Gibt es eine bessere Möglichkeit, die Zeichenfolge für die Auswertung zu ändern?

Question

Gibt es eine bessere Möglichkeit, eine der Zahlen zu ändern, um in der Division zu schweben? Ich habe derzeit 1 Schleife, die meine Gleichung nach '/' scanne und zweite, die Nummer nach '/' nehmen und ändern sie in float. Wie kann ich es verbessern?

#!/usr/bin/env python2.7 

import Tkinter as tk 


main = tk.Tk() 
main.title('Calculator') 


def insert_variable(i): 
    """Inserts the user defined sign and puts it on the end the entry widget""" 
    END = len(calc_entry.get()) 
    calc_entry.insert(END,i) 

def calculate(): 
    ''' deletes all characters in the entry and inserts evaluation of the equation ''' 
    equation = calc_entry.get() 
    try: 
     calc_entry.delete(0, len(equation)) # deletes all characters in the entry 
     for i in range(len(equation)-1):# loop for checking for special signs 


      if equation[i] == '/': #if there is '/' sign change one of numbers to float 
       for j in range(i+1,len(equation)): # loop for number of digits after '/' sign 
        if equation[j] == '.': # if there is dot go ones more 
         pass 
        else: 
         try: 
          int(equation[j])# if there is something other than digit go to exception 
         except ValueError: 
          equation = equation[:i+1] + str(float(equation[i+1:j])) + equation[j:]# change number after/to float and join all strings 
          break 

      if equation[i] == '^': # if there is^sign change it for '**' 
       equation = equation[:i] +'**'+ equation[i+1:] 
       print equation 


     calc_entry.insert(0, str(round(eval(equation), 3))) # evaluates (calculates) the equation after loop 

    except SyntaxError: 
     calc_entry.insert(0,'<ERROR>') 
    except ZeroDivisionError: 
     calc_entry.insert(0,'ERROR DIVISION BY 0') 

calc_entry = tk.Entry(main) # creates an entry 
calc_entry.grid(row =1, columnspan = 6) 


bEquate = tk.Button(main, text="=", command = calculate) 
bEquate.grid(row=5, column=3) 

bDivision = tk.Button(main, text="/", command = lambda : insert_variable("/")) 
bDivision.grid(row=3, column=5) 

main.mainloop() 

Was passiert, wenn ich sqrt() Funktion haben, die sqrt Zeichen zur letzten Nummer gibt? Wie kann ich es in die calculate() Funktion implementieren?

sqrtChr = unichr(0x221A) 
def insert_sqrt(): 
    """inserts sqrt sign""" 
    global sqrtChr 
    END = len(calc_entry.get()) 
    equation = calc_entry.get() # takes the whole user's equation from the entry 
    for i in range(-1,-END-1,-1): # loop that goes from -1,-2,-3 to end-1 
     if i == -END: # if there are no exceptions like '.' or special sign, inserts sqrt character at beginning of string in the entry 
      calc_entry.insert(0,sqrtChr) 
     elif equation[i] == '.': # if there is a dot in equation go to next character in equation 
      pass 
     else: 
      try: # if there is a sign insert sqrt character after it and break loop 
       int(equation[i]) 
      except ValueError: 
       calc_entry.insert((END+i+1),sqrtChr) 
       break 

Answer 1

Verwenden

from __future__ import division 

und 1/2 Willen gibt Ihnen 0.5 - die gleiche eval("1/2")