使用matplotlib，如何打印“实际尺寸"? [英] Using matplotlib, how can I print something "actual size"?

问题描述

我有很多图，其中x轴和y轴以厘米为单位，并且我已经在使用axis('equal')来确保适当的宽高比.我想打印出这些图，以便当我测量轴上的距离时，该距离对应于现实世界中的厘米.

I have a number of plots where the x- and y-axes are in centimeter units, and I am already using axis('equal') to ensure proper aspect ratios. I would like to print out those plots so that when I measure distances within my axes, the distances correspond to real-world centimeters.

也就是说，在图中长3单位(厘米)的线应打印为3厘米长. (一个更复杂的示例是在Matplotlib中绘制标尺，然后将其打印出来以供/as/标尺使用.)我在matlab和mathematica中找到了解决方案，但没有找到Matplotlib.有一个神奇的公式可以实现这一目标吗?我相信它将需要以下各项的特殊组合/排序:f igure(figsize=??), axis('equal')，fig.canvas.draw()，fig.savefig('filename',format="??")，可能带有fig.bbox参数的一些数学运算以及一个或多个dpi设置.我尝试了许多组合，但没有找到正确的组合.也许有一种更简便的方法...

That is, a line that is 3 units (cm) long in the plot should print out to be 3 cm long. (A more complex example would be drawing a ruler in Matplotlib, and then printing it out for use /as/ a ruler.) I found solutions in matlab and mathematica, but not for Matplotlib. Is there a magic formula to achieve this? I believe it will require a special combination/ordering of: figure(figsize=??), axis('equal'), fig.canvas.draw(), fig.savefig('filename',format="??"), possibly some math with fig.bbox parameters, and perhaps one or more dpi-settings. I have tried many combinations but haven't hit on the right one. And maybe there is a way-easier approach ...

推荐答案

将其添加到@pablo reyes的答案中，检查打印机是否为100％，并且非常接近；

Add this to @pablo reyes' answer, check that the printer is at 100%, and it's pretty close;

ax.set_ylim(0,7)
ax.set_xlim(0,10)

ax.plot([0.5, 1.5],[0.25, 0.25],label='One cm?')
ax.plot([6,6],[1,2], label='One cm?')
ax.legend()

我们强制轴成为我们知道的尺寸，使它的数据转换与现实世界匹配，然后我们可以打印尺子".

we force the axis to be a size we know, we make its data-transform match the real world, and we can "print a ruler".

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