如何更改使用 host_subplot 创建的轴的标签（来自 AxesGrid 工具包）

Question

AxesGrid工具包提供了函数host_subplot，可以创建多个平行轴，如下代码所示：

from mpl_toolkits.axes_grid1 import host_subplot
import mpl_toolkits.axisartist as AA
import matplotlib.pyplot as plt


host = host_subplot(111, axes_class=AA.Axes)
plt.subplots_adjust(bottom=0.15)
par2 = host.twiny()
par2.axis["bottom"] = par2.get_grid_helper().new_fixed_axis(loc="bottom", axes=par2, offset=(0, -30) )
par2.axis["bottom"].toggle(all=True)

创建如下图：

现在我想更改添加在图像下方的第二个 x 轴的标签。我尝试了以下（除其他外）：

from mpl_toolkits.axes_grid1 import host_subplot
import mpl_toolkits.axisartist as AA
import matplotlib.pyplot as plt


host = host_subplot(111, axes_class=AA.Axes)
par2 = host.twiny()
par2.axis["bottom"] = par2.get_grid_helper().new_fixed_axis(loc="bottom", axes=par2, offset=(0, -30) )

for item in par2.get_xticklabels(): 
    item.set_text('new label')

par2.axis["bottom"].toggle(all=True)

遗憾的是 par2.get_xticklabels() 似乎没有像我天真地预期的那样工作（即它没有 return x 轴的标签）。

我发现解决类似问题的最相似问题是 How to change the font size for multiple axes labels (created with host_subplot API)，它会更改字体大小属性（不是附加到 xaxis 刻度的单个标签）。

Answer 1

好吧，我在尝试寻找答案时学到了一件事：IPython 是一个 非常好的 帮手.

总之，进入正题。通过 get_xticklabels() 对每个条目进行迭代来设置文本似乎存在一些问题。通过使用 set_text(my_text) 进行赋值，即使 my_text 确实传递了 Text 对象，但出于某种原因它之后没有拾取它。

例证：

[item.set_text("Some Text") for item in par2.get_xticklabels()]

for item in par2.get_xticklabels():
    print item

# Prints
Text(0,0,'Some Text')
Text(0,0,'Some Text')
Text(0,0,'Some Text')
Text(0,0,'Some Text')
Text(0,0,'Some Text')
Text(0,0,'Some Text')

# plt.show() does not display these changes.

谢天谢地（奇怪的是），设置标签 工作通过 set_xticklabels()

# Omitting rest of script.

# Set as False or else the top axis also gets these labels.
# Try commenting the line out to view what I mean.
par2.axis["top"].set_visible(False)
par2.set_xticklabels(["THIS", "IS", "PROBABLY", "A", "LITTLE", "BUG"])

plt.show()

本案例中绘制的图形就是您要查找的图形：

为了补充这是一个小错误的假设，与之前相同的 print 语句的输出 returns 与之前类似的表示形式。

for item in par2.get_xticklabels():
    print item

Text(0,0,'THIS')
Text(0,0,'IS')
Text(0,0,'PROBABLY')
Text(0,0,'A')
Text(0,0,'LITTLE')
Text(0,0,'BUG')

我不是 matplotlib 的最佳人选，但这看起来很可疑。也许有更多知识的人可以验证。

Answer 2

Dimitris 的回答太棒了！无论如何，我将在下面描述我完成使用的解决方法（在得到他的回答之前）。策略是在图形上添加一个新轴，然后隐藏除 x 轴之外的所有内容。此解决方案的唯一优点是不需要使用 AxesGrid 框架。

import matplotlib.pyplot as plt

def add_extra_xaxis(fig, x, labels, padding=35):
    """
    Add a x axis bellow the figure (indeed bellow the ax returned by fig.gca()) having the labels
    in the x positions. The axis is added by first adding an entire new axes and the hiding all
    parts, except the xaxis.

     Parameters
    ------------

    fig : Figure
        The figure where to add the xaxis.

    x : list
        List of numbers specifying the x positions.

    labels : list
        List of strings specifying the labels to place in the x positions.

    padding : int
        How much space should be added between the figure and the new x axis bellow it.

     Returns
    ---------

    new_ax : Axes
        Return the axes added to the image.

    """

    # Add some space bellow the figure
    fig.subplots_adjust(bottom=0.2)

    # Get current ax
    ax = fig.gca()

    # Add a new ax to the figure
    new_ax = fig.add_axes(ax.get_position())

    # Hide the the plot area and the yaxis
    new_ax.patch.set_visible(False)
    new_ax.yaxis.set_visible(False)

    # Hide spines (unless the boottom one)
    for spinename, spine in new_ax.spines.iteritems():
        if spinename != 'bottom':
            spine.set_visible(False)

    # Set the ....
    new_ax.spines['bottom'].set_position(('outward', padding))

    # Change tick labels
    plt.xticks([0] + x, [''] + labels) # the [0] and [''] stuff is to add an empty lable in the first position

    return new_ax


if __name__=='__main__':

    f, _ = plt.subplots()
    add_extra_xaxis(f, [1,3,5,7,10],['Now','it','should', 'work', ''], padding=30)

如何更改使用 host_subplot 创建的轴的标签（来自 AxesGrid 工具包）

How to change the labels of an axis created with host_subplot (from AxesGrid toolkit)

python

axes

matplotlib

multiple-axes