public static BindingsImpl Create(ModelLoadContext ctx, DataViewSchema input,
IHostEnvironment env, ISchemaBindableMapper bindable,
Func <DataViewType, bool> outputTypeMatches, Func <DataViewType, ISchemaBoundRowMapper, DataViewType> getPredColType)
{
Contracts.AssertValue(env);
env.AssertValue(ctx);
// *** Binary format ***
// <base info>
// int: id of the scores column kind (metadata output)
// int: id of the column used for deriving the predicted label column
string suffix;
var roles = LoadBaseInfo(ctx, out suffix);
string scoreKind = ctx.LoadNonEmptyString();
string scoreCol = ctx.LoadNonEmptyString();
var mapper = bindable.Bind(env, new RoleMappedSchema(input, roles));
var rowMapper = mapper as ISchemaBoundRowMapper;
env.CheckParam(rowMapper != null, nameof(bindable), "Bindable expected to be an " + nameof(ISchemaBindableMapper) + "!");
// Find the score column of the mapper.
int scoreColIndex;
env.CheckDecode(mapper.OutputSchema.TryGetColumnIndex(scoreCol, out scoreColIndex));
var scoreType = mapper.OutputSchema[scoreColIndex].Type;
env.CheckDecode(outputTypeMatches(scoreType));
var predColType = getPredColType(scoreType, rowMapper);
return(new BindingsImpl(input, rowMapper, suffix, scoreKind, false, scoreColIndex, predColType));
}
/// <summary>
/// Gets a cached prediction engine or creates a new one if not cached
/// </summary>
private BatchPredictionEngine <SarUsageEvent, SarScoreResult> GetOrCreateBatchPredictionEngine(
IList <SarUsageEvent> usageItems, SarScoringArguments sarScoringArguments)
{
var arguments = new RecommenderScorerTransform.Arguments
{
// round the recommendations count to optimize engine cache
recommendationCount = GetRoundedNumberOfResults(sarScoringArguments.RecommendationCount),
includeHistory = sarScoringArguments.IncludeHistory
};
// create a data column mapping
var dataColumnMapping = new Dictionary <RoleMappedSchema.ColumnRole, string>
{
{ new RoleMappedSchema.ColumnRole("Item"), "Item" },
{ new RoleMappedSchema.ColumnRole("User"), "user" }
};
string weightColumn = null;
if (sarScoringArguments.ReferenceDate.HasValue)
{
// rounding the reference date to the beginning of next day to optimize engine cache
DateTime referenceDate = sarScoringArguments.ReferenceDate.Value.Date + TimeSpan.FromDays(1);
arguments.referenceDate = referenceDate.ToString("s");
if (sarScoringArguments.Decay.HasValue)
{
arguments.decay = sarScoringArguments.Decay.Value.TotalDays;
}
dataColumnMapping.Add(new RoleMappedSchema.ColumnRole("Date"), "date");
weightColumn = "weight";
}
// create an engine cache key
string cacheKey = $"{arguments.recommendationCount}|{arguments.includeHistory}|{arguments.referenceDate}|{arguments.decay}";
_tracer.TraceVerbose("Trying to find the engine in the cache");
var engine = _enginesCache.Get(cacheKey) as BatchPredictionEngine <SarUsageEvent, SarScoreResult>;
if (engine == null)
{
_tracer.TraceInformation("Engine is not cached - creating a new engine");
IDataView pipeline = _environment.CreateDataView(usageItems, _usageDataSchema);
RoleMappedData usageDataMappedData = _environment.CreateExamples(pipeline, null, weight: weightColumn, custom: dataColumnMapping);
ISchemaBindableMapper mapper = RecommenderScorerTransform.Create(_environment, arguments, _recommender);
ISchemaBoundMapper boundMapper = mapper.Bind(_environment, usageDataMappedData.Schema);
IDataScorerTransform scorer = RecommenderScorerTransform.Create(
_environment, arguments, pipeline, boundMapper, null);
engine = _environment.CreateBatchPredictionEngine <SarUsageEvent, SarScoreResult>(scorer, false, _usageDataSchema);
bool result = _enginesCache.Add(cacheKey, engine, new CacheItemPolicy {
SlidingExpiration = TimeSpan.FromDays(1)
});
_tracer.TraceVerbose($"Addition of engine to the cache resulted with '{result}'");
}
return(engine);
}
ISchemaBoundMapper ISchemaBindableMapper.Bind(IHostEnvironment env, RoleMappedSchema schema)
{
var innerBound = _bindable.Bind(env, schema);
if (_canWrap != null && !_canWrap(innerBound, _type))
{
return(innerBound);
}
Contracts.Assert(innerBound is ISchemaBoundRowMapper);
return(Utils.MarshalInvoke(CreateBound <int>, _type.ItemType.RawType, env, (ISchemaBoundRowMapper)innerBound, _type, _getter, _metadataKind, _canWrap));
}
public BindingsImpl ApplyToSchema(DataViewSchema input, ISchemaBindableMapper bindable, IHostEnvironment env)
{
Contracts.AssertValue(env);
env.AssertValue(input);
env.AssertValue(bindable);
string scoreCol = RowMapper.OutputSchema[ScoreColumnIndex].Name;
var schema = new RoleMappedSchema(input, RowMapper.GetInputColumnRoles());
// Checks compatibility of the predictor input types.
var mapper = bindable.Bind(env, schema);
var rowMapper = mapper as ISchemaBoundRowMapper;
env.CheckParam(rowMapper != null, nameof(bindable), "Mapper must implement ISchemaBoundRowMapper");
int mapperScoreColumn;
bool tmp = rowMapper.OutputSchema.TryGetColumnIndex(scoreCol, out mapperScoreColumn);
env.Check(tmp, "Mapper doesn't have expected score column");
return new BindingsImpl(input, rowMapper, Suffix, ScoreColumnKind, true, mapperScoreColumn, PredColType);
}
/// <summary>
/// Create the bindings given the env, bindable, input schema, column roles, and column name suffix.
/// </summary>
private static Bindings Create(IHostEnvironment env, ISchemaBindableMapper bindable, DataViewSchema input,
IEnumerable <KeyValuePair <RoleMappedSchema.ColumnRole, string> > roles, string suffix, bool user = true)
{
Contracts.AssertValue(env);
Contracts.AssertValue(bindable);
Contracts.AssertValue(input);
Contracts.AssertValue(roles);
Contracts.AssertValueOrNull(suffix);
var mapper = bindable.Bind(env, new RoleMappedSchema(input, roles));
// We don't actually depend on this invariant, but if this assert fires it means the bindable
// did the wrong thing.
Contracts.Assert(mapper.InputRoleMappedSchema.Schema == input);
var rowMapper = mapper as ISchemaBoundRowMapper;
Contracts.Check(rowMapper != null, "Predictor expected to be a RowMapper!");
return(Create(input, rowMapper, suffix, user));
}
