How do I rotate the coordinate plane and y-axis labels in Java for data visualization?

Rotating Coordinate Plane for Data and Text in Java

This issue deals with challenges in plotting data points and rotating labels on the y-axis of a data plot. The provided code defines basic structures for plotting data and labels, but it encounters two difficulties:

• Data points are plotted incorrectly due to the origin and y-axis orientation.
• Y-axis labels are not visible on the screen.

Resolving the Issues

To address these issues, let's focus on the following modifications:

1. Rotating the Coordinate Plane

We can rotate the coordinate plane to align with the new origin (bottom-left corner of the blue rectangle) and invert the y-axis using the following code:

<code class="java">g2d.translate(leftStartPlotWindow, blueTop);//translate origin to bottom-left corner of blue rectangle
g2d.scale(1, -1);//invert the y-axis</code>

2. Plotting Data

We adjust the data to fit the rotated coordinate plane by multiplying it by a scalar:

<code class="java">double Scalar = blueWidth/maxPlot;
ArrayList<Double> scaledDiffs = new ArrayList<>();
for(int e = 0;e<myDiffs.size();e++){scaledDiffs.add(myDiffs.get(e)*Scalar);}</code>

3. Rotating Text for Y-Axis Labels

To rotate labels on the y-axis, we use the following code:

<code class="java">g2d.rotate(Math.toRadians(-90), 0, 0);//rotate text 90 degrees counter-clockwise
g.drawString(yString, -(height/2)-(yStrWidth/2), yStrHeight);
g2d.rotate(Math.toRadians(+90), 0, 0);//rotate text 90 degrees clockwise</code>

Complete Code

The modified code with these adjustments should resolve the issues:

DataGUI.java

<code class="java">//... Previous code omitted for brevity
import java.awt.geom.AffineTransform;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.List;

class DataGUI extends JFrame{
//... Previous code omitted for brevity

    @Override
    public void paint(Graphics g) {
        // ... Previous code omitted for brevity
        int height = getHeight();
        int width = getWidth();
        ins = getInsets();

        // Obtain data about graphics environment and text
        Graphics2D g2d = (Graphics2D) g;
        FontMetrics fontMetrics = g2d.getFontMetrics();
        String xString = "x-axis Label";
        int xStrWidth = fontMetrics.stringWidth(xString);
        int xStrHeight = fontMetrics.getHeight();

        // Set parameters for the inner rectangle
        int hPad = 10;
        int vPad = 6;
        int testLeftStartPlotWindow = ins.left + 5 + (3 * yStrHeight);
        int testInnerWidth = width - testLeftStartPlotWindow - ins.right - hPad;

        // Find minimum and maximum values
        getMaxMinDiffs();
        getMaxPlotVal();

        // Determine the maximum number of ticks for the axes
        double increment = 5.0;
        int numTicks = (int) (maxPlot / increment);
        int remainder = testInnerWidth % numTicks;
        int leftStartPlotWindow = testLeftStartPlotWindow - remainder;

        // Calculate the bottom padding and blue rectangle dimensions
        int bottomPad = (3 * xStrHeight) - vPad;
        int blueTop = ins.bottom + (vPad / 2) + titleStrHeight;
        int blueHeight = height - bottomPad - blueTop;
        int blueWidth = blueHeight;
        int blueBottom = blueHeight + blueTop;

        // Start drawing
        // ... Previous code omitted for brevity

        // Scale the diffs to fit the window
        double Scalar = blueWidth / maxPlot;
        List<Double> scaledDiffs = new ArrayList<>();
        for (Double myDiff : myDiffs) {
            scaledDiffs.add(myDiff * Scalar);
        }

        // Rotate the graphics context for plotting data
        AffineTransform at = g2d.getTransform();
        g2d.translate(leftStartPlotWindow, blueTop);
        g2d.scale(1, -1);

        // Plot the scaled diffs
        for (int w = 0; w < scaledDiffs.size(); w++) {
            if (w > 0) {
                double prior = scaledDiffs.get(w - 1);
                int priorInt = (int) prior;
                double current = scaledDiffs.get(w);
                int currentInt = (int) current;
                g2d.drawOval(priorInt, currentInt, 4, 4);
            }
        }

        // Restore the transform for conventional rendering
        g2d.setTransform(at);
        // ... Rest of the code omitted for brevity
    }

    // ... Previous code omitted for brevity
}</code>

DataPanel.java

<code class="java">//... Previous code omitted for brevity

@Override
protected void paintComponent(Graphics g) {
//... Previous code omitted for brevity

int blueTop = ins.bottom+(vPad/2)+titleStrHeight;
int blueHeight = height-bottomPad-blueTop;
int blueWidth = blueHeight;
int blueBottom = blueHeight+blueTop;

//... Previous code omitted for brevity

// Rotate the graphics context for y-axis labels
g2d.rotate(Math.toRadians(-90), 0, 0);
g.drawString(yString, -(height/2)-(yStrWidth/2), yStrHeight);

// Restore the graphics context for normal rendering
g2d.rotate(Math.toRadians(+90), 0, 0);

//... Previous code omitted for brevity
}</code>

Additional Resource

For further information on graphics transformations, refer to:

• [Java 2D Graphics](https://docs.oracle.com/javase/8/docs/technotes/guides/2d/index.html)

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