在轮廓上绘制点-Matplotlib / Python

我正在尝试使用Matplotlib在轮廓上绘制一些点。

我有要从中绘制轮廓的标量场。但是，我的ndarray的尺寸为0 x 20，但是我的实际空间从-4到4不等。

我可以使用以下代码绘制此轮廓：

x, y = numpy.mgrid[-4:4:20*1j, -4:4:20*1j]

# Draw the scalar field level curves
cs = plt.contour(scalar_field, extent=[-4, 4, -4, 4])
plt.clabel(cs, inline=1, fontsize=10)

问题在于，因为我必须在该图上绘制一些点，并且这些点是使用ndarray获得的，即，我得到的点随此数组维数而变化。

我试图使用以下代码绘制这些点：

def plot_singularities(x_dim, y_dim, steps, scalar_field, min_points, max_points, file_path):
    """
    :param x_dim : the x dimension of the scalar field
    :param y_dim : the y dimension of the scalar field
    :param steps : the discretization of the scalar field
    :param file_path : the path to save the data
    :param scalar_field : the scalar_field to be plot
    :param min_points : a set (x, y) of min points of the scalar field
    :param max_points : a set (x, y) of max points of the scalar field
    """
    min_points_x = min_points[0]
    min_points_y = min_points[1]
    max_points_x = max_points[0]
    max_points_y = max_points[1]

    plt.figure()

    x, y = numpy.mgrid[-x_dim:x_dim:steps*1j, -y_dim:y_dim:steps*1j]

    # Draw the scalar field level curves
    cs = plt.contour(scalar_field, extent=[-x_dim, x_dim, -y_dim, y_dim])
    plt.clabel(cs, inline=1, fontsize=10)

    # Draw the min points
    plt.plot(min_points_x, min_points_y, 'ro')

    # Draw the max points
    plt.plot(max_points_x, max_points_y, 'bo')

    plt.savefig(file_path + '.png', dpi=100)
    plt.close()

但是我得到了这张图片：

这是不正确的。

如果我更改此行：

cs = plt.contour(scalar_field, extent=[-x_dim, x_dim, -y_dim, y_dim])

对于那个：

cs = plt.contour(scalar_field)

I get the desired behavior, but the extents doesn't show my real data space, but the ndarray dimension.

At last, if I don't plot these points (comment the plot() lines), I can the extents that I want:

But I have to plot the points. Both data are in the same space. But the contour() function allows me to specify the grid. I could found a manner to do this when plotting the points.

How can I properly set the extents?