插入轴的特定位置 [英] specific location for inset axes

问题描述

我想创建一组轴以在父轴组中的特定位置形成一个插入。因此，在 inset_axes 中使用参数 loc = 1,2,3 是不合适的，如下所示：

  inset_axes = inset_axes（parent_axes，
 width =30％，＃width = 30％parent_bbox 
 height = 1。，＃height：1 inch 
 loc = 3）
  

然而， ，我想要接近这个。和答案这里和这里似乎是比我的问题稍微复杂的问题的答案。

所以问题是，在上面的代码中是否可以替换一个参数，以允许父轴内嵌入轴的自定义位置？我试过使用 bbox_to_anchor ，但不明白它的规范或行为来自文档。具体来说，我试过：

  inset_axes = inset_axes（parent_axes，
 width =30％，＃width = 30％的parent_bbox 
 height = 1。，＃height：1 inch 
 bbox_to_anchor =（0.4,0.1））
  

尝试使插入点的左侧和底部的锚点分别为x和y轴的40％和10％。或者，我试图把它放在绝对坐标中：

pre $ inset_axes（parent_axes，
width =30％ ，＃width = 30％parent_bbox
height = 1。，＃height：1 inch
bbox_to_anchor =（ - 4，-100））

这些工作都不正确，并给了我一个我无法解释的警告。

更一般地说，好像 loc 是属于 matplotlib ，那么，是否有一个通用的解决方案可以在任何地方使用？看起来这就是 bbox_to_anchor ，但是我再次无法弄清楚如何正确使用它。

解决方案

您采取的方法原则上是正确的。然而，就像放置图例与 bbox_to_anchor 一样，位置被确定为 bbox_to_anchor 和 loc 之间的相互作用。上面链接答案中的大部分解释也适用于此处。

loc /inset_locator_api.html#mpl_toolkits.axes_grid1.inset_locator.inset_axesrel =nofollow noreferrer> inset_axes 是 loc = 1 （右上角）。这意味着如果你指定 bbox_to_anchor =（0.4,0.1），那些将是右上角的坐标，而不是左下角的坐标。

因此，您需要指定 loc = 3 以使插入点的左下角位于（0.4,0.1）。但是，如果没有以相对单位指定宽度和高度（30％），则指定边界为2元组是合理的。 / code>）。换句话说，为了使用相对单位，您需要为 bbox_to_anchor 使用四元组符号。

如果在轴单位中指定 bbox_to_anchor ，则需要再次使用 bbox_transform 参数，就像传说解释此处，并将其设置为 ax.transAxes 。

  plt.figure（figsize =（6,3））
 ax = plt.subplot（221）
 ax.set_title（100％，（0.5,1-0.3，.3，.3））
 ax.plot（xdata，ydata）
 axins = inset_axes（ax，width =100 ％，height =100％，loc ='左上角'，
 bbox_to_anchor =（0.5,1-0.3，.3，.3），bbox_transform = ax.transAxes）
 
 
 ax = plt.subplot（222）
 ax.set_title（30％，（0.5,0,1,1））
 ax.plot（xdata，ydata）
 axins = inset_axes（ax，width =30％，height =30％，loc ='左上角'，
 bbox_to_anchor =（0.5,0,1,1），bbox_transform = ax.transAxes ）
  

< img src =https://i.stack.imgur.com/TCvc0.pngalt =在这里输入图片描述>

但是，文档错误或者当前matplotlib版本中存在一些错误 ，因此上述内容不起作用。 （这是一个文档问题，应该很快修复 ）。

另一个选项是使用 InsetPosition 而不是 inset_axes 并给现有轴一个新的位置。 InsetPosition 以规范化坐标轴的坐标轴的左下角的x和y坐标，以及宽度和高度作为输入。

  import matplotlib.pyplot as plt 
 from mpl_toolkits.axes_grid1.inset_locator import InsetPosition 
 
 fig，ax = plt.subplots （），
 
 iax = plt.axes（[0,0,1,1]）$ ​​b $ b ip = InsetPosition（ax，[0.4,0.1,0.3,0.7]）#posx，posy ，宽度，高度
 iax.set_axes_locator（ip）
 
 iax.plot（[1,2,4]）
 plt.show（）
  

I want to create a set of axes to form an inset at a specific location in the parent set of axes. It is therefore not appropriate to just use the parameter loc=1,2,3 in the inset_axes as shown here:

inset_axes = inset_axes(parent_axes,
                    width="30%", # width = 30% of parent_bbox
                    height=1., # height : 1 inch
                    loc=3)

However, I would like something close to this. And the answers here and here seem to be answers to questions slightly more complicated than mine.

So, the question is is there a parameter that I can replace in the above code that will allow custom locations of the inset axes within the parent axes? I've tried to use the bbox_to_anchor but do not understand it's specification or behavior from the documentation. Specifically I've tried:

 inset_axes = inset_axes(parent_axes,
                        width="30%", # width = 30% of parent_bbox
                        height=1., # height : 1 inch
                        bbox_to_anchor=(0.4,0.1))

to try to get the anchor for the left and bottom of the inset to be at 40% and 10% of the x and y axis respectively. Or, I tried to put it in absolute coordinates:

inset_axes = inset_axes(parent_axes,
                            width="30%", # width = 30% of parent_bbox
                            height=1., # height : 1 inch
                            bbox_to_anchor=(-4,-100))

Neither of these worked correctly and gave me a warning that I couldn't interpret.

More generally, it seems like loc is a pretty standard parameter in many functions belonging to matplotlib, so, is there a general solution to this problem that can be used anywhere? It seems like that's what bbox_to_anchor is but again, I can't figure out how to use it correctly.

解决方案

The approach you took is in principle correct. However, just like when placing a legend with bbox_to_anchor, the location is determined as an interplay between bbox_to_anchor and loc. Most of the explanation in the above linked answer applies here as well.

The default loc for inset_axes is loc=1 ("upper right"). This means that if you you specify bbox_to_anchor=(0.4,0.1), those will be the coordinates of the upper right corner, not the lower left one.
You would therefore need to specify loc=3 to have the lower left corner of the inset positionned at (0.4,0.1).

However, specifying a bounding as a 2-tuple only makes sense if not specifying the width and height in relative units ("30%"). Or in other words, in order to use relative units you need to use a 4-tuple notation for the bbox_to_anchor.

In case of specifying the bbox_to_anchor in axes units one needs to use the bbox_transform argument, again, just as with legends explained here, and set it to ax.transAxes.

plt.figure(figsize=(6,3))
ax = plt.subplot(221)
ax.set_title("100%, (0.5,1-0.3,.3,.3)")
ax.plot(xdata, ydata)
axins = inset_axes(ax, width="100%", height="100%", loc='upper left',
                   bbox_to_anchor=(0.5,1-0.3,.3,.3), bbox_transform=ax.transAxes)


ax = plt.subplot(222)
ax.set_title("30%, (0.5,0,1,1)")
ax.plot(xdata, ydata)
axins = inset_axes(ax, width="30%", height="30%", loc='upper left',
                   bbox_to_anchor=(0.5,0,1,1), bbox_transform=ax.transAxes)

However, either the documentation is wrong or there is some bug in the current matplotlib version, such that the above will not work. (This was a documentation issue, which should soon be fixed.)

Another option is to use InsetPosition instead of inset_axes and to give an existing axes a new position. InsetPosition takes the x and y coordinates of the lower left corner of the axes in normalized axes coordinates, as well as the width and height as input.

import matplotlib.pyplot as plt
from mpl_toolkits.axes_grid1.inset_locator import InsetPosition

fig, ax= plt.subplots()

iax = plt.axes([0, 0, 1, 1])
ip = InsetPosition(ax, [0.4, 0.1, 0.3, 0.7]) #posx, posy, width, height
iax.set_axes_locator(ip)

iax.plot([1,2,4])
plt.show()

这篇关于插入轴的特定位置的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！