如何在Java中旋转坐标平面和y轴标签以实现数据可视化？

在 Java 中旋转数据和文本的坐标平面

此问题解决了在 y 轴上绘制数据点和旋转标签的挑战数据图。提供的代码定义了绘制数据和标签的基本结构，但遇到了两个困难：

• 由于原点和 y 轴方向，数据点绘制不正确。
• Y-轴标签在屏幕上不可见。

解决问题

为了解决这些问题，让我们重点进行以下修改：

1.旋转坐标平面

我们可以旋转坐标平面以与新原点（蓝色矩形的左下角）对齐，并使用以下代码反转 y 轴：

<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。绘制数据

我们通过将数据乘以标量来调整数据以适合旋转的坐标平面：

<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。旋转 Y 轴标签的文本

要在 y 轴上旋转标签，我们使用以下代码：

<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>

完整代码

经过这些调整的修改后的代码应该可以解决以下问题：

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>

其他资源

有关图形转换的更多信息，请参阅：

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

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