I have a pretty complex nested structure with several levels. So in order to
create it I use SQLContext.createDataFrame method and provide specific Rows
with specific StrucTypes, both of which I build myself.
To build a Row I iterate over my values and literally build a Row.
List<Object> row = new LinkedList<>();
for (Attribute attributeNode : attributeNodes()) {
final String name = attributeNode.getName();
if (name.equals(“attr-simple-1")) {
row.add(obj.getValue());
} else if (name.equals("attr-nested-1")) {
List<Object> rowAttributes = new LinkedList<>();
for (Attribute node : attributeNode.getAttributes()) {
String nodeName = node.getName();
if (obj.getSimpleAttributeNames().contains(nodeName)) {
rowAttributes.add( value );
} else if ( nested ) {
rowAttributes.add( // recursion );
} else rowAttributes.add(null);
}
row.add(new GenericRow(rowAttributes.toArray(new
Object[rowAttributes.size()])));
} else {
row.add(null);
}
}
return new GenericRow(row.toArray(new Object[row.size()]));
To build StructType I create an array of StructFields
List<StructField> structFields = ...
if (attribute.isSingleValue()) {
structFields.add(DataTypes.createStructField(attribute.getName(),
dataType(attribute), true));
} else {
structFields.add(DataTypes.createStructField(attribute.getName(),
DataTypes.createArrayType(dataType(attribute)), true));
}
and then
DataTypes.createStructType(structFields);
dataType() is a method to get corresponding o.a.spark.sql.types.DataType;
If you have to create Row with another structure you just can map original Row
into the one with the new structure and build corresponding StructType.
Although if you find a simpler way, I’d really like to know about that.
On 07 Aug 2015, at 12:43, Rishabh Bhardwaj <rbnex...@gmail.com> wrote:
> I am doing it by creating a new data frame out of the fields to be nested and
> then join with the original DF.
> Looking for some optimized solution here.
>
> On Fri, Aug 7, 2015 at 2:06 PM, Rishabh Bhardwaj <rbnex...@gmail.com> wrote:
> Hi all,
>
> I want to have some nesting structure from the existing columns of the
> dataframe.
> For that,,I am trying to transform a DF in the following way,but couldn't do
> it.
>
> scala> df.printSchema
> root
> |-- a: string (nullable = true)
> |-- b: string (nullable = true)
> |-- c: string (nullable = true)
> |-- d: string (nullable = true)
> |-- e: string (nullable = true)
> |-- f: string (nullable = true)
>
> To
>
> scala> newDF.printSchema
> root
> |-- a: string (nullable = true)
> |-- b: string (nullable = true)
> |-- c: string (nullable = true)
> |-- newCol: struct (nullable = true)
> | |-- d: string (nullable = true)
> | |-- e: string (nullable = true)
>
>
> help me.
>
> Regards,
> Rishabh.
>
Eugene Morozov
fathers...@list.ru
