Develop Reference

communication between Checkbutton and Entry(box)

from tkinter import *
import pandas as pd
df = pd.DataFrame({'item': list('abcde'), 'default_vals': [2,6,4,5,1]})
def input_data(df):
box = Tk()
height = str(int(25*(df.shape[0]+2)))
box.geometry("320x" + height)
box.title("my box")
#initialise
params, checkButtons, intVars = [], [], []
default_vals = list(df.default_vals)
itemList = list(df.item)
for i,label in enumerate(itemList):
Label(box, text = label).grid(row = i, sticky = W)
params.append(Entry(box))
params[-1].grid(row = i, column = 1)
params[-1].insert(i, default_vals[i])
intVars.append(IntVar())
checkButtons.append(Checkbutton(variable = intVars[-1]))
checkButtons[-1].grid(row = i, column = 3)
def sumbit(event=None):
global fields, checked
fields = [params[i].get() for i in range(len(params))]
checked = [intVars[i].get() for i in range(len(intVars))]
box.destroy()
#add submit button
box.bind('<Return>', sumbit)
Button(box, text = "submit",
command = sumbit).grid(row = df.shape[0]+3, sticky = W)
box.focus_force()
mainloop()
return fields, checked
I am new to tkinter and not sure what I a trying to do is possible.
At present, my script (simplified here to a function rather than a class) builds a box with all the default values entered in the fields:
Instead, I want to start with empty fields which, once the corresponding checkButton is clicked will get the default value (should still be able to manually change it through the field as happens now), and also, once any value is entered in a given field, the corresponding checkButton is selected.
Are these possible?

It is possible, but let me preface my solution with a few cautions on your current code:
It's rarely advisable to do a star import (from tkinter import *) as you don't have any control over what gets imported into your namespace. It's more advisable to explicitly import what you need as a reference:
import tkinter as tk
tk.Label() # same as if you wrote Label()
tk.IntVar() # same as if you called IntVar()
The behaviour you wanted, while possible, might not be necessarily user friendly. What happens when a user has already entered something, and unchecks the checkbox? Or what happens if the checkbox was selected and then the user deleted the information? These might be things you want to think about.
Having said that, the solution is to use add a trace callback function over your variable(s). You'll also need to add a StringVar() for the Entry boxes as you wanted a two way connection:
# add strVars as a list of StringVar() for your Entry box
params, checkButtons, intVars, strVars = [], [], [], []
During your iteration of enumerate(itemList), add these:
# Create new StringVar()
strVars.append(StringVar())
# add a trace callback for tracking changes over the StringVar()
strVars[-1].trace_add('write', lambda var, var_idx, oper, idx=i: trace_strVar(idx))
# update your Entry to set textvariable to the new strVar
params.append(Entry(box, textvariable=strVars[-1]))
# similarly, add a trace for your IntVar
intVars[-1].trace_add('write', lambda var, var_idx, oper, idx=i: trace_intVar(idx))
You'll need to define the two trace callback functions before you iterate through the widget creations:
def trace_intVar(idx):
# if Checkbox is checked and Entry is empty...
if intVars[idx].get() and not params[idx].get():
# prefill Entry with default value
params[idx].insert(0, df.default_vals[idx])
def trace_strVar(idx):
# if Entry has something...
if strVars[idx].get():
# and Checkbox is not checked...
if not intVars[idx].get():
# Set the checkbox to checked.
intVars[idx].set(True)
# but if Entry is empty...
else:
# Set the Checkbox to uncheck.
intVars[idx].set(False)
Remember I mentioned the behaviour - I took a little liberty to clear the Checkbox if Entry is empty. If you however don't wish to do that, you'll need to modify the handling a little.
Note on the way the trace_add is written. The callback function is always passed with three default arguments, namely the Variable Name, The Variable Index (if any) and Operation (see this great answer from Bryan Oakley). Since we don't need any in this case (we can't reverse reference the variable name to the linked index between the variable lists), we'll have to manually wrap the callback with another lambda and ignore the three arguments:
lambda var, # reserve first pos for variable name
var_idx, # reserve second pos for variable index
oper, # reserve third pos for operation
idx=i: # pass in i by reference for indexing point
trace_intVar(idx) # only pass in the idx
You cannot just pass lambda...: trace_intVar(i) as i will be passed by value instead of reference in that case. Trust me, I've made this error before. Therefore we pass another argument idx with its default set to i, which will now be passed by reference.
If trace_add doesn't work, use trace('w', ...) instead.
For prosperity, here's the complete implemented solution to your question:
from tkinter import *
import pandas as pd
df = pd.DataFrame({'item': list('abcde'), 'default_vals': [2,6,4,5,1]})
def input_data(df):
box = Tk()
height = str(int(25*(df.shape[0]+2)))
box.geometry("320x" + height)
box.title("my box")
#initialise
params, checkButtons, intVars, strVars = [], [], [], []
default_vals = list(df.default_vals)
itemList = list(df.item)
def trace_intVar(idx):
if intVars[idx].get() and not params[idx].get():
params[idx].insert(0, df.default_vals[idx])
def trace_strVar(idx):
if strVars[idx].get():
if not intVars[idx].get():
intVars[idx].set(True)
else:
intVars[idx].set(False)
for i,label in enumerate(itemList):
Label(box, text = label).grid(row = i, sticky = W)
strVars.append(StringVar())
strVars[-1].trace_add('write', lambda var, var_idx, oper, idx=i: trace_strVar(idx))
params.append(Entry(box, textvariable=strVars[-1]))
params[-1].grid(row = i, column = 1)
#params[-1].insert(i, default_vals[i]) # <-- You don't need this any more
intVars.append(IntVar())
intVars[-1].trace_add('write', lambda var, var_idx, oper, idx=i: trace_intVar(idx))
checkButtons.append(Checkbutton(variable = intVars[-1]))
checkButtons[-1].grid(row = i, column = 3)
def sumbit(event=None):
global fields, checked
fields = [params[i].get() for i in range(len(params))]
checked = [intVars[i].get() for i in range(len(intVars))]
box.destroy()
#add submit button
box.bind('<Return>', sumbit)
Button(box, text = "submit",
command = sumbit).grid(row = df.shape[0]+3, sticky = W)
box.focus_force()
mainloop()
return fields, checked

Option menu in for loop in Python Tkinter

I am trying to create option menus in a loop, and the number of option menus is dependent on a variable. So I'm trying to use exec in my code.
I used the following to pass the value of 'i' to connect to which variable is changing the value.
But once I call the trace, the option I select in the Option menu, does not get updated in the Option menu box. If I do not call the trace funtion, it is getting updated in the display.
trackProcessMenu is the callback function.
Please let me know, where I am making the mistake.
Adding my code:
for i in range(0,numOfLibFiles):
exec('self.processOptionMenuVar_%d = StringVar()'%i)
process_menu = ("ff","ss","tt","fff","sss","ttt")
exec('self.processOptionMenu_%d = OptionMenu(self, self.processOptionMenuVar_%d, *process_menu )'%(i,i))
exec('self.processOptionMenu_%d.config(indicatoron=0,compound=RIGHT,image= self.downArrowImage, anchor = CENTER , direction = RIGHT)'%i)
exec('self.processOptionMenuVar_%d.set("--")'%i)
exec('self.processOptionMenu_%d.grid(row = i, column =1, sticky = N ,padx=30, pady =7 )'%i)
def trackProcessMenu(self,*args):
i = args[0]
exec('process = self.processOptionMenuVar_%d.get()'%i)

You should not use exec this way. A good rule of thumb is that you should never use exec until you can answer the question "why should I never use exec?" :-) exec has it's uses, but this isn't one of them.
Instead of trying to automagically generate variable names, keep your widgets in a list or dictionary.
For example:
option_vars = []
option_menus = []
for i in range(0,numOfLibFiles):
process_menu = ("ff","ss","tt","fff","sss","ttt")
var = StringVar()
om = OptionMenu(self, var, *process_menu)
om.config(indicatoron=0,compound=RIGHT,image= self.downArrowImage, anchor = CENTER , direction = RIGHT)
var.set("--")
om.grid(row = i, column =1, sticky = N ,padx=30, pady =7)
option_vars.append(var)
option_menus.append(om)
With the above, you can now reference the variables and menus with a simple index:
print("option 1 value is:", option_vars[1].get())

Using Entry and updating an entry entered, as the user continues to change the values (using trace method) in TKinter

I am learning Python and I am starting to learn how to use the TKinter GUI. I am making a small interface that does some simple statistical analysis like STDEV, T-tests, etc. I have this method in a class which basically gets the data to work with.
I want the user to be able enter as many data entries as they want (I mean as long as the computer can handle of course). The problem I am having is -- I think when I use the method .get() on an Entry, None is returned?
I am also using method .trace() of DoubleVar() to trace when the values of the entries are updated using the method shown here:
Python Tkinter update when entry is changed
I thought it made sense but it's not working for me. Whenever I change a box in my TK interface, all the other boxes get changed, but the values used to calculate standard deviation are not the numbers that are being shown on the Entry boxes (which are all the same anyways).
Here is the code:
class StandardDeviation:
"""
Runs standard deivation calculations.
"""
def __init__(self) -> None:
"""
Initializes an instance of the functions!
"""
self.stdev_pop = Button(top_frame,
text="Calculate the population "
"standard deviation of the data set")
self.stdev_pop.bind("<Button-1>", self.show_result_population)
self.stdev_pop.pack()
stdev_samp = Button(top_frame,
text="Calculate the sample "
"standard deviation of the data set")
stdev_samp.bind("<Button-1>", self.show_result_sample)
stdev_samp.pack()
self.data = []
self.enter_data = Button(top_frame, text="Enter data")
self.enter_data.bind("<Button-1>", self.pack_add_entry_button)
self.add_entry = Button(top_frame, text="Add data entry",
command=self.add_new_entry)
self.enter_data.pack()
self.all_entries = {}
self.tracer = DoubleVar()
self.tracer.trace("w", self.update)
def pack_add_entry_button(self, *args) -> None:
"""
Pack the add_entry button.
"""
self.add_entry.pack()
def update(self, *args) -> None:
"""
Update the values of the entries.
"""
global update_in_progress
if update_in_progress:
return
update_in_progress = True
data = [str(self.all_entries[item]) for item in self.all_entries]
self.data = [int(item) for item in data if item.isnumeric()]
update_in_progress = False
def add_new_entry(self):
"""
Add a new entry.
"""
new_entry = Entry(root, textvariable=self.tracer)
new_entry.pack()
new_entry_data = new_entry.get()
self.all_entries[new_entry] = new_entry_data
I'm not sure where I'm wrong here if anyone could help me I'd really appreciate it. Thank you!

There is no way to run the code you posted as the indentation is off and some of the buttons call functions that don't exist so this is a standard trace program that shows how to use the tkinter variable associated with the trace, a StringVar in ths case, to get the contents.
import tkinter
def text_changed(*args):
print(tk_name.get())
top = tkinter.Tk()
tk_name=tkinter.StringVar()
tk_name.set("nothing")
tk_name.trace("w", text_changed)
tkinter.Label(top, textvariable=tk_name).grid(row=0, column=1)
entry_1 = tkinter.Entry(top, textvariable=tk_name)
entry_1.grid(row=1, column=1, sticky="W")
entry_1.focus_set()
top.mainloop()

Python 3 Tkinter OptionsMenu

I've been searching around and i am not able to find a proper explanation of the syntax of OptionMenu within Tkinter.
how would i get the current chosen option with in the OptionMenu?
def homeTeamOption(self, frame, sortedList):
def func():
print(homeTeamName)
return
homeTeam = tk.StringVar(frame)
returnValueAwayTeam = []
options = sortedList
homeTeamName = tk.StringVar()
drop = OptionMenu(frame, homeTeamName, *options, command=func())
drop.place(x=200, y= 100, anchor="nw")

To get the value of the OptionMenu you need to get the value of the associated variable. In your case it would be:
homeTeamName.get()
If you want to do this via the command, you must set the option to a reference to the function:
drop = OptionMenu(...command=func)

Python Tkinter label widget doesn't update

Here's a piece of simplified code which doesn't work as i want it to:
def get_tl(self,x):
self.var_tl = IntVar()
if x == "Random (max = 6)":
self.var_tl.set(randint(1,6))
else:
ask_tl = Toplevel()
def destroy_t_set_tl():
self.var_tl.set(entry_tl_t.get())
ask_tl.destroy()
label_tl_t = Label(ask_tl, text="length:").pack(side=LEFT)
entry_tl_t = Entry(ask_tl, width=25)
entry_tl_t.pack(side=LEFT)
button_enter_tl_t = Button(ask_tl, text="Enter", command=destroy_t_set_tl).pack(side=LEFT)
self.label_tl = Label(self, text="length:").grid(row=1,column=0)
# This only shows the right number when "Random (max = 6)". When "Manual" it shows 0
self.show_tl = Label(self, text=self.var_tl.get()).grid(row=1,column=1)
def get_values(self):
# This always shows the right number.
self.total_label = Label(self, text=self.var_tl.get()).grid(row=4,column=0)
The function get_tl is called by an OptionMenu widget which gives x the values: "Manual" or "Random (max = 6)".
When this function is called I want it to choose a random number or open a Toplevel window which ask the user a number through an Entry. After the random number is chosen or the user has given a number. The number needs to be displayed as a label so the user can see if the number is correct.
The label only show the right number when "Random (max = 6)". When "Manual" it shows 0
After a button is pressed the function get_values is called. This however does give the right number regardless if it is manual or random.
I'm probably making a simple mistake here. But I fail to see it.

In this part:
def get_tl(self,x):
self.var_tl = IntVar()
You're recreating the variable over and over again, so it holds the default value of 0, as explained in the documentation:
VALUE is an optional value (defaults to 0)
Then you set the variable only if x == "Random (max = 6)", so in all other cases it will remain at its default.
Possibly you want to remove this line:
self.var_tl = IntVar()
You should have it only in the constructor of your class. Then all your methods will share the same instance pointed by self.var_tl.

This seems to be the answer to my own question:
def get_tl(self,x):
def tl():
self.label_tl = Label(self, text="length:").grid(row=1,column=0)
self.show_tl = Label(self, text=self.var_tl.get()).grid(row=1,column=1)
if x == "Random (max = 6)":
self.var_tl.set(randint(1,6))
tl()
else:
ask_tl = Toplevel()
def destroy_t_set_tl():
self.var_tl.set(entry_tl_t.get())
ask_tl.destroy()
tl()
label_tl_t = Label(ask_tl, text="length:").pack(side=LEFT)
entry_tl_t = Entry(ask_tl, width=25)
entry_tl_t.pack(side=LEFT)
button_enter_tl_t = Button(ask_tl, text="Enter", command=destroy_t_set_tl).pack(side=LEFT)
def get_values(self):
self.total_label = Label(self, text=self.var_tl.get()).grid(row=4,column=0)
Now both the option "Manual" and "Random" will call the function tl() which will show the number so the user can check it.
I also moved the self.var_tl = IntVar() to the constructor of the class. It might not be the optimal solution but for me it works.