8

如何注释我的数据范围？例如，假设从x = 5to的数据x = 10大于某个截止值，我怎么能在图表上指出这一点。如果我是手动注释，我会在范围上方画一个大括号，然后在括号上方写下我的注释。

我见过的最接近的是使用arrowstyle='<->'andconnectionstyle='bar'来制作两个指向数据边缘的箭头，并用一条线连接它们的尾部。但这并不完全正确。您为注释输入的文本最终会出现在箭头之一的下方，而不是栏的上方。

这是我的尝试及其结果：

annotate(' ', xy=(1,.5),  xycoords='data',
            xytext=(190, .5), textcoords='data',
            arrowprops=dict(arrowstyle="<->",
                            connectionstyle="bar",
                            ec="k",
                            shrinkA=5, shrinkB=5,
                            )
            )

注释尝试

我尝试的解决方案的另一个问题是注释括号的方形并没有真正清楚地表明我正在突出显示一个范围（与例如花括号不同）。但我想这只是在这一点上吹毛求疵。

4

4 回答 4

8

如this answer中所述，您可以使用 sigmoidal 函数构造大括号。下面是一个在 x 轴上方添加大括号的函数。只要图形宽度和高度不变，它产生的花括号应该看起来相同，无论轴限制如何。

import numpy as np
import matplotlib.pyplot as plt

def draw_brace(ax, xspan, text):
    """Draws an annotated brace on the axes."""
    xmin, xmax = xspan
    xspan = xmax - xmin
    ax_xmin, ax_xmax = ax.get_xlim()
    xax_span = ax_xmax - ax_xmin
    ymin, ymax = ax.get_ylim()
    yspan = ymax - ymin
    resolution = int(xspan/xax_span*100)*2+1 # guaranteed uneven
    beta = 300./xax_span # the higher this is, the smaller the radius

    x = np.linspace(xmin, xmax, resolution)
    x_half = x[:resolution//2+1]
    y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
                    + 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
    y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
    y = ymin + (.05*y - .01)*yspan # adjust vertical position

    ax.autoscale(False)
    ax.plot(x, y, color='black', lw=1)

    ax.text((xmax+xmin)/2., ymin+.07*yspan, text, ha='center', va='bottom')

ax = plt.gca()
ax.plot(range(10))
draw_brace(ax, (0, 8), 'large brace')
draw_brace(ax, (8, 9), 'small brace')

输出：

在此处输入图像描述

于 2018-11-19T22:48:42.280 回答
5

我修改了 Joooeey 的答案以允许更改大括号的垂直位置：

def draw_brace(ax, xspan, yy, text):
    """Draws an annotated brace on the axes."""
    xmin, xmax = xspan
    xspan = xmax - xmin
    ax_xmin, ax_xmax = ax.get_xlim()
    xax_span = ax_xmax - ax_xmin

    ymin, ymax = ax.get_ylim()
    yspan = ymax - ymin
    resolution = int(xspan/xax_span*100)*2+1 # guaranteed uneven
    beta = 300./xax_span # the higher this is, the smaller the radius

    x = np.linspace(xmin, xmax, resolution)
    x_half = x[:int(resolution/2)+1]
    y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
                    + 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
    y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
    y = yy + (.05*y - .01)*yspan # adjust vertical position

    ax.autoscale(False)
    ax.plot(x, y, color='black', lw=1)

    ax.text((xmax+xmin)/2., yy+.07*yspan, text, ha='center', va='bottom')

ax = plt.gca()
ax.plot(range(10))
draw_brace(ax, (0, 8), -0.5, 'large brace')
draw_brace(ax, (8, 9), 3, 'small brace')

输出：

matplotlib 大括号

另请注意，在Joooeey 的回答中，行

x_half = x[:resolution/2+1]

应该

x_half = x[:int(resolution/2)+1]

否则，脚本在这里尝试用作索引的数字是浮点数。

最后，请注意，如果您将其移出边界，则现在大括号将不会显示。您需要添加参数clip_on=False，如下所示：

ax.plot(x, y, color='black', lw=1, clip_on=False)
于 2020-04-27T08:18:03.480 回答
4

您可以将其全部包装在一个函数中：

def add_range_annotation(ax, start, end, txt_str, y_height=.5, txt_kwargs=None, arrow_kwargs=None):
    """
    Adds horizontal arrow annotation with text in the middle

    Parameters
    ----------
    ax : matplotlib.Axes
        The axes to draw to

    start : float
        start of line

    end : float
        end of line

    txt_str : string
        The text to add

    y_height : float
        The height of the line

    txt_kwargs : dict or None
        Extra kwargs to pass to the text

    arrow_kwargs : dict or None
        Extra kwargs to pass to the annotate

    Returns
    -------
    tuple
        (annotation, text)
    """

    if txt_kwargs is None:
        txt_kwargs = {}
    if arrow_kwargs is None:
        # default to your arrowprops
        arrow_kwargs = {'arrowprops':dict(arrowstyle="<->",
                            connectionstyle="bar",
                            ec="k",
                            shrinkA=5, shrinkB=5,
                            )}

    trans = ax.get_xaxis_transform()

    ann = ax.annotate('', xy=(start, y_height),
                        xytext=(end, y_height),
                        transform=trans,
                        **arrow_kwargs)
    txt = ax.text((start + end) / 2,
                  y_height + .05,
                  txt_str,
                  **txt_kwargs)


    if plt.isinteractive():
        plt.draw()
    return ann, txt

交替，

start, end = .6, .8
ax.axvspan(start, end, alpha=.2, color='r')
trans = ax.get_xaxis_transform()
ax.text((start + end) / 2, .5, 'test', transform=trans)
于 2013-08-22T17:07:47.250 回答
1

这是对guzey和jooeey将花括号绘制在轴外的答案的一个小修改。

def draw_brace(ax, xspan, yy, text):
"""Draws an annotated brace outside the axes."""
    xmin, xmax = xspan
    xspan = xmax - xmin
    ax_xmin, ax_xmax = ax.get_xlim()
    xax_span = ax_xmax - ax_xmin

    ymin, ymax = ax.get_ylim()
    yspan = ymax - ymin
    resolution = int(xspan/xax_span*100)*2+1 # guaranteed uneven
    beta = 300./xax_span # the higher this is, the smaller the radius

    x = np.linspace(xmin, xmax, resolution)
    x_half = x[:int(resolution/2)+1]
    y_half_brace = (1/(1.+np.exp(-beta*(x_half-x_half[0])))
                + 1/(1.+np.exp(-beta*(x_half-x_half[-1]))))
    y = np.concatenate((y_half_brace, y_half_brace[-2::-1]))
    y = yy + (.05*y - .01)*yspan # adjust vertical position

    ax.autoscale(False)
    ax.plot(x, -y, color='black', lw=1, clip_on=False)

    ax.text((xmax+xmin)/2., -yy-.17*yspan, text, ha='center', va='bottom')

    
# Sample code
fmax = 1
fstart = -100
fend = 0
frise = 50
ffall = 20

def S(x):
   if x<=0:
       return 0
   elif x>=1:
       return 1
   else:
       return 1/(1+np.exp((1/(x-1))+(1/x)))

x = np.linspace(700,1000,500)
lam = [fmax*(S((i-880)/60)-S(((i-1000)/25)+1)) for i in x]
fig = plt.figure(1)
ax = fig.add_subplot(111)
plt.plot(x,lam)
plt.xlim([850,1000])
ax.set_aspect(50,adjustable='box')
plt.ylabel('$\lambda$')
plt.xlabel('$x$')
ax.xaxis.set_label_coords(0.5, -0.35)
draw_brace(ax, (900,950),0.2, 'rise')
draw_brace(ax, (980,1000),0.2, 'fall')
plt.text(822,0.95,'$(\lambda_{\mathrm{max}})$')

样本输出

于 2021-06-29T14:38:06.910 回答