[Matplotlib-users] selecting points inside plot

[Jody Klymak]

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)

```

On 2 Sep 2017, at 7:01, Jean-Philippe Grivet wrote:

> Hi
> Thank you for the very interesting refeerences.  However, I find that 
> the various programs are rather
> involved and that they do not exactly answer my needs. The simplest 
> program is probably the following
> (from the boook by B. Root). It seems to be a step in the right 
> direction!
>
> import matplotlib.pyplot as plt
>
> def process_key(event):
>     print("Key:", event.key)
> def process_button(event):
>     print("Button:", event.x, event.y, event.xdata, event.ydata, 
> event.button)
>
> 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()
>
> So now, how do I retrieve the values event.xdata, event.ydata s(everal 
> times) in
> order to use them in the main program ? (By the way, this is pretty 
> easy
> in Matlab: the function xclick the mouse coordinates and index of the 
> button
> pressed).
> Thank you soluch for your help.
> JP Grivet
>
>
> Le 30/08/2017 04:13, Thomas Caswell a écrit :
>> Jean,
>>
>> What you want to do is totally possible!
>>
>> I suggest having a look at the examples in 
>> https://matplotlib.org/examples/widgets/index.html the `ginput` 
>> method, https://github.com/tacaswell/interactive_mpl_tutorial and Ben 
>> Root's book 
>> https://www.amazon.com/Interactive-Applications-using-Matplotlib-Benjamin/dp/1783988843
>>
>> Tom
>>
>
>
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