等高线图演示 显示了如何绘制曲线并在其上绘制级别值，如下所示:
是否有一种方法可以将下面代码生成的简单线性图形式转换为类似的效果?
import matplotlib.pyplot as plt
x = [1.81,1.715,1.78,1.613,1.629,1.714,1.62,1.738,1.495,1.669,1.57,1.877,1.385]
y = [0.924,0.915,0.914,0.91,0.909,0.905,0.905,0.893,0.886,0.881,0.873,0.873,0.844]
# This is the string that should show somewhere over the plotted line.
line_string = 'name of line'
# plotting
plt.plot(x,y)
plt.show()
import matplotlib.pyplot as plt
import numpy as np
x = [1.81,1.715,1.78,1.613,1.629,1.714,1.62,1.738,1.495,1.669,1.57,1.877,1.385]
y = [0.924,0.915,0.914,0.91,0.909,0.905,0.905,0.893,0.886,0.881,0.873,0.873,0.844]
# This is the string that should show somewhere over the plotted line.
line_string = 'name of line'
# plotting
fig, ax = plt.subplots(1,1)
l, = ax.plot(x,y)
pos = [(x[-2]+x[-1])/2., (y[-2]+y[-1])/2.]
# transform data points to screen space
xscreen = ax.transData.transform(zip(x[-2::],y[-2::]))
rot = np.rad2deg(np.arctan2(*np.abs(np.gradient(xscreen)[0][0][::-1])))
ltex = plt.text(pos[0], pos[1], line_string, size=9, rotation=rot, color = l.get_color(),
ha="center", va="center",bbox = dict(ec='1',fc='1'))
def updaterot(event):
"""Event to update the rotation of the labels"""
xs = ax.transData.transform(zip(x[-2::],y[-2::]))
rot = np.rad2deg(np.arctan2(*np.abs(np.gradient(xs)[0][0][::-1])))
ltex.set_rotation(rot)
fig.canvas.mpl_connect('button_release_event', updaterot)
plt.show()
这样做可以让您拥有最大的控制权。
请注意，旋转以度为单位，在屏幕空间中而不是数据空间中。
由于我最近需要自动标签旋转，需要在缩放和平移时更新，因此我更新了我的答案以满足这些需求。现在，标签旋转在每次鼠标按钮释放时更新（仅使用draw_event当缩放时不会触发）。 此方法使用matplotlib转换将数据空间和屏幕空间链接起来，如本教程所述。
zip（x[-2::],y[-2::]）替换为np.array((x[-2::],y[-2::]))才能使变换调用起作用。 - nedlrichards基于Jakob的代码，这里提供了一个在数据空间中旋转文本、在给定x或y数据坐标附近放置标签，并且也适用于对数图的函数。
def label_line(line, label_text, near_i=None, near_x=None, near_y=None, rotation_offset=0, offset=(0,0)):
"""call
l, = plt.loglog(x, y)
label_line(l, "text", near_x=0.32)
"""
def put_label(i):
"""put label at given index"""
i = min(i, len(x)-2)
dx = sx[i+1] - sx[i]
dy = sy[i+1] - sy[i]
rotation = np.rad2deg(math.atan2(dy, dx)) + rotation_offset
pos = [(x[i] + x[i+1])/2. + offset[0], (y[i] + y[i+1])/2 + offset[1]]
plt.text(pos[0], pos[1], label_text, size=9, rotation=rotation, color = line.get_color(),
ha="center", va="center", bbox = dict(ec='1',fc='1'))
x = line.get_xdata()
y = line.get_ydata()
ax = line.get_axes()
if ax.get_xscale() == 'log':
sx = np.log10(x) # screen space
else:
sx = x
if ax.get_yscale() == 'log':
sy = np.log10(y)
else:
sy = y
# find index
if near_i is not None:
i = near_i
if i < 0: # sanitize negative i
i = len(x) + i
put_label(i)
elif near_x is not None:
for i in range(len(x)-2):
if (x[i] < near_x and x[i+1] >= near_x) or (x[i+1] < near_x and x[i] >= near_x):
put_label(i)
elif near_y is not None:
for i in range(len(y)-2):
if (y[i] < near_y and y[i+1] >= near_y) or (y[i+1] < near_y and y[i] >= near_y):
put_label(i)
else:
raise ValueError("Need one of near_i, near_x, near_y")