I have a plot imbedded in my GUI and I want to add a cursor to display the x and y coordinates as I hover over the plot

Question

Plot displaying properly

x=[]
y=[]    
figure = Figure(figsize=(5, 4), dpi=100) 
plot = figure.add_subplot(1, 1, 1)
figure.suptitle(Date, fontsize=12)
plot.plot(x, y, color="blue")
cursor = Cursor(plot,horizOn=True,vertOn=False,color="green",linewidth=2.0)
canvas = FigureCanvasTkAgg(figure, root)                    
canvas.get_tk_widget().grid(column=0, row=3,columnspan=4,pady = 4, padx=4)

cursor = Cursor() takes ax and it seems i cant put plot.axes

You can bind the canvas and get x, y coordinates using event.x and event.y — , Jun 02 '21 at 09:19
`Cursor` is for having a crosshair where your cursor currently is. For having a crosshair to the closest data point from your cursor and displaying the coordinates, you need a mouse event where you get the x/y coordinates of your mouse and then figure out what the closest data point in your graph is to set your vertical/horizontal lines + text. See [this answer](https://stackoverflow.com/questions/44679473/add-cursor-to-matplotlib) for an example. — Reti43, Jun 02 '21 at 09:27

acw1668 · Accepted Answer · 2021-06-02T10:21:53.530

0

You need to create the Cursor instance after creating the canvas:

canvas = FigureCanvasTkAgg(figure, root)
canvas.get_tk_widget().grid(column=0, row=3,columnspan=4,pady = 4, padx=4)

cursor = Cursor(plot, horizOn=True, vertOn=False, color="green", linewidth=2.0)

Full example code:

import tkinter as tk
from matplotlib.backends.backend_tkagg import (FigureCanvasTkAgg, NavigationToolbar2Tk)
from matplotlib.figure import Figure
from matplotlib.widgets import Cursor

Date = "2021-06-01"

root = tk.Tk()

x = []
y = []

figure = Figure(figsize=(5, 4), dpi=100)
plot = figure.add_subplot(1, 1, 1)
#print(plot)
figure.suptitle(Date, fontsize=12)
plot.plot(x, y, color="blue")

canvas = FigureCanvasTkAgg(figure, root)
canvas.get_tk_widget().grid(column=0, row=3,columnspan=4,pady = 4, padx=4)

# pack_toolbar=False will make it easier to use a layout manager later on.
toolbar = NavigationToolbar2Tk(canvas, root, pack_toolbar=False)
toolbar.update()
toolbar.grid(sticky="ew")

cursor = Cursor(plot, useblit=True, horizOn=True, vertOn=True, color="green", linewidth=2.0)

root.mainloop()

And the output:

edited Jun 02 '21 at 10:21

answered Jun 02 '21 at 09:37

acw1668

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I tried it and did not work, because I don't know if Cursor(plot,...) is correct or not. every documentation is using Cursor(ax,...) where ax are the axes – Joe_bart Jun 02 '21 at 09:54
@Joe_bart It works for me. Note that `plot` is of type `AxesSubplot`. You can use `print(plot)` to verify it. – acw1668 Jun 02 '21 at 09:56
correct print(plot) gives me AxesSubplot(0.125,0.11;0.775x0.77), but still no sign of cursor when i run the GUI – Joe_bart Jun 02 '21 at 10:07
I can see a horizontal green line following the cursor when hover on the plot. – acw1668 Jun 02 '21 at 10:09
weird. Is the plot in the GUI? or outside on a separate window? it works if its outside of the GUI like a new window, but inside still not working – Joe_bart Jun 02 '21 at 10:17
My code is based on yours and yours is embedded inside a tkinter window. – acw1668 Jun 02 '21 at 10:18
@Joe_bart I have posted my example as reference. – acw1668 Jun 02 '21 at 10:23
just tried your code it works! I think my issue is that my data is too large because on small data it's working very fine. – Joe_bart Jun 02 '21 at 10:30
or maybe even my grid layout is the issue – Joe_bart Jun 02 '21 at 10:32

I have a plot imbedded in my GUI and I want to add a cursor to display the x and y coordinates as I hover over the plot

1 Answers1