/**
* returns a subset of this column with entried from rows indicated by <code>indices</code>.
*
* @param indices row numbers to include in the returned subset.
* @return a subset of this column, including rows indicated by <code>indices</code>.
*/
public Column getSubset(int[] indices) {
SparseObjectColumn retVal = new SparseObjectColumn(indices.length);
for (int i = 0; i < indices.length; i++) {
if (elements.containsKey(indices[i])) {
// XIAOLEI
// retVal.setObject(getObject(indices[i]), indices[i]);
retVal.setObject(getObject(indices[i]), i);
}
}
super.getSubset(retVal, indices);
return retVal;
}
/**
* performs a deep copy of this SparseObjectColumn returns an exact copy of this
* SparseObjectColumn
*
* @return a SparseObjectColumn object which is a deep copy of this SparseObjectColumn.
*/
public Column copy() {
SparseObjectColumn retVal;
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(this);
byte buf[] = baos.toByteArray();
oos.close();
ByteArrayInputStream bais = new ByteArrayInputStream(buf);
ObjectInputStream ois = new ObjectInputStream(bais);
retVal = (SparseObjectColumn) ois.readObject();
ois.close();
return retVal;
} catch (Exception e) {
retVal = new SparseObjectColumn();
retVal.copy(this);
return retVal;
}
}
/**
* Returns a SparseObjectColumn that holds only the data from rows <code>
* pos</code> through <code>pos+len</code>
*
* @param pos the row number which is the beginning of the subset
* @param len number of consequetive rows after <code>pos</code> that are to be included in the
* subset.
* @return a SparseObjectColumn with the data from rows <code>pos</code> through <code>pos+len
* </code>
*/
public Column getSubset(int pos, int len) {
SparseObjectColumn subCol = new SparseObjectColumn();
subCol.elements = (VIntObjectHashMap) elements.getSubset(pos, len);
getSubset(subCol, pos, len);
return subCol;
/*
//the map to hold the data of the subset
VIntObjectHashMap tempMap = new VIntObjectHashMap(len);
//for each Object from pos till pos+len
for (int i=0; i<len; i++)
//if a value is mapped to current inspected row number
if(elements.containsKey(pos+i))
//put it in the new map
tempMap.put(pos+i, getObject(pos+i));
SparseObjectColumn subCol = new SparseObjectColumn(); //the returned value
super.copy(subCol); //copying general attributes
//activating copy method in order to have a deep copy of the subset
subCol.elements = tempMap.copy(); //linking the data to the returned value
return subCol;
*/
}
/**
* Reorders the data stored in this column in a new column. Does not change this column.
*
* <p>Algorithm: copy this column into the returned vlaue. for each pair (key, val) in <code>
* newOrder</code>, if val is a valid row in this column, put the value mapped to it in row no.
* key in the returned values.
*
* @param newOrder - an int to int hashmap, defining the new order for the returned column.
* @return a SparseObjectColumn ordered according to <code>newOrder</code>.
*/
public Column reorderRows(VIntIntHashMap newOrder) {
SparseObjectColumn retVal = new SparseObjectColumn();
retVal.elements = (VIntObjectHashMap) elements.reorder(newOrder);
reorderRows(retVal, newOrder);
return retVal;
}
