override |
Convenience method called before starting an event-loop. More... | |
void | InitSlot (unsigned int slot, ULong64_t firstEntry) override |
Convenience method called at the start of the data processing associated to a slot. More... | |
bool | SetEntry (unsigned int slot, ULong64_t entry) override |
Advance the "cursors" returned by GetColumnReaders to the selected entry for a particular slot. More... | |
void | SetNSlots (unsigned int nSlots) override |
Inform RDataSource of the number of processing slots (i.e. More... | |
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virtual | ~RDataSource ()=default |
virtual void | Finalise () |
Convenience method called after concluding an event-loop. More... | |
virtual void | FinaliseSlot (unsigned int) |
Convenience method called at the end of the data processing associated to a slot. More... | |
virtual const std::vector< std::string > & | GetColumnNames () const =0 |
Returns a reference to the collection of the dataset's column names. More... | |
template<typename T > | |
std::vector< T ** > | GetColumnReaders (std::string_view columnName) |
Called at most once per column by RDF. More... | |
virtual std::vector< std::pair< ULong64_t, ULong64_t > > | GetEntryRanges ()=0 |
Return ranges of entries to distribute to tasks. More... | |
virtual std::string | GetLabel () |
Return a string representation of the datasource type. More... | |
virtual std::string | GetTypeName (std::string_view) const =0 |
Type of a column as a string, e.g. More... | |
virtual bool | HasColumn (std::string_view) const =0 |
Checks if the dataset has a certain column. More... | |
virtual void | Initialise () |
Convenience method called before starting an event-loop. More... | |
virtual void | InitSlot (unsigned int, ULong64_t) |
Convenience method called at the start of the data processing associated to a slot. More... | |
virtual bool | SetEntry (unsigned int slot, ULong64_t entry)=0 |
Advance the "cursors" returned by GetColumnReaders to the selected entry for a particular slot. More... | |
virtual void | SetNSlots (unsigned int nSlots)=0 |
Inform RDataSource of the number of processing slots (i.e. More... | |
Private Member Functions | |
std::vector< void * > | GetColumnReadersImpl (std::string_view name, const std::type_info &type) override |
This needs to return a pointer to the pointer each value getter will point to. More... | |
Private Attributes | |
std::vector< std::string > | fColumnNames |
std::vector< std::pair< ULong64_t, ULong64_t > > | fEntryRanges |
std::vector< std::pair< size_t, size_t > > | fGetterIndex |
size_t | fNSlots = 0U |
std::shared_ptr< arrow::Table > | fTable |
std::vector< std::unique_ptr< ROOT::Internal::RDF::TValueGetter > > | fValueGetters |
Additional Inherited Members | |
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using | Record_t = std::vector< void * > |
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virtual std::string | AsString () |
virtual Record_t | GetColumnReadersImpl (std::string_view name, const std::type_info &)=0 |
type-erased vector of pointers to pointers to column values - one per slot More... | |
#include <ROOT/RArrowDS.hxx>
ROOT::RDF::RArrowDS::RArrowDS | ( | std::shared_ptr< arrow::Table > | inTable, |
std::vector< std::string > const & | inColumns | ||
) |
Constructor to create an Arrow RDataSource for RDataFrame.
[in] | table | the arrow Table to observe. |
[in] | columns | the name of the columns to use In case columns is empty, we use all the columns found in the table |
Definition at line 387 of file RArrowDS.cxx.
ROOT::RDF::RArrowDS::~RArrowDS | ( | ) |
Destructor.
Definition at line 459 of file RArrowDS.cxx.
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overridevirtual |
Returns a reference to the collection of the dataset's column names.
Implements ROOT::RDF::RDataSource.
Definition at line 463 of file RArrowDS.cxx.
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overrideprivatevirtual |
This needs to return a pointer to the pointer each value getter will point to.
Implements ROOT::RDF::RDataSource.
Definition at line 569 of file RArrowDS.cxx.
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overridevirtual |
Return ranges of entries to distribute to tasks.
They are required to be contiguous intervals with no entries skipped. Supposing a dataset with nEntries, the intervals must start at 0 and end at nEntries, e.g. [0-5],[5-10] for 10 entries. This function will be invoked repeatedly by RDataFrame as it needs additional entries to process. The same entry range should not be returned more than once. Returning an empty collection of ranges signals to RDataFrame that the processing can stop.
Implements ROOT::RDF::RDataSource.
Definition at line 468 of file RArrowDS.cxx.
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overridevirtual |
Return a string representation of the datasource type.
The returned string will be used by ROOT::RDF::SaveGraph() to represent the datasource in the visualization of the computation graph. Concrete datasources can override the default implementation.
Reimplemented from ROOT::RDF::RDataSource.
Definition at line 594 of file RArrowDS.cxx.
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overridevirtual |
Type of a column as a string, e.g.
GetTypeName("x") == "double"
. Required for jitting e.g. df.Filter("x>0")
.
[in] | columnName | The name of the column |
Implements ROOT::RDF::RDataSource.
Definition at line 474 of file RArrowDS.cxx.
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overridevirtual |
Checks if the dataset has a certain column.
[in] | columnName | The name of the column |
Implements ROOT::RDF::RDataSource.
Definition at line 492 of file RArrowDS.cxx.
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overridevirtual |
Convenience method called before starting an event-loop.
This method might be called multiple times over the lifetime of a RDataSource, since users can run multiple event-loops with the same RDataFrame. Ideally, Initialise
should set the state of the RDataSource so that multiple identical event-loops will produce identical results.
Reimplemented from ROOT::RDF::RDataSource.
Definition at line 588 of file RArrowDS.cxx.
Convenience method called at the start of the data processing associated to a slot.
[in] | slot | The data processing slot wihch needs to be initialised |
[in] | firstEntry | The first entry of the range that the task will process. This method might be called multiple times per thread per event-loop. |
Reimplemented from ROOT::RDF::RDataSource.
Definition at line 510 of file RArrowDS.cxx.
Advance the "cursors" returned by GetColumnReaders to the selected entry for a particular slot.
[in] | slot | The data processing slot that needs to be considered |
[in] | entry | The entry which needs to be pointed to by the reader pointers Slots are adopted to accommodate parallel data processing. Different workers will loop over different ranges and will be labelled by different "slot" values. Returns true if the entry has to be processed, false otherwise. |
Implements ROOT::RDF::RDataSource.
Definition at line 501 of file RArrowDS.cxx.
Inform RDataSource of the number of processing slots (i.e.
worker threads) used by the associated RDataFrame. Slots numbers are used to simplify parallel execution: RDataFrame guarantees that different threads will always pass different slot values when calling methods concurrently.
Implements ROOT::RDF::RDataSource.
Definition at line 553 of file RArrowDS.cxx.
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private |
Definition at line 26 of file RArrowDS.hxx.
Definition at line 25 of file RArrowDS.hxx.
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private |
Definition at line 29 of file RArrowDS.hxx.
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private |
Definition at line 27 of file RArrowDS.hxx.
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private |
Definition at line 24 of file RArrowDS.hxx.
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private |
Definition at line 30 of file RArrowDS.hxx.