Update plot, remove old data show new data

[g3blv]

Thanks for an amazing library!

I'm trying to create an application where the user can select a ticker and then click a button that prints candlesticks for the ticker. I'm plotting the graph inside a frame in Tkinter.

The user can select a ticker in the drop down and Graph the data for the ticker.

I first create the empty graph

def _make_empty_graph(self):

    self.fig = mpf.figure()     
    self.canvas = FigureCanvasTkAgg(self.fig, self.graph_frame)
    self.canvas.get_tk_widget().pack()

I then create the graph with data from a dataframe, after the user has selected a ticker and clicked "Graph". I destroy the children in the frame to not add another graph under the previous graph. The user can then select yet another ticker and graph it.

def _make_graph(self, ticker_data=None):

    self._get_ticker_data()

    for widgets in self.graph_frame.winfo_children():
        widgets.destroy()

    self.fig, _ = mpf.plot(self.ticker_df, type='candle', 
        title = f'{self.ticker_var.get()}',
        volume=True, style='binance', returnfig=True)


    self.canvas = FigureCanvasTkAgg(self.fig, self.graph_frame)
    self.canvas.get_tk_widget().pack()

Can I solve this a bit more elegant by using subplots or similar and then just clear the graph before I create the new graph? I still want to show an empty graph in the beginning. Do I need to create the empty graph in some other way to be able to update it later? Later on I like to add buttons to be able to RSI, Bollinger bands etc. on top the candlesticks.

Suggestions are greatly appreciated.

[DanielGoldfarb]

I don't know if this will work (and don't have time now to test it myself) but have you tried this: Instead of destroying ... save the axes list:

self.fig, self.axlist = mpf.plot(..., returnfig=True)

Then when you want a black graph:

for ax in self.axlist:
    ax.clear()

Please let me know if that works.

If it does work, then in theory you will only need to ever call _make_empty_graph() one time at the beginning.

Then do the ax.clear() stuff just before plotting each new ticker.

You also may need to modify _make_graph() so that the first time it is called it uses returnfig=True but on subsequent calls it passes in the Axes objects. This is not unlike the animation example here. For more information see also external axes mode.

[g3blv]

Thank you very much. i wasn't able to solve it by clearing the the ax. Seems like I have to use destroy() when using a canvas in Tkinter.

refresh matplotlib figure in a tkinter app

[DanielGoldfarb]

@g3blv Thank you for the update. Much appreciated. I don't know much about tkinter, however we do get several mplfinance/tkinter related questions from time to time. I appreciate your taking the time to post here. Thank you.

[Anshika91]

please assign this task to me ...

[DanielGoldfarb]

@Anshika91

What is it that you are planning to do regarding this issue?