Develop Reference

Recreate left-to-right scrolling text in tkinter

I want to create a fast typing effect through packing a label in tkinter. When I run this code, it prints left to right as I want it to, but the letters are spaced far apart and the spaces print {} brackets instead.
How can I remove the brackets and just show a space? Is there also a cleaner and easier way to do the scrolling effect other than the list method I used?
root = Tk()
delay = 50
label_var = StringVar()
label = Label(root, textvariable=label_var, height=10)
num = 0
def scroll():
global num
roll_text = list(message) # Edit: deleted this line
num = num + 1
label_var.set(roll_text[1:num]) # Edit: changed roll_text to message
root.after(delay, scroll)
message = ' This message should be scrolling left to right. '
scroll()
label.pack()
root.mainloop()

The brackets are appearing because you're converting the string to a list. When tkinter is given a list where it expects a string it uses Tcl's rules for converting the list back to a string. Those rules include using curly braces to preserve the original data.
The solution is simple: don't pass a list to label_var.set.
As for the alignment, because you don't provide any alignment options, tkinter will try to center the widget. A simple solution for this specific case is to pass side='left' to the pack command.

How to add Combobox every time when i press button in Tkinter?

I wanna build GUI and there is a button which Combobox adds every time the button is pressed. but i cant find out how to figure or code this concept
And, is there any other Widget? or is there other way to build my concept??
please some one help me..
the main concept without using tkinter is Like this shown . i want this concept to be made in Tkinter.
[THIS IS WHAT I TRIED BUT WHENEVER I PRESS THE BUTTON, ALL COMBOBOX ADDED WORKS TOGETHER (which means when i change the list name, all combobox also changes..)]
def Plus_EXT():
button_plus = Button(window3,justify = CENTER,command = Add_EXT, text= "+")
button_plus.grid(row=0,column=0)
def Add_EXT():
global Num
window3.update()
Num += 1
CEList1 = [x for x in os.listdir(cur_dir) if ('CE' in x.upper()) and ('.rpt' in x)]
RPT_EXT_file=ttk.Combobox(window3, values=CEList1,textvariable= EXT_String)
RPT_EXT_file.grid(row=8+Num,column=1)
RPT_EXT_file.set("FILE")
[MAIN CONCEPT WITHOUT USING TKINTER]
CE_Num= int(input("How Many EXTRA Chordae?: "))
User_File = input("Type the New File Name: ")
for Num_Of_EXT in range(CE_Num):
RPT_EXT_file = input("Type the RPT of EXTRA CHORDAE: ") + ".rpt"
EXTRA(User_File,RPT_EXT_file,Num_Of_EXT)
EXTRA_PLT(User_File,Num_Of_EXT)
the output i want is { everytime i press the button a new Combobox is added in the frame with the lists which works separately.}

The issue is that all your Combobox widgets are linked with same textvariable called EXT_String.So when you change the value of one Combobox widget, it updates same value in all of them.
I would suggest to keep a list of such variables and index that list using NUM in your loop to assign the textvariable.
UPDATE:
Just an example based on limited code shared in Add_EXT method:
global var_list
var_list.append(IntVar()) #Or StringVar(), whatever you are using
RPT_EXT_file=ttk.Combobox(window3, values=CEList1,textvariable=var_list[-1])

Scale with variable resolution [duplicate]

Is it possible to have a slider (Scale widget in tkinter) where the possible values that are displayed when manipulating the slider are discrete values read from a list?
The values in my list are not in even steps and are situation dependent.
From all the examples I've seen, you can specify a minimum value, a maximum value and a step value (n values at a time), but my list might look like this:
list=['0', '2000', '6400', '9200', '12100', '15060', '15080']
Just as an example. To reiterate, I want it go from for instance list[0] to list[1] or list[6] to list[5] when pulling the slider.
If anyone has any other suggestion for easily being able to pick a value from hundreds of items in a list, I'm all ears. I tried the OptionMenu widget but it gets to extensive and hard get a view of.

Edit you could set the command of the slider to a callback, have that callback compare the current value to your list and then jump to the nearest by calling set() on the slider
so:
slider = Slider(parent, from_=0, to=100000, command=callback)
and:
def callback(event):
current = event.widget.get()
#compare value here and select nearest
event.widget.set(newvalue)
Edit:
to show a complete (but simple example)
try:
import tkinter as tk
except ImportError:
import Tkinter as tk
valuelist = [0,10,30,60,100,150,210,270]
def valuecheck(value):
newvalue = min(valuelist, key=lambda x:abs(x-float(value)))
slider.set(newvalue)
root = tk.Tk()
slider = tk.Scale(root, from_=min(valuelist), to=max(valuelist), command=valuecheck, orient="horizontal")
slider.pack()
root.mainloop()
i've tested this in python 2.7.6 and 3.3.2, even when dragging the slider this jumps to the nearest value to where the mouse is currently as opposed to only jumping when you let go of the slider.

Tkinter radio button clear / reset values

I am writing a Tkinter program for the first time and have a question on radio buttons. What I am trying to do is this:
open a set of images (one at a time).
When an image is opened, annotate a value using the radio button.
Collect this value in a list
So, in this example I have 2 compounds and the list would have 2 annotations.
The problem I have is, if by mistake the user clicks radiobutton 2 instead of one, and then corrects him/herself, the list will have 4 items (3 for the first image, 1 for the second). How do I handle this, so that the list will have only 2 values?
import Tkinter as tk
from PIL import ImageTk, Image
from tkFileDialog import askopenfilename
cmp_list = ["VU435DR","VU684DR"]
li = []
li_final = []
def sel():
selection = str(var.get())
if selection == "1":
li.append("Antagonist")
elif selection == "2":
li.append("Agonist")
for i in range(len(cmp_list)):
root = tk.Tk()
var = tk.IntVar()
ig = str(cmp_list[i] + '.png')
img = ImageTk.PhotoImage(Image.open(ig))
panel = tk.Label(root,image=img)
panel.pack(side = "top",fill="none",expand="no")
#w = tk.Text(height=2,width=50)
#w.pack(side='right")
q = tk.Radiobutton(root,text="Antagonist",command=sel,value=1,variable=var)
q.pack()
r = tk.Radiobutton(root,text="Agonist",command=sel,value=2,variable=var)
r.pack()
root.mainloop()
print li

Your code is creating more than one instance of tk.Tk(). This is not how Tkinter was designed to work, and it will yield unpredictable behavior. A proper Tkinter program always has exactly one instance of tk.Tk().
If you need more than one window, for the second and subsequent windows you should create an instance of tk.Toplevel.
To answer your specific question about how to handle someone first hitting one radiobutton and then the other -- the problem is that you are unconditionally appending to your list each time they click on a radiobutton. The solution is to use some sort of flag or indicator to know whether one of the radiobuttons has been clicked, or change your code so that it doesn't matter.
Let's look at that second option - make it so it doesn't matter. When you open up a new image you can automatically append a value to your list. In this case, set it to None to say that nothing has been picked yet. Then, in sel, you would always replace the last element rather than append a new element, since you know that the last element always refers to the current compound.

Finding widgets on a grid (tkinter)

Using the tkinter module, suppose I create a grid with 50 button widgets and each of those widgets has different text. I need to be able to specify some way of typing in a row and column so I can get that widget's text at that location.
For example, if I need the widget's text at the third row in the second column of the grid. I've searched the docs but that tells me how to get info about widgets, when I need info about the grid.

There's no need to create your own function or keep a list/dictionary, tkinter already has a built-in grid_slaves() method.
It can be used as frame.grid_slaves(row=some_row, column=some_column)
Here's an example with a grid of buttons showing how grid_slaves() retrieves the widget, as well as displaying the text.
import tkinter as tk
root = tk.Tk()
# Show grid_slaves() in action
def printOnClick(r, c):
widget = root.grid_slaves(row=r, column=c)[0]
print(widget, widget['text'])
# Make some array of buttons
for r in range(5):
for c in range(5):
btn = tk.Button(root, text='{} {}'.format(r, c),
command=lambda r=r, c=c: printOnClick(r, c))
btn.grid(row=r, column=c)
tk.mainloop()

You got a previous answer relative to a method to save button objects in a dictionary in order to recover them using their (column, row) position in a grid.
So if self.mybuttons is your dictionary of lists of buttons as described in previous answer, then you can get the text at position row, col as this:
abutton = self.mybuttons[arow][acolumn]
text_at_row_col = abutton["text"]
On the other hand, if what you need is to get the text from the button callback:
button.bind("<Button-1>", self.callback)
then you can get the button text from the event, you do not need to know its row/col position, only to press it:
def callback(self, event):
mybutton = event.widget
text_at_row_col = mybutton["text"]