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@EugeneLoy
Last active Nov 15, 2016
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What would you like to do?
pyplot: draw a line through 1 or 2 reference points (works with scrolling)
import matplotlib.pyplot as plt
def axline(xdata, ydata, ax = plt.subplot(111), *args, **kwargs):
try:
x1 = xdata[0]
y1 = ydata[0]
except:
# assume first point coordinates given as numbers
x1 = float(xdata)
y1 = float(ydata)
try:
x2 = xdata[1]
y2 = ydata[1]
except:
# assume no second point given - line passes (0, 0)
x2 = 0.
y2 = 0.
dx = float(x1 - x2)
dy = float(y1 - y2)
if dx == 0. and dy == 0.:
pass
elif dx == 0.:
ax.axvline(y1, *args, **kwargs)
elif dy == 0.:
ax.axhline(x1, *args, **kwargs)
else:
slope = dy / dx
intercept = y1 - slope * x1
def calculate_points():
(x1, x2) = ax.get_xlim()
return [x1, x2], [slope * x1 + intercept, slope * x2 + intercept]
line, = ax.plot(*(calculate_points() + args), **kwargs)
def on_change(axes):
line.set_data(*calculate_points())
ax.callbacks.connect('xlim_changed', on_change)
ax.callbacks.connect('ylim_changed', on_change)
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