如何将Figure对象转换为具有RGBA值的Numpy数组？

Question

我有Plotly Figure对象，我曾经使用Plotly创建图形。我想将此Figure对象转换为Numpy Array。这样我就可以将该数组数据转换为PIL Image对象。然后使用.drawImage方法在Reportlab上绘制drawImage。

这里，b是情节图对象。

def fig2data ( b ):
    """
    @brief Convert a Matplotlib figure to a 4D numpy array with RGBA channels and return it
    @param fig a matplotlib figure
    @return a numpy 3D array of RGBA values
    """
    # draw the renderer
    fig.canvas.draw ( )
    # Get the RGBA buffer from the figure
    w,h = fig.canvas.get_width_height()
    buf = numpy.fromstring ( fig.canvas.tostring_argb(), dtype=numpy.uint8 )
    buf.shape = ( w, h,4 )
    # canvas.tostring_argb give pixmap in ARGB mode. Roll the ALPHA channel to have it in RGBA mode
    buf = numpy.roll ( buf, 3, axis = 2 )
    return buf

buf = fig2data(b)
buf

这给了我

AttributeError: 'Figure' object has no attribute 'canvas'

谢谢。

Answer 1

    from matplotlib.backends.backend_agg import FigureCanvasAgg

    def fig2data ( b ):
        """
        @brief Convert a Matplotlib figure to a 4D numpy array with RGBA channels 
         and return it
        @param fig a matplotlib figure
        @return a numpy 3D array of RGBA values
        """

        canvas = FigureCanvasAgg(fig)
        # draw the renderer
        fig.canvas.draw ( )
        # Get the RGBA buffer from the figure
        w,h = fig.canvas.get_width_height()
        buf = numpy.fromstring ( fig.canvas.tostring_argb(), dtype=numpy.uint8 )
        buf.shape = ( w, h,4 )
        # canvas.tostring_argb give pixmap in ARGB mode. Roll the ALPHA channel to 
         have it in RGBA mode
        buf = numpy.roll ( buf, 3, axis = 2 )
        return buf

    buf = fig2data(b)
    buf

希望这会有所帮助