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Facilities for evaluating recommender algorithms.
/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.grouplens.lenskit.util.table;
import com.google.common.collect.ImmutableList;
import it.unimi.dsi.fastutil.objects.Object2IntMap;
import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
import java.util.Collection;
import java.util.List;
/**
* A layout for a table to be written. Specifies the columns in the table. Column names
* must be unique.
*
* @author GroupLens Research
* @since 0.10
*/
public class TableLayout {
private final List names;
private final Object2IntMap indexes;
TableLayout(Collection colNames) {
names = ImmutableList.copyOf(colNames);
indexes = new Object2IntOpenHashMap(names.size());
for (String col: names) {
indexes.put(col, indexes.size());
}
// set default return to -1, so we get an illegal index when looking up a nonexistent column
indexes.defaultReturnValue(-1);
}
/**
* Get the headers of the columns.
*
* @return The headers of the columns in the table layout.
*/
public List getColumns() {
return names;
}
/**
* Get the index of a particular column.
*
* @param col The column.
* @return The index of the specified column, starting from 0.
* @throws IllegalArgumentException if the column is not in the layout.
*/
public int columnIndex(String col) {
int idx = indexes.getInt(col);
if (idx < 0) {
throw new IllegalArgumentException(col + ": no such column");
} else {
return idx;
}
}
/**
* Get the number of columns in this layout.
*
* @return The number of columns in the table layout.
*/
public int getColumnCount() {
return names.size();
}
}
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