Basically, you're asking how to interactively select points in a rectangular region.
There's a matplotlib widget which will handle part of this (interactively drawing a rectangle) for you: matplotlib.widgets.RectangleSelector. You'll need to handle what you want to do with the rectangular region, though.
As a basic example, let's interactively highlight points inside a rectangle (this is an inefficient way to do that, but we'll need to build on this example to do what you want). After the figure window is closed, this will print out the points not selected (~ operates as logical_not on numpy arrays):
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import RectangleSelector
def main():
x, y = np.random.random((2, 100))
fig, ax = plt.subplots()
ax.scatter(x, y, color='black')
highlighter = Highlighter(ax, x, y)
plt.show()
selected_regions = highlighter.mask
# Print the points _not_ selected
print x[~selected_regions], y[~selected_regions]
class Highlighter(object):
def __init__(self, ax, x, y):
self.ax = ax
self.canvas = ax.figure.canvas
self.x, self.y = x, y
self.mask = np.zeros(x.shape, dtype=bool)
self._highlight = ax.scatter([], [], s=200, color='yellow', zorder=10)
self.selector = RectangleSelector(ax, self, useblit=True)
def __call__(self, event1, event2):
self.mask |= self.inside(event1, event2)
xy = np.column_stack([self.x[self.mask], self.y[self.mask]])
self._highlight.set_offsets(xy)
self.canvas.draw()
def inside(self, event1, event2):
"""Returns a boolean mask of the points inside the rectangle defined by
event1 and event2."""
# Note: Could use points_inside_poly, as well
x0, x1 = sorted([event1.xdata, event2.xdata])
y0, y1 = sorted([event1.ydata, event2.ydata])
mask = ((self.x > x0) & (self.x < x1) &
(self.y > y0) & (self.y < y1))
return mask
main()
However, you have an additional wrinkle, as you have two linked plots. You want a selection on the X-Y plot to also select things on the X-Z plot. Let's modify things to handle that:
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import RectangleSelector
def main():
x, y, z = np.random.random((3, 100))
z *= 10
fig, axes = plt.subplots(figsize=(6, 8), nrows=2, sharex=True)
axes[0].scatter(x, y, color='black')
axes[1].scatter(x, z, color='black')
axes[0].set(ylabel='Y')
axes[1].set(xlabel='X', ylabel='Y')
highlighter = Highlighter(axes, x, y, z)
plt.show()
selected_regions = highlighter.mask
print x[~selected_regions], y[~selected_regions], z[~selected_regions]
class Highlighter(object):
def __init__(self, axes, x, y, z):
self.axes = axes
self.canvas = axes[0].figure.canvas
self.x, self.y, self.z = x, y, z
self.mask = np.zeros(x.shape, dtype=bool)
self._highlights = [ax.scatter([], [], s=200, color='yellow', zorder=10)
for ax in axes]
self._select1 = RectangleSelector(axes[0], self.select_xy, useblit=True)
self._select2 = RectangleSelector(axes[1], self.select_xz, useblit=True)
def select_xy(self, event1, event2):
self.mask |= self.inside(event1, event2, self.x, self.y)
self.update()
def select_xz(self, event1, event2):
self.mask |= self.inside(event1, event2, self.x, self.z)
self.update()
def update(self):
xy = np.column_stack([self.x[self.mask], self.y[self.mask]])
self._highlights[0].set_offsets(xy)
xz = np.column_stack([self.x[self.mask], self.z[self.mask]])
self._highlights[1].set_offsets(xz)
self.canvas.draw()
def inside(self, event1, event2, x, y):
x0, x1 = sorted([event1.xdata, event2.xdata])
y0, y1 = sorted([event1.ydata, event2.ydata])
return (x > x0) & (x < x1) & (y > y0) & (y < y1)
main()
