Update Tkinter Label from variable

Question

I wrote a Python script that does some task to generate  and then keep changing some text stored as a string variable  This works  and I can print the string each time it gets changed   I can get the Label to display the string for the first time  but it never updates    Here s my code   from tkinter import    outputText    Ready  counter   int 0   root   Tk   root maxsize 400  400   var   StringVar    l   Label root  textvariable var  anchor NW  justify LEFT  wraplength 398  l pack    var set outputText   while True      counter   counter   1     outputText   result     outputText   result     outputText   result     if counter    5          break  root mainloop     The Label will show Ready  but won t update to change that to the strings as they re generated later   After a fair bit of googling and looking through answers on this site  I thought the solution might be to use update idletasks  I tried putting that in after each time the variable was changed  but it didn t help

User · Answer

Maybe I m not understanding the question but here is my simple solution that works -    I want to Display total heads bent this machine so I define a label - TotalHeadsLabel3   Label leftFrame  TotalHeadsLabel3 config font Helv12 fg  blue  text  Total heads     str TotalHeads   TotalHeadsLabel3 pack side TOP     I update the int variable adding the quantity bent - TotalHeads   TotalHeads   headQtyBent   update ready to write to file  amp  display TotalHeadsLabel3 config text  Total Heads   str TotalHeads     update label with new qty   I agree that labels are not automatically updated but can easily be updated with the    lt label name gt  config text   lt new text gt     str  lt variable name gt      That just needs to be included in your code after the variable is updated

User · Answer

This is the easiest one   Just define a Function and then a Tkinter Label  amp  Button   Pressing the Button changes the text in the label  The difference that you would when defining the Label is that use the text variable instead of text  Code is tested and working      from tkinter import       master   Tk            def change text            my var set  quot Second click quot            my var   StringVar       my var set  quot First click quot       label   Label mas textvariable my var fg  quot red quot       button   Button mas text  quot Submit quot  command   change text      button pack       label pack            master mainloop

User · Answer

The window is only displayed once the mainloop is entered  So you won t see any changes you make in your while True block preceding the line root mainloop     GUI interfaces work by reacting to events while in the mainloop  Here s an example where the StringVar is also connected to an Entry widget  When you change the text in the Entry widget it automatically changes in the Label  from tkinter import    root   Tk   var   StringVar   var set  hello    l   Label root  textvariable   var  l pack    t   Entry root  textvariable   var  t pack    root mainloop     the window is now displayed  I like the following reference  tkinter 8 5 reference  a GUI for Python  Here is a working example of what you were trying to do  from tkinter import   from time import sleep  root   Tk   var   StringVar   var set  hello    l   Label root  textvariable   var  l pack    for i in range 6       sleep 1    Need this to slow the changes down     var set  goodbye  if i 2 else  hello       root update idletasks    root update Enter event loop until all pending events have been processed by Tcl

[python] Update Tkinter Label from variable

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