自动在matplotlib中定位文本框

Question

有没有办法告诉pyplot.text()像pyplot.legend()一样的位置？

像传奇论点这样的东西会很棒:

plt.legend(loc="upper left")

我试图用字母标记不同轴的子图(例如"A","B").我认为必须有一种比手动估算位置更好的方法.

谢谢

Answer 1

只需使用annotate并指定轴坐标即可.例如,"左上角"将是:

plt.annotate('Something', xy=(0.05, 0.95), xycoords='axes fraction')

你也可以变得更漂亮,并指定一个点的常量偏移:

plt.annotate('Something', xy=(0, 1), xytext=(12, -12), va='top'
             xycoords='axes fraction', textcoords='offset points')

更多解释见例子在这里和更详细的例子在这里.

Answer 2

我最初发布问题时不确定这是否可用,但现在可以使用loc参数.以下是一个例子:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.offsetbox import AnchoredText

# make some data
x = np.arange(10)
y = x

# set up figure and axes
f, ax = plt.subplots(1,1)

# loc works the same as it does with figures (though best doesn't work)
# pad=5 will increase the size of padding between the border and text
# borderpad=5 will increase the distance between the border and the axes
# frameon=False will remove the box around the text

anchored_text = AnchoredText("Test", loc=2)
ax.plot(x,y)
ax.add_artist(anchored_text)

plt.show()

Answer 3

这个问题已经很老了，但由于根据Add loc=best kwarg to pyplot.text()直到现在（2019 年）还没有通用的解决方案，我正在使用legend()以下解决方法来获得简单文本的自动放置盒子：

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mpl_patches

x = np.linspace(-1,1)
fig, ax = plt.subplots()
ax.plot(x, x*x)

# create a list with two empty handles (or more if needed)
handles = [mpl_patches.Rectangle((0, 0), 1, 1, fc="white", ec="white", 
                                 lw=0, alpha=0)] * 2

# create the corresponding number of labels (= the text you want to display)
labels = []
labels.append("pi = {0:.4g}".format(np.pi))
labels.append("root(2) = {0:.4g}".format(np.sqrt(2)))

# create the legend, supressing the blank space of the empty line symbol and the
# padding between symbol and label by setting handlelenght and handletextpad
ax.legend(handles, labels, loc='best', fontsize='small', 
          fancybox=True, framealpha=0.7, 
          handlelength=0, handletextpad=0)
plt.show()

一般的想法是创建一个带有空行符号的图例，然后删除由此产生的空白空间。如何调整matplotlib图例框的大小？帮助我处理图例格式。