OK, I think you want the equivalent of matlab?s
plot(something)
x,y = ginput(?Click the figure?)
plot(x, y)
*and* you want it to execute in an interactive session in `ipython`
(spyder)
I don?t think you can do that, though there may be some new widgets
that will let it happen these days.
Historically, it is better to think of any graphical interaction as a
separate program. If you are willing to do that, then plotting the
data as you click is very simple:
import matplotlib
matplotlib.use('Qt5Agg')
import matplotlib.pyplot as plt
import numpy as np
class Picker(object):
def __init__(self, ax=None):
self.x = np.array([])
self.y = np.array([])
self.ax = ax
self.dots, = ax.plot(1, 1, marker='o')
self.dots.set_xdata(self.x)
self.dots.set_ydata(self.y)
self.fig = self.ax.get_figure()
def process_key(self, event):
print("Key:", event.key)
def process_button(self, event):
print("Button:", event.x, event.y, event.xdata, event.ydata,
event.button)
self.x = np.append(self.x, event.xdata)
self.y = np.append(self.y, event.ydata)
self.dots.set_xdata(self.x)
self.dots.set_ydata(self.y)
plt.draw()
def get_x(self):
return self.x
def get_y(self):
return self.y
fig, ax = plt.subplots(1, 1)
picker = Picker(ax=ax)
fig.canvas.mpl_connect('key_press_event', picker.process_key)
fig.canvas.mpl_connect('button_press_event', picker.process_button)
plt.show()
print(picker.x) #
print(picker.get_x()) # the same
print(picker.get_x().mean()) # returns the mean of x.
print(picker.get_y())
print(picker.get_y().mean())
You save the above as a file (`mypicker.py`) and in `ipython` you
execute `run mypicker.py`. Note that after you have executed it,
`picker` is still in your workspace to access.
I hope that helps.
Jody
···
On 5 Sep 2017, at 6:33, Jean-Philippe Grivet wrote:
Thank you Benjamin and Jody for your sugestions. Due to my scanty
knwledge of Python,
I unfortunately can't get these programs to do what I want.
Referring to Jody's code, the statement "print(x)" is executed only
once, upon
lauching the program. Then, the various xdata values are stored in x
but nothing more
happens, until I close the graphic window. This termintes execution.
If I issue print(x)
in the console, I recover the values of interest. My attempts to plot
a dot where the
button was clicked have failed.
Ben's code behaves similarly, except that it starts by attempting to
compute the
average of some undefined values.
Can this poor performance be due to the fact that I work inside Spyder
?
I am sorry that I keep trying your patience but I will be grateful for
any
suggestion.
Sincetrely,
Jean-Philippe
>import matplotlib matplotlib.use('Qt5Agg') import matplotlib.pyplot
as plt import numpy as np class Picker(object): def __init__(self):
self.x = np.array([]) self.y = np.array([]) def process_key(self,
event): print("Key:", event.key) def process_button(self, event):
print("Button:", event.x, event.y, event.xdata, event.ydata,
event.button) self.x = np.append(self.x, event.xdata) self.y =
np.append(self.y, event.ydata) def get_x(self): return self.x def
get_y(self): return self.y fig, ax = plt.subplots(1, 1) picker =
Picker() fig.canvas.mpl_connect('key_press_event',
picker.process_key) fig.canvas.mpl_connect('button_press_event',
picker.process_button) plt.show() print(picker.x) #
print(picker.get_x()) # the same print(picker.get_x().mean()) #
returns the mean of x. print(picker.get_y())
print(picker.get_y().mean()) |
On 2 Sep 2017, at 18:08, Benjamin Root wrote:
If you assign a class method as the callbacks, such as
process_button(self, event), then that method could save the
relevant values to itself. I show how to do this in my book (as
well as the global approach, too).
Cheers!
Ben Root
On Sat, Sep 2, 2017 at 10:30 AM, Jody Klymak <jklymak at uvic.ca >> <mailto:jklymak at uvic.ca>> wrote:
Hi Jean-Philippe
There may be a fancier way, but you can just declare a global
in |process_button| to pass the value to a global variable.
Cheers, Jody
>import matplotlib.pyplot as plt x = [] def
process_key(event):
print("Key:", event.key) def process_button(event): global x
print("Button:", event.x, event.y, event.xdata, event.ydata,
event.button) x += [event.xdata] fig, ax = plt.subplots(1, 1)
fig.canvas.mpl_connect('key_press_event', process_key)
fig.canvas.mpl_connect('button_press_event', process_button)
plt.show() print(x) |
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