How to make a CombinedChart have two different scales on MPAndroidChart?

Question

I have a CombinedChart and I would like that LineChart will take left axis as reference and BarChart will take right axis as reference but I could not get it out.

I am trying the following code:

barDataSet.setAxisDependency(YAxis.AxisDependency.RIGHT);
lineDataSet.setAxisDependency(YAxis.AxisDependency.LEFT);

but now both charts (LineChart and BarChart) are on the left (mixing them and right axis have disappeared).

Left and right axis have different granularity.

How can I properly make that each chart takes as reference one different Y axis (left or right respectively)?

Thanks in advance!

Answer 1

This is certainly possible in MPAndroidChart version 3.0.2.

As you can observe from the screenshot below, the LineDataSet has AxisDependency.LEFT (scaled from 0 - 21) while the BarDataSet has AxisDependency.RIGHT (scaled from 0 - 50) and, as required, they have different granularity:

Here is a proof of concept for generating the above chart that is a simple adaptation of the example project on GitHub:

import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.WindowManager;

import com.github.mikephil.charting.charts.CombinedChart;
import com.github.mikephil.charting.charts.CombinedChart.DrawOrder;
import com.github.mikephil.charting.components.AxisBase;
import com.github.mikephil.charting.components.Legend;
import com.github.mikephil.charting.components.XAxis;
import com.github.mikephil.charting.components.XAxis.XAxisPosition;
import com.github.mikephil.charting.components.YAxis;
import com.github.mikephil.charting.data.BarData;
import com.github.mikephil.charting.data.BarDataSet;
import com.github.mikephil.charting.data.BarEntry;
import com.github.mikephil.charting.data.CombinedData;
import com.github.mikephil.charting.data.Entry;
import com.github.mikephil.charting.data.LineData;
import com.github.mikephil.charting.data.LineDataSet;
import com.github.mikephil.charting.formatter.IAxisValueFormatter;

import java.util.ArrayList;

public class CombinedChartActivity extends FragmentActivity {

    private String[] mMonths = new String[] {
            "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Okt", "Nov", "Dec"
    };

    private CombinedChart mChart;
    private final int itemcount = 12;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_combined);

        mChart = (CombinedChart) findViewById(R.id.chart1);
        mChart.getDescription().setEnabled(false);
        mChart.setBackgroundColor(Color.WHITE);
        mChart.setDrawGridBackground(false);
        mChart.setDrawBarShadow(false);
        mChart.setHighlightFullBarEnabled(false);

        mChart.setDrawOrder(new DrawOrder[]{
                DrawOrder.BAR, DrawOrder.BUBBLE, DrawOrder.CANDLE, DrawOrder.LINE, DrawOrder.SCATTER
        });

        Legend l = mChart.getLegend();
        l.setWordWrapEnabled(true);
        l.setVerticalAlignment(Legend.LegendVerticalAlignment.BOTTOM);
        l.setHorizontalAlignment(Legend.LegendHorizontalAlignment.CENTER);
        l.setOrientation(Legend.LegendOrientation.HORIZONTAL);
        l.setDrawInside(false);

        YAxis rightAxis = mChart.getAxisRight();
        rightAxis.setDrawGridLines(false);
        rightAxis.setGranularity(10f);
        rightAxis.setAxisMinimum(0f);

        YAxis leftAxis = mChart.getAxisLeft();
        leftAxis.setDrawGridLines(false);
        rightAxis.setGranularity(1f);
        leftAxis.setAxisMinimum(0f);

        XAxis xAxis = mChart.getXAxis();
        xAxis.setPosition(XAxisPosition.BOTH_SIDED);
        xAxis.setAxisMinimum(0f);
        xAxis.setGranularity(1f);
        xAxis.setValueFormatter(new IAxisValueFormatter() {
            @Override
            public String getFormattedValue(float value, AxisBase axis) {
                return mMonths[(int) value % mMonths.length];
            }
        });

        CombinedData data = new CombinedData();

        data.setData(generateLineData());
        data.setData(generateBarData());

        xAxis.setAxisMaximum(data.getXMax() + 0.25f);

        mChart.setData(data);
        mChart.invalidate();
    }

    private LineData generateLineData() {

        LineData d = new LineData();

        ArrayList<Entry> entries = new ArrayList<Entry>();

        for (int index = 0; index < itemcount; index++)
            entries.add(new Entry(index + 0.5f, getRandom(15, 5)));

        LineDataSet set = new LineDataSet(entries, "Line DataSet");
        set.setColor(Color.rgb(0,100,0));
        set.setLineWidth(2.5f);
        set.setCircleColor(Color.rgb(0,100,0));
        set.setCircleRadius(5f);
        set.setFillColor(Color.rgb(0,100,0));
        set.setMode(LineDataSet.Mode.CUBIC_BEZIER);
        set.setDrawValues(true);
        set.setValueTextSize(10f);
        set.setValueTextColor(Color.rgb(0,100,0));

        set.setAxisDependency(YAxis.AxisDependency.LEFT);
        d.addDataSet(set);

        return d;
    }

    private BarData generateBarData() {
        ArrayList<BarEntry> entries = new ArrayList<BarEntry>();

        for (int index = 0; index < itemcount; index++) {
            entries.add(new BarEntry(index, getRandom(25, 25)));
        }

        BarDataSet set = new BarDataSet(entries, "Bar DataSet");
        set.setColor(Color.rgb(60, 220, 78));
        set.setValueTextColor(Color.rgb(60, 220, 78));
        set.setValueTextSize(10f);
        set.setAxisDependency(YAxis.AxisDependency.RIGHT);

        return new BarData(set);
    }

    private float getRandom(float range, float startsfrom) {
        return (float) (Math.random() * range) + startsfrom;
    }
}