更改十字头发matplotlib光标示例的起始位置

Question

绘制时捕捉光标从(0,0(开始，使我的图形非常小。

它在做这个

而不是这个

我认为代码是这样做的，最初十字头发从(0,0(开始，但我不知道如何改变这一点。

Snapping Cursor的代码(此处链接(：

import numpy as np
import matplotlib.pyplot as plt
class SnappingCursor:
"""
A cross hair cursor that snaps to the data point of a line, which is
closest to the *x* position of the cursor.
For simplicity, this assumes that *x* values of the data are sorted.
"""
def __init__(self, ax, line):
self.ax = ax
self.horizontal_line = ax.axhline(color='k', lw=0.8, ls='--')
self.vertical_line = ax.axvline(color='k', lw=0.8, ls='--')
self.x, self.y = line.get_data()
self._last_index = None
# text location in axes coords
self.text = ax.text(0.72, 0.9, '', transform=ax.transAxes)
def set_cross_hair_visible(self, visible):
need_redraw = self.horizontal_line.get_visible() != visible
self.horizontal_line.set_visible(visible)
self.vertical_line.set_visible(visible)
self.text.set_visible(visible)
return need_redraw
def on_mouse_move(self, event):
if not event.inaxes:
self._last_index = None
need_redraw = self.set_cross_hair_visible(False)
if need_redraw:
self.ax.figure.canvas.draw()
else:
self.set_cross_hair_visible(True)
x, y = event.xdata, event.ydata
index = min(np.searchsorted(self.x, x), len(self.x) - 1)
if index == self._last_index:
return  # still on the same data point. Nothing to do.
self._last_index = index
x = self.x[index]
y = self.y[index]
# update the line positions
self.horizontal_line.set_ydata(y)
self.vertical_line.set_xdata(x)
self.text.set_text('x=%1.2f, y=%1.2f' % (x, y))
self.ax.figure.canvas.draw()

x = np.arange(0, 1, 0.01)
y = np.sin(2 * 2 * np.pi * x)
fig, ax = plt.subplots()
ax.set_title('Snapping cursor')
line, = ax.plot(x, y, 'o')
print(line)
snap_cursor = SnappingCursor(ax, line)
fig.canvas.mpl_connect('motion_notify_event', snap_cursor.on_mouse_move)
plt.show()

Answer 1

我认为您必须设置水平线的初始位置。__init__()应为：

def __init__(self, ax, line):
self.ax = ax
self.x, self.y = line.get_data()
self.horizontal_line = ax.axhline(y=self.y[0], xmin=self.x[0], xmax=self.x[-1], color='k', lw=0.8, ls='--')
self.vertical_line = ax.axvline(color='k', lw=0.8, ls='--')
self._last_index = None
# text location in axes coords
self.text = ax.text(0.72, 0.9, '', transform=ax.transAxes)

这对我很管用！

Answer 2

self.horizontal_line = ax.axhline(y=1000,color='k', lw=0.8, ls='--')
self.vertical_line = ax.axvline(x=2000, color='k', lw=0.8, ls='--')

使用"；y＝"；以及"；x＝"；或者在init函数中任意坐标。肯定行得通。