set_aspect('equal')的行为不像预期的那样

I need a figure in matplotlib where both axes are always the same length. For this I am using the option 'equal'. In most cases it works quite well and I get the expected results (see figure 1), but when the values of the y-axis are much higher than x, the figure shows an unexpected behaviour (see figure 2). Does anyone know this behavior of matplotlib?I need a figure in matplotlib where both axes a