How to hand over a dataframe between tkinter buttons? - python-3.x

Question

I'm pretty new with python programming and this is my first question asked, so be gentle with me. Right now i am working on a tkinter GUI that reads CSV files, turns them into dataframes to edit them and save the processed file to a result.csv in a datapath. My Problem is that i want to read in the CSV with a function OpenFile() connected to one button and then use the returned dataframe in my "Editfunctions" that each also is connected to a button. That doesnt seem to work with my callback in the code. Here is what my tkinter GUI currently Looks like:
root = tk.Tk()
openbutton = tk.Button (root, text='OpenFile', command = lambda: OpenFile())
openbutton.pack()
brakebutton = tk.Button (root, text = 'EditFile', command = lambda: EditFile(z))
brakebutton.pack()
savenewbutton = tk.Button(root, text = 'SavetoNewFile', command = lambda: SaveinNewFile(out_tup_end3))
savenewbutton.pack()
saveexcbutton = tk.Button(root, text = 'AppendtoExistingFile', command = lambda: SavetoexistingFile(out_tup_end3))
saveexcbutton.pack()
root.mainloop()
MY functions essentially look like this:
def OpenFile():
name = askopenfilename()
df = pd.read_csv(name, sep = ';')
return df
def EditFile(z):
df1 = z[[]]
.
.
.
.
return out_tup_end3
def SaveinNewFile(out_tup_end3):
out_tup_end3.to_csv("datapath", sep = ';', index = 0, mode = 'w')
def SavetoexistingFile(out_tup_end3):
with open("datapath", 'a') as f:
out_tup_end3.to_csv(f, header=False, sep = ';', index = 0)
def main():
z = OpenFile()
EditFile(z)
editedFile = EditFile(z)
SaveinNewFile(editedFile)
SavetoexistingFile(editedFile)
if __name__ == "__main__":
main()
So I think the not properly working part is that the callback is not handing over the dataFrame read from OpenFile() to EditFile(z). How can i achieve that?
Thanks for the help in advance!!

Answer 1

command= executes function but it doesn't care of value returned from this function so you have to use global variables to use result from one function in other function.
You code could look like this
#!/usr/bin/env python3
import tkinter as tk
from tkinter.filedialog import askopenfilename
from tkinter.messagebox import showinfo, showwarning
import pandas as pd
# --- functions ---
def open_file():
# inform function to use global variables
global df
name = askopenfilename()
if name:
df = pd.read_csv(name, sep=';')
showinfo("INFO", "DataFrame created")
def edit_file():
# inform function to use global variables
global df, out_tup_end3
if df is None:
#print("Read file first")
showwarning("WARNING", "Read file first")
else:
df1 = df[[]]
# ...
out_tup_end3 = df1
showinfo("INFO", "DataFrame edited")
def save_in_new_file():
# inform function to use global variables
global out_tup_end3
if out_tup_end3 is None:
#print("Read file first")
showwarning("WARNING", "Read file first")
else:
out_tup_end3.to_csv("datapath", sep=';', index=0, mode='w')
showinfo("INFO", "DataFrame saved")
def save_to_existing_file():
# inform function to use global variables
global out_tup_end3
if out_tup_end3 is None:
#print("Read file first")
showwarning("WARNING", "Read file first")
else:
with open("datapath", 'a') as f:
out_tup_end3.to_csv(f, header=False, sep=';', index=0)
showinfo("INFO", "DataFrame appended")
# --- main ---
if __name__ == "__main__":
# create global variables
df = None
out_tup_end3 = None
# GUI
root = tk.Tk()
b = tk.Button(root, text='Open File', command=open_file)
b.pack(fill='x')
b = tk.Button(root, text='Edit File', command=edit_file)
b.pack(fill='x')
b = tk.Button(root, text='Save to New File', command=save_in_new_file)
b.pack(fill='x')
b = tk.Button(root, text='Append to Existing File', command=save_to_existing_file)
b.pack(fill='x')
root.mainloop()
Or learn how to use classes and self. instead of global