org.datavec.api.transform.schema

Class Schema

java.lang.Object

org.datavec.api.transform.schema.Schema

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

SequenceSchema

public class Schema
extends Object
implements Serializable

A Schema defines the layout of tabular data. Specifically, it contains names f or each column, as well as details of types (Integer, String, Long, Double, etc).
Type information for each column may optionally include restrictions on the allowable values for each column.

See also: SequenceSchema

Author:

Alex Black

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Schema.Builder

Constructor Summary

Constructors

Modifier	Constructor and Description
	Schema(List<ColumnMetaData> columnMetaData) Create a schema based on the given metadata
protected	Schema(Schema.Builder builder)

Method Summary

Modifier and Type	Method and Description
List<ColumnMetaData>	differences(Schema schema) Compute the difference in ColumnMetaData between this schema and the passed in schema.
static Schema	fromJson(String json) Create a schema from a given json string
static Schema	fromYaml(String yaml) Create a schema from the given yaml string
List<ColumnMetaData>	getColumnMetaData() Returns a copy of the underlying schema ColumnMetaData
List<String>	getColumnNames() Return a copy of the list column names
List<ColumnType>	getColumnTypes() A copy of the list of ColumnType for this schema
int	getIndexOfColumn(String columnName) Returns the index for the given column name
int[]	getIndexOfColumns(Collection<String> columnNames) Return the indices of the columns, given their namess
int[]	getIndexOfColumns(String... columnNames) Return the indices of the columns, given their namess
ColumnMetaData	getMetaData(int column) Returns the ColumnMetaData at the specified column index
ColumnMetaData	getMetaData(String column) Retrieve the metadata for the given column name
String	getName(int column) Returns the name of a given column at the specified index
ColumnType	getType(int column) Returns the ColumnType for the column at the specified index
ColumnType	getType(String columnName) Returns the ColumnType for the column at the specified index
boolean	hasColumn(String columnName) Determine if the schema has a column with the specified name
static Schema	infer(List<Writable> record) Infers a schema based on the record.
static Schema	inferMultiple(List<List<Writable>> record) Infers a schema based on the record.
Schema	newSchema(List<ColumnMetaData> columnMetaData) Create a new schema based on the new metadata
int	numColumns() Returns the number of columns or fields for this schema
boolean	sameTypes(Schema schema) Returns true if the given schema has the same types at each index
String	toJson() Serialize this schema to json
String	toString()
String	toYaml() Serialize this schema to yaml

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Schema

protected Schema(Schema.Builder builder)

Schema

public Schema(List<ColumnMetaData> columnMetaData)

Create a schema based on the given metadata

Parameters:

columnMetaData - the metadata to create the schema from

Method Detail

sameTypes

public boolean sameTypes(Schema schema)

Returns true if the given schema has the same types at each index

Parameters:

schema - the schema to compare the types to

Returns:

true if the schema has the same types at every index as this one,false otherwise

differences

public List<ColumnMetaData> differences(Schema schema)

Compute the difference in ColumnMetaData between this schema and the passed in schema. This is useful during the TransformProcess to identify what a process will do to a given Schema.

Parameters:

schema - the schema to compute the difference for

Returns:

the metadata that is different (in order) between this schema and the other schema

newSchema

public Schema newSchema(List<ColumnMetaData> columnMetaData)

Create a new schema based on the new metadata

Parameters:

columnMetaData - the new metadata to create the schema from

Returns:

the new schema

numColumns

public int numColumns()

Returns the number of columns or fields for this schema

Returns:

the number of columns or fields for this schema

getName

public String getName(int column)

Returns the name of a given column at the specified index

Parameters:

column - the index of the column to get the name for

Returns:

the name of the column at the specified index

getType

public ColumnType getType(int column)

Returns the ColumnType for the column at the specified index

Parameters:

column - the index of the column to get the type for

Returns:

the type of the column to at the specified inde

getType

public ColumnType getType(String columnName)

Returns the ColumnType for the column at the specified index

Parameters:

columnName - the index of the column to get the type for

Returns:

the type of the column to at the specified inde

getMetaData

public ColumnMetaData getMetaData(int column)

Returns the ColumnMetaData at the specified column index

Parameters:

column - the index to get the metadata for

Returns:

the metadata at ths specified index

getMetaData

public ColumnMetaData getMetaData(String column)

Retrieve the metadata for the given column name

Parameters:

column - the name of the column to get metadata for

Returns:

the metadata for the given column name

getColumnNames

public List<String> getColumnNames()

Return a copy of the list column names

Returns:

a copy of the list of column names for this schema

getColumnTypes

public List<ColumnType> getColumnTypes()

A copy of the list of ColumnType for this schema

Returns:

the list of column types in order based on column index for this schema

getColumnMetaData

public List<ColumnMetaData> getColumnMetaData()

Returns a copy of the underlying schema ColumnMetaData

Returns:

the list of schema metadata

getIndexOfColumn

public int getIndexOfColumn(String columnName)

Returns the index for the given column name

Parameters:

columnName - the column name to get the index for

Returns:

the index of the given column name for the schema

getIndexOfColumns

public int[] getIndexOfColumns(Collection<String> columnNames)

Return the indices of the columns, given their namess

Parameters:

columnNames - Name of the columns to get indices for

Returns:

Column indexes

getIndexOfColumns

public int[] getIndexOfColumns(String... columnNames)

Return the indices of the columns, given their namess

Parameters:

columnNames - Name of the columns to get indices for

Returns:

Column indexes

hasColumn

public boolean hasColumn(String columnName)

Determine if the schema has a column with the specified name

Parameters:

columnName - Name to see if the column exists

Returns:

True if a column exists for that name, false otherwise

toString

public String toString()

Overrides:

toString in class Object

toJson

public String toJson()

Serialize this schema to json

Returns:

a json representation of this schema

toYaml

public String toYaml()

Serialize this schema to yaml

Returns:

the yaml representation of this schema

fromJson

public static Schema fromJson(String json)

Create a schema from a given json string

Parameters:

json - the json to create the schema from

Returns:

the created schema based on the json

fromYaml

public static Schema fromYaml(String yaml)

Create a schema from the given yaml string

Parameters:

yaml - the yaml to create the schema from

Returns:

the created schema based on the yaml

inferMultiple

public static Schema inferMultiple(List<List<Writable>> record)

Infers a schema based on the record. The column names are based on indexing.

Parameters:

record - the record to infer from

Returns:

the infered schema

infer

public static Schema infer(List<Writable> record)

Infers a schema based on the record. The column names are based on indexing.

Parameters:

record - the record to infer from

Returns:

the infered schema