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High-performance Java Dataframe with integrated columnar storage (fork of tablesaw)

There is a newer version: 0.9.1

package org.datavec.dataframe.mapping;

import org.datavec.dataframe.api.FloatColumn;
import org.datavec.dataframe.api.IntColumn;
import org.datavec.dataframe.api.ShortColumn;
import org.datavec.dataframe.columns.Column;
import org.datavec.dataframe.columns.ShortColumnUtils;

/**
 *
 */
public interface ShortMapUtils extends ShortColumnUtils {

    default IntColumn plus(ShortColumn... columns) {

        // TODO(lwhite): Assert all columns are the same size.
        String nString = names(columns);
        String name = String.format("sum(%s)", nString);
        IntColumn newColumn = IntColumn.create(name);

        for (int r = 0; r < columns[0].size(); r++) {
            int result = 0;
            for (ShortColumn column : columns) {
                result = result + column.get(r);
            }
            newColumn.add(result);
        }
        return newColumn;
    }

    // TODO(lwhite): make this a shared utility
    default String names(ShortColumn[] columns) {
        StringBuilder builder = new StringBuilder();
        int count = 0;
        for (Column column : columns) {
            builder.append(column.name());
            if (count < columns.length - 1) {
                builder.append(", ");
            }
            count++;
        }
        return builder.toString();
    }

    /**
     * Return the elements of this column as the ratios of their value and the sum of all
     * elements
     */
    default FloatColumn asRatio() {
        FloatColumn pctColumn = new FloatColumn(name() + " percents");
        float total = sum();
        for (short next : this) {
            if (total != 0) {
                pctColumn.add((float) next / total);
            } else {
                pctColumn.add(FloatColumn.MISSING_VALUE);
            }

        }
        return pctColumn;
    }

    /**
     * Return the elements of this column as the percentages of their value relative to the sum of all
     * elements
     */
    default FloatColumn asPercent() {
        FloatColumn pctColumn = new FloatColumn(name() + " percents");
        float total = sum();
        for (short next : this) {
            if (total != 0) {
                pctColumn.add(((float) next / total) * 100);
            } else {
                pctColumn.add(FloatColumn.MISSING_VALUE);
            }
        }
        return pctColumn;
    }

    long sum();
}