Tkinter remove stored file from memory - python-2.7

Question

from Tkinter import *
import Tkinter as tk
import ttk
import tkFileDialog
import numpy as np
import matplotlib
matplotlib.use("TkAgg")
import matplotlib.pyplot as plt
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2TkAgg
from matplotlib.figure import Figure
class Look():
def __init__(self, master):
self.master = master
self.master.title("Demo")
self.master.configure(background = "grey91") #the color will be changed later
self.master.minsize(500, 300) # width + height
self.master.resizable(False, False)
self.top_frame = ttk.Frame(self.master, padding = (10, 10))
self.top_frame.pack()
ttk.Button(self.top_frame, text = "Load file", command = self.load_file,
style = "TButton").pack()
ttk.Button(self.top_frame, text = "Reset", command = self.clear_file,
style = "TButton").pack()
ttk.Button(self.top_frame, text = "Plot", command = self.plot_file,
style = "TButton").pack()
self.bottom_frame = ttk.Frame(self.master, padding = (10, 10))
self.bottom_frame.pack()
self.fig = plt.figure(figsize=(12, 5), dpi=100) ##create a figure; modify the size here
self.fig.add_subplot()
plt.title("blah")
self.canvas = FigureCanvasTkAgg(self.fig, master = self.bottom_frame)
self.canvas.show()
self.canvas.get_tk_widget().pack(side=tk.TOP, fill=tk.BOTH, expand=1)
self.toolbar = NavigationToolbar2TkAgg(self.canvas, self.bottom_frame)
self.toolbar.update()
self.canvas._tkcanvas.pack(side=tk.TOP, fill=tk.BOTH, expand=1)
def load_file(self):
self.file = tkFileDialog.askopenfilename(defaultextension = ".txt", filetypes = [("Text Documents", "*.txt")])
def clear_file(self):
self.fig.clf()
self.fig.add_subplot()
plt.xticks()
plt.yticks()
self.canvas.draw()
def plot_file(self):
self.r, self.g = np.loadtxt(self.file).transpose()
self.fig.clf()
plt.plot(self.r, self.g)
self.canvas.show()
def main():
root = Tk()
GUI = Look(root)
root.mainloop()
if __name__ == "__main__": main()
The code above creates a program has three buttons. The Load file buttom loads a txt file, Reset button is supposed to clear the plot and delete the file just loaded into the memory. Plot button is to plot the figure onto canvas below.
I have a question about how to write function associated with Reset function, i.e. clear_file function. Currently what it does is just clear the plot from canvas. But it seems the file that has been loaded to plot is stored in memory, since click again Plot, it will display the plot. My goal is to use Reset button to bring it to a fresh start--nothing stored in memory. I know loading a new file will overwrite the previous file. But when there are multiple buttons for loading different files, the situations could become complicated. Therefore I hope Reset can do the job.
If you want to try this little program, you may create a simple txt with two column data to be loaded into the program.
Thanks.

Answer 1

I would make 2 changes. Move the code that sets up your plot into its own method and reset the frame each time the method is called. This can be done with destroying the frame and remaking it. The 2nd change I would change the command on your reset to reference this new method.
Taking your code this is what I would change to be able to reset the plot.
import tkinter as tk
import tkinter.ttk as ttk
from tkinter import filedialog
import numpy as np
import matplotlib
matplotlib.use("TkAgg")
import matplotlib.pyplot as plt
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2TkAgg
from matplotlib.figure import Figure
class Look():
def __init__(self, master):
self.master = master
self.master.title("Demo")
self.master.configure(background = "grey91") #the color will be changed later
self.master.minsize(500, 300) # width + height
self.master.resizable(False, False)
self.top_frame = ttk.Frame(self.master, padding = (10, 10))
self.top_frame.pack()
ttk.Button(self.top_frame, text = "Load file", command = self.load_file,style = "TButton").pack()
ttk.Button(self.top_frame, text = "Reset", command = self.new_plot,style = "TButton").pack()
ttk.Button(self.top_frame, text = "Plot", command = self.plot_file,style = "TButton").pack()
self.bottom_frame = ttk.Frame(self.master, padding = (10, 10))
self.bottom_frame.pack()
self.new_plot()
# this function will reset your plot with a fresh one.
def new_plot(self):
self.bottom_frame.destroy()
self.bottom_frame = ttk.Frame(self.master, padding = (10, 10))
self.bottom_frame.pack()
self.fig = plt.figure(figsize=(12, 5), dpi=100) ##create a figure; modify the size here
self.fig.add_subplot()
plt.title("blah")
self.canvas = FigureCanvasTkAgg(self.fig, master = self.bottom_frame)
self.canvas.show()
self.canvas.get_tk_widget().pack(side=tk.TOP, fill=tk.BOTH, expand=1)
self.toolbar = NavigationToolbar2TkAgg(self.canvas, self.bottom_frame)
self.toolbar.update()
self.canvas._tkcanvas.pack(side=tk.TOP, fill=tk.BOTH, expand=1)
def load_file(self):
self.file = filedialog.askopenfilename(defaultextension = ".txt", filetypes = [("Text Documents", "*.txt")])
def clear_file(self):
self.fig.clf()
self.fig.add_subplot()
plt.xticks()
plt.yticks()
self.canvas.draw()
def plot_file(self):
self.r, self.g = np.loadtxt(self.file).transpose()
self.fig.clf()
plt.plot(self.r, self.g)
self.canvas.show()
if __name__ == "__main__":
root = tk.Tk()
GUI = Look(root)
root.mainloop()