lsst::afw::table::SchemaMapper Class Reference

A mapping between the keys of two Schemas, used to copy data between them. More...

#include <SchemaMapper.h>

Public Member Functions
Schema const	getInputSchema () const
	Return the input schema (copy-on-write). More...
Schema const	getOutputSchema () const
	Return the output schema (copy-on-write). More...
Schema &	editOutputSchema ()
	Return a reference to the output schema that allows it to be modified in place. More...
template<typename T >
Key< T >	addOutputField (Field< T > const &newField, bool doReplace=false)
	Add a new field to the output Schema that is not connected to the input Schema. More...
template<typename T >
Key< T >	addMapping (Key< T > const &inputKey, bool doReplace=false)
	Add a new field to the output Schema that is a copy of a field in the input Schema. More...
template<typename T >
Key< T >	addMapping (Key< T > const &inputKey, Field< T > const &outputField, bool doReplace=false)
	Add a new mapped field to the output Schema with new descriptions. More...
template<typename T >
Key< T >	addMapping (Key< T > const &inputKey, std::string const &outputName, bool doReplace=true)
	Add a new mapped field to the output Schema with a new name. More...
template<typename T >
Key< T >	addMapping (Key< T > const &inputKey, char const *outputName, bool doReplace=true)=delete
	This deliberately deleted overload ensures we don't accidentally cast string literals to bool. More...
template<typename Predicate >
void	addMappingsWhere (Predicate predicate, bool doReplace=true)
	Add mappings for all fields that match criteria defined by a predicate. More...
void	addMinimalSchema (Schema const &minimal, bool doMap=true)
	Add the given minimal schema to the output schema. More...
void	invert ()
	Swap the input and output schemas in-place. More...
template<typename T >
bool	isMapped (Key< T > const &inputKey) const
	Return true if the given input Key is mapped to an output Key. More...
template<typename T >
Key< T >	getMapping (Key< T > const &inputKey) const
	Return the output Key corresponding to the given input Key, or raise NotFoundError. More...
template<typename F >
void	forEach (F &func) const
	Call the given functor for each key pair in the mapper. More...
template<typename F >
void	forEach (F const &func) const
	SchemaMapper ()
	Construct an empty mapper; useless unless you assign a fully-constructed one to it. More...
	SchemaMapper (Schema const &input, Schema const &output)
	Construct a mapper from the given input Schema and initial output Schema. More...
	SchemaMapper (Schema const &input, bool shareAliasMap=false)
	Construct a mapper from the given input Schema. More...
	SchemaMapper (SchemaMapper const &other)
	Copy construct (copy-on-write). More...
	SchemaMapper (SchemaMapper &&other)
SchemaMapper &	operator= (SchemaMapper const &other)
	Assignment (copy-on-write). More...
SchemaMapper &	operator= (SchemaMapper &&other)
	~SchemaMapper ()

Static Public Member Functions
static SchemaMapper	removeMinimalSchema (Schema const &input, Schema const &minimal)
	Create a mapper by removing fields from the front of a schema. More...
static std::vector< SchemaMapper >	join (std::vector< Schema > const &inputs, std::vector< std::string > const &prefixes=std::vector< std::string >())
	Combine a sequence of schemas into one, creating a SchemaMapper for each. More...

Detailed Description

A mapping between the keys of two Schemas, used to copy data between them.

SchemaMapper is initialized with its input Schema, and contains member functions to add mapped or unmapped fields to the output Schema.

Definition at line 21 of file SchemaMapper.h.

Constructor & Destructor Documentation

SchemaMapper() [1/5]

lsst::afw::table::SchemaMapper::SchemaMapper ( )

explicit

Construct an empty mapper; useless unless you assign a fully-constructed one to it.

Definition at line 105 of file SchemaMapper.cc.

: _impl(new Impl(Schema(), Schema())) {}

SchemaMapper() [2/5]

lsst::afw::table::SchemaMapper::SchemaMapper ( Schema const &  input, Schema const &  output  )

explicit

Construct a mapper from the given input Schema and initial output Schema.

Parameters

[in]	input	The Schema that fields will be mapped from.
[in]	output	The starting point for the Schema that fields will be mapped to (no mappings will be created automaticaly). Use addMapping() with doReplace=true to connect input fields to preexisting fields in the output schema.

Note that the addMapping() methods will not connect input schema fields to existing output schema fields unless doReplace=true; instead, these will by default append new fields to the output schema. So most often you'll want to start with an empty output schema and construct it as fields are mapped from the input schema, or be sure to always pass doReplace=true to addMapping.

Definition at line 111 of file SchemaMapper.cc.

: _impl(new Impl(input, output)) {}

SchemaMapper() [3/5]

lsst::afw::table::SchemaMapper::SchemaMapper ( Schema const &  input, bool  shareAliasMap = false  )

explicit

Construct a mapper from the given input Schema.

Parameters

[in]	input	The Schema that fields will be mapped from.
[in]	shareAliasMap	If true, install the input Schema's AliasMap in the output Schema.

Note that the addMapping() methods will not connect input schema fields to existing output schema fields unless doReplace=true; instead, these will by default append new fields to the output schema. So most often you'll want to start with an empty output schema and construct it as fields are mapped from the input schema, or be sure to always pass doReplace=true to addMapping.

The initial (empty) output schema will have the same version as the input schema, and they will share the same AliasMap (use editOutputSchema().disconnectAliases() to use a copy of the AliasMap).

Definition at line 113 of file SchemaMapper.cc.

                                                                  : _impl(new Impl(input, Schema())) {
    if (shareAliasMap) {
        editOutputSchema().setAliasMap(input.getAliasMap());
    }
}

SchemaMapper() [4/5]

lsst::afw::table::SchemaMapper::SchemaMapper

(

SchemaMapper const &

other

)

Copy construct (copy-on-write).

Definition at line 107 of file SchemaMapper.cc.

: _impl(new Impl(*other._impl)) {}

SchemaMapper() [5/5]

lsst::afw::table::SchemaMapper::SchemaMapper

(

SchemaMapper &&

other

)

Definition at line 109 of file SchemaMapper.cc.

: SchemaMapper(other) {}

~SchemaMapper()

lsst::afw::table::SchemaMapper::~SchemaMapper ( )

default

Member Function Documentation

addMapping() [1/4]

template<typename T >

Key< T > lsst::afw::table::SchemaMapper::addMapping	(	Key< T > const &	inputKey,
		bool	doReplace = false
	)

Add a new field to the output Schema that is a copy of a field in the input Schema.

If the input Key has already been mapped, the existing output Key will be reused but the associated Field in the output Schema will be reset to a copy of the input Field.

If doReplace=True and a field with same name already exists in the output schema, that field will be mapped instead of adding a new field to the output schema. If doReplace=false and a name conflict occurs, an exception will be thrown.

Definition at line 130 of file SchemaMapper.cc.

                                                                      {
    typename Impl::KeyPairMap::iterator i =
            std::find_if(_impl->_map.begin(), _impl->_map.end(), KeyPairCompareEqual<T>(inputKey));
    Field<T> inputField = _impl->_input.find(inputKey).field;
    if (i != _impl->_map.end()) {
        Key<T> const &outputKey = std::get<std::pair<Key<T>, Key<T>>>(*i).second;
        _impl->_output.replaceField(outputKey, inputField);
        return outputKey;
    } else {
        Key<T> outputKey = _impl->_output.addField(inputField, doReplace);
        _impl->_map.insert(i, std::make_pair(inputKey, outputKey));
        return outputKey;
    }
}

addMapping() [2/4]

template<typename T >

Key<T> lsst::afw::table::SchemaMapper::addMapping ( Key< T > const &  inputKey, char const *  outputName, bool  doReplace = true  )

delete

This deliberately deleted overload ensures we don't accidentally cast string literals to bool.

See DM-13787 for more information.

addMapping() [3/4]

template<typename T >

Key< T > lsst::afw::table::SchemaMapper::addMapping	(	Key< T > const &	inputKey,
		Field< T > const &	outputField,
		bool	doReplace = false
	)

Add a new mapped field to the output Schema with new descriptions.

If the input Key has already been mapped, the existing output Key will be reused but the associated Field will be replaced with the given one.

If doReplace=True and a field with same name already exists in the output schema, that field will be mapped instead of adding a new field to the output schema. If doReplace=false and a name conflict occurs, an exception will be thrown.

Definition at line 146 of file SchemaMapper.cc.

                                                                                             {
    typename Impl::KeyPairMap::iterator i =
            std::find_if(_impl->_map.begin(), _impl->_map.end(), KeyPairCompareEqual<T>(inputKey));
    if (i != _impl->_map.end()) {
        Key<T> const &outputKey = std::get<std::pair<Key<T>, Key<T>>>(*i).second;
        _impl->_output.replaceField(outputKey, field);
        return outputKey;
    } else {
        Key<T> outputKey = _impl->_output.addField(field, doReplace);
        _impl->_map.insert(i, std::make_pair(inputKey, outputKey));
        return outputKey;
    }
}

addMapping() [4/4]

template<typename T >

Key< T > lsst::afw::table::SchemaMapper::addMapping	(	Key< T > const &	inputKey,
		std::string const &	outputName,
		bool	doReplace = true
	)

Add a new mapped field to the output Schema with a new name.

If the input Key has already been mapped, the existing output Key will be reused but the associated Field will be replaced with one with the given name.

If doReplace=True and a field with same name already exists in the output schema, that field will be mapped instead of adding a new field to the output schema. If doReplace=false and a name conflict occurs, an exception will be thrown.

Definition at line 161 of file SchemaMapper.cc.

                                                                                                   {
    typename Impl::KeyPairMap::iterator i =
            std::find_if(_impl->_map.begin(), _impl->_map.end(), KeyPairCompareEqual<T>(inputKey));
    if (i != _impl->_map.end()) {
        Key<T> const &outputKey = std::get<std::pair<Key<T>, Key<T>>>(*i).second;
        Field<T> field = _impl->_output.find(outputKey).field;
        field = field.copyRenamed(outputName);
        _impl->_output.replaceField(outputKey, field);
        return outputKey;
    } else {
        Field<T> inputField = _impl->_input.find(inputKey).field;
        Field<T> outputField = inputField.copyRenamed(outputName);
        Key<T> outputKey = _impl->_output.addField(outputField, doReplace);
        _impl->_map.insert(i, std::make_pair(inputKey, outputKey));
        return outputKey;
    }
}

addMappingsWhere()

template<typename Predicate >

void lsst::afw::table::SchemaMapper::addMappingsWhere	(	Predicate	predicate,
		bool	doReplace = true
	)

Add mappings for all fields that match criteria defined by a predicate.

A mapping in the output Schema will be created for each SchemaItem 'i' in the input Schema such that 'predicate(i)' is true. Note that the predicate must have a templated and/or sufficiently overloaded operator() to match all supported field types, not just those present in the input Schema.

If doReplace=True and a field with same name already exists in the output schema, that field will be mapped instead of adding a new field to the output schema. If doReplace=false and a name conflict occurs, an exception will be thrown.

Definition at line 247 of file SchemaMapper.h.

                                                                       {
    _impl->_input.forEach(AddMappingsWhere<Predicate>(this, predicate, doReplace));
}

addMinimalSchema()

void lsst::afw::table::SchemaMapper::addMinimalSchema	(	Schema const &	minimal,
		bool	doMap = true
	)

Add the given minimal schema to the output schema.

This is intended to be used to ensure the output schema starts with some minimal schema. It must be called before any other fields are added to the output schema.

Parameters

[in]	minimal	Minimal schema to be added to the beginning of the output schema.
[in]	doMap	Whether to map minimal schema fields that are also present in the input schema.

Definition at line 179 of file SchemaMapper.cc.

                                                                     {
    if (getOutputSchema().getFieldCount() > 0) {
        throw LSST_EXCEPT(pex::exceptions::LogicError,
                          "Must add minimal schema to mapper before adding any other fields");
    }
    MapMinimalSchema f(this, doMap);
    minimal.forEach(f);
}

addOutputField()

template<typename T >

Key<T> lsst::afw::table::SchemaMapper::addOutputField ( Field< T > const &  newField, bool  doReplace = false  )

inline

Add a new field to the output Schema that is not connected to the input Schema.

Definition at line 34 of file SchemaMapper.h.

                                                                            {
        return _impl->_output.addField(newField, doReplace);
    }

editOutputSchema()

Schema& lsst::afw::table::SchemaMapper::editOutputSchema ( )

inline

Return a reference to the output schema that allows it to be modified in place.

Definition at line 30 of file SchemaMapper.h.

{ return _impl->_output; }

forEach() [1/2]

template<typename F >

void lsst::afw::table::SchemaMapper::forEach ( F &  func ) const

inline

Call the given functor for each key pair in the mapper.

Function objects should have a template and/or overloaded operator() that takes two Key objects with the same type:

struct Functor {
    template <typename T>
    void operator()(Key<T> const & input, Key<T> const & output) const;
};

The order of iteration is the same as the order in which mappings were added.

Definition at line 150 of file SchemaMapper.h.

                                {
        for (auto const & item : _impl->_map) {
            std::visit([&func](auto const & pair) { func(pair.first, pair.second); }, item);
        }
    }

forEach() [2/2]

template<typename F >

void lsst::afw::table::SchemaMapper::forEach ( F const &  func ) const

inline

Definition at line 156 of file SchemaMapper.h.

                                      {
        for (auto const & item : _impl->_map) {
            std::visit([&func](auto const & pair) { func(pair.first, pair.second); }, item);
        }
    }

getInputSchema()

Schema const lsst::afw::table::SchemaMapper::getInputSchema ( ) const

inline

Return the input schema (copy-on-write).

Definition at line 24 of file SchemaMapper.h.

{ return _impl->_input; }

getMapping()

template<typename T >

Key< T > lsst::afw::table::SchemaMapper::getMapping

(

Key< T > const &

inputKey

)

const

Return the output Key corresponding to the given input Key, or raise NotFoundError.

Definition at line 206 of file SchemaMapper.cc.

                                                            {
    typename Impl::KeyPairMap::iterator i =
            std::find_if(_impl->_map.begin(), _impl->_map.end(), KeyPairCompareEqual<T>(inputKey));
    if (i == _impl->_map.end()) {
        throw LSST_EXCEPT(lsst::pex::exceptions::NotFoundError, "Input Key is not mapped.");
    }
    return std::get<std::pair<Key<T>, Key<T>>>(*i).second;
}

getOutputSchema()

Schema const lsst::afw::table::SchemaMapper::getOutputSchema ( ) const

inline

Return the output schema (copy-on-write).

Definition at line 27 of file SchemaMapper.h.

{ return _impl->_output; }

invert()

void lsst::afw::table::SchemaMapper::invert

(

)

Swap the input and output schemas in-place.

Definition at line 195 of file SchemaMapper.cc.

                          {
    std::swap(_impl->_input, _impl->_output);
    std::for_each(_impl->_map.begin(), _impl->_map.end(), SwapKeyPair());
}

isMapped()

template<typename T >

bool lsst::afw::table::SchemaMapper::isMapped

(

Key< T > const &

inputKey

)

const

Return true if the given input Key is mapped to an output Key.

Definition at line 201 of file SchemaMapper.cc.

                                                        {
    return std::count_if(_impl->_map.begin(), _impl->_map.end(), KeyPairCompareEqual<T>(inputKey));
}

join()

std::vector< SchemaMapper > lsst::afw::table::SchemaMapper::join ( std::vector< Schema > const &  inputs, std::vector< std::string > const &  prefixes = std::vector<std::string>()  )

static

Combine a sequence of schemas into one, creating a SchemaMapper for each.

Parameters

[in]	inputs	A vector of input schemas to merge.
[in]	prefixes	An optional vector of prefixes for the output field names, either empty or of the same size as the inputs vector.

Each of the returned SchemaMappers has the same output schema.

Definition at line 215 of file SchemaMapper.cc.

                                                                                   {
    std::size_t const size = inputs.size();
    if (!prefixes.empty() && prefixes.size() != inputs.size()) {
        throw LSST_EXCEPT(
                pex::exceptions::LengthError,
                (boost::format("prefix vector size (%d) must be the same as input vector size (%d)") %
                 prefixes.size() % inputs.size())
                        .str());
    }
    std::vector<SchemaMapper> result;
    for (std::size_t i = 0; i < size; ++i) {
        result.emplace_back(inputs[i]);
    }
    for (std::size_t i = 0; i < size; ++i) {
        for (std::size_t j = 0; j < size; ++j) {
            if (i == j) {
                AddMapped functor(&result[j]);
                if (!prefixes.empty()) functor.prefix = prefixes[i];
                inputs[i].forEach(functor);
            } else {
                AddUnmapped functor(&result[j]);
                if (!prefixes.empty()) functor.prefix = prefixes[i];
                inputs[i].forEach(functor);
            }
        }
    }
    return result;
}

operator=() [1/2]

SchemaMapper & lsst::afw::table::SchemaMapper::operator=

(

SchemaMapper &&

other

)

Definition at line 125 of file SchemaMapper.cc.

{ return *this = other; }

operator=() [2/2]

SchemaMapper & lsst::afw::table::SchemaMapper::operator=

(

SchemaMapper const &

other

)

Assignment (copy-on-write).

Definition at line 119 of file SchemaMapper.cc.

                                                               {
    std::unique_ptr<Impl> tmp(new Impl(*other._impl));
    _impl.swap(tmp);
    return *this;
}

removeMinimalSchema()

SchemaMapper lsst::afw::table::SchemaMapper::removeMinimalSchema ( Schema const &  input, Schema const &  minimal  )

static

Create a mapper by removing fields from the front of a schema.

The returned mapper maps all fields in the input schema to all fields that are not in the minimal schema (compared by keys, so the overlap must appear at the beginning of the input schema).

Parameters

[in]	input	Input schema for the mapper.
[in]	minimal	The minimal schema the input schema starts with.

Definition at line 188 of file SchemaMapper.cc.

                                                                                         {
    SchemaMapper mapper(input);
    RemoveMinimalSchema f(&mapper, minimal);
    input.forEach(f);
    return mapper;
}

---

The documentation for this class was generated from the following files:

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/afw/22.0.1-42-gca6935d93+ba5e5ca3eb/include/lsst/afw/table/SchemaMapper.h
• /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/afw/22.0.1-42-gca6935d93+ba5e5ca3eb/src/table/SchemaMapper.cc