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I have been programming for a long time. Only recently have I decided to take a stab at python (I should be working with C# as I am in school for it, but I don't care for windows. Long story)

Anyway I was on this site and it showed source for a calculator. I took it, and put it in PyCharm and started to study. By the time I was done I had changed the source significantly. I had added keyboard binding and reduced a lot of the redundant code in it.

My question is simple, is this code that I wrote efficient from a python standard viewpoint?

# -*-coding: utf-8-*-
# !/usr/bin/python3.5
from tkinter import Tk, Button, Entry, END
import math
class Calc:
 def getandreplace(self): # replace x, + and % to symbols that can be used in calculations
 # we wont re write this to the text box until we are done with calculations
 self.txt = self.e.get() # Get value from text box and assign it to the global txt var
 self.txt = self.txt.replace('÷', '/')
 self.txt = self.txt.replace('x', '*')
 self.txt = self.txt.replace('%', '/100')
 def evaluation(self, specfunc): # Evaluate the items in the text box for calculation specfunc = eq, sqroot or power
 self.getandreplace()
 try:
 self.txt = eval(str(self.txt)) # evaluate the expression using the eval function
 except SyntaxError:
 self.displayinvalid()
 else:
 if any([specfunc == 'sqroot', specfunc == 'power']): # Square Root and Power are special
 self.txt = self.evalspecialfunctions(specfunc)
 self.refreshtext()
 def displayinvalid(self):
 self.e.delete(0, END)
 self.e.insert(0, 'Invalid Input!')
 def refreshtext(self): # Delete current contents of textbox and replace with our completed evaluatioin
 self.e.delete(0, END)
 self.e.insert(0, self.txt)
 def evalspecialfunctions(self, specfunc): # Calculate square root and power if specfunc is sqroot or power
 if specfunc == 'sqroot':
 return math.sqrt(float(self.txt))
 elif specfunc == 'power':
 return math.pow(float(self.txt), 2)
 def clearall(self): # AC button pressed on form or 'esc" pressed on keyboard
 self.e.delete(0, END)
 self.e.insert(0, '0')
 def clear1(self, event=None):
 # C button press on form or backspace press on keyboard event defined on keyboard press
 
 if event is None:
 self.txt = self.e.get()[:-1] # Form backspace done by hand
 else:
 self.txt = self.getvalue() # No need to manually delete when done from keyboard
 self.refreshtext()
 def action(self, argi: object): # Number or operator button pressed on form and passed in as argi
 self.txt = self.getvalue()
 self.stripfirstchar()
 self.e.insert(END, argi)
 def keyaction(self, event=None): # Key pressed on keyboard which defines event
 self.txt = self.getvalue()
 if any([event.char.isdigit(), event.char in '/*-+%().']):
 self.stripfirstchar()
 elif event.char == '\x08':
 self.clear1(event)
 elif event.char == '\x1b':
 self.clearall()
 elif event.char == '\r':
 self.evaluation('eq')
 else:
 self.displayinvalid()
 return 'break'
 def stripfirstchar(self): # Strips leading 0 from text box with first key or button is pressed
 if self.txt[0] == '0':
 self.e.delete(0, 1)
 def getvalue(self): # Returns value of the text box
 return self.e.get()
 def __init__(self, master): # Constructor method
 self.txt = 'o' # Global var to work with text box contents
 master.title('Calulator')
 master.geometry()
 self.e = Entry(master)
 self.e.grid(row=0, column=0, columnspan=6, pady=3)
 self.e.insert(0, '0')
 self.e.focus_set() # Sets focus on the text box text area
 # Generating Buttons
 Button(master, text="=", width=10, command=lambda: self.evaluation('eq')).grid(row=4, column=4, columnspan=2)
 Button(master, text='AC', width=3, command=lambda: self.clearall()).grid(row=1, column=4)
 Button(master, text='C', width=3, command=lambda: self.clear1()).grid(row=1, column=5)
 Button(master, text="+", width=3, command=lambda: self.action('+')).grid(row=4, column=3)
 Button(master, text="x", width=3, command=lambda: self.action('x')).grid(row=2, column=3)
 Button(master, text="-", width=3, command=lambda: self.action('-')).grid(row=3, column=3)
 Button(master, text="÷", width=3, command=lambda: self.action('÷')).grid(row=1, column=3)
 Button(master, text="%", width=3, command=lambda: self.action('%')).grid(row=4, column=2)
 Button(master, text="7", width=3, command=lambda: self.action('7')).grid(row=1, column=0)
 Button(master, text="8", width=3, command=lambda: self.action('8')).grid(row=1, column=1)
 Button(master, text="9", width=3, command=lambda: self.action('9')).grid(row=1, column=2)
 Button(master, text="4", width=3, command=lambda: self.action('4')).grid(row=2, column=0)
 Button(master, text="5", width=3, command=lambda: self.action('5')).grid(row=2, column=1)
 Button(master, text="6", width=3, command=lambda: self.action('6')).grid(row=2, column=2)
 Button(master, text="1", width=3, command=lambda: self.action('1')).grid(row=3, column=0)
 Button(master, text="2", width=3, command=lambda: self.action('2')).grid(row=3, column=1)
 Button(master, text="3", width=3, command=lambda: self.action('3')).grid(row=3, column=2)
 Button(master, text="0", width=3, command=lambda: self.action('0')).grid(row=4, column=0)
 Button(master, text=".", width=3, command=lambda: self.action('.')).grid(row=4, column=1)
 Button(master, text="(", width=3, command=lambda: self.action('(')).grid(row=2, column=4)
 Button(master, text=")", width=3, command=lambda: self.action(')')).grid(row=2, column=5)
 Button(master, text="√", width=3, command=lambda: self.evaluation('sqroot')).grid(row=3, column=4)
 Button(master, text="x2", width=3, command=lambda: self.evaluation('power')).grid(row=3, column=5)
 # bind key strokes
 self.e.bind('<Key>', lambda evt: self.keyaction(evt))
# Main
root = Tk()
obj = Calc(root) # object instantiated
root.mainloop()

I don't really care for the names of some of the function names and variable names. I like using descriptive names, so names like self.e would have been called self.textbox or something. so these things are leftovers from the web copy I found and haven't changed them.