使用.get集成函数

Question

我正在使用tkinter和scipy制作一个程序，它集成了一个函数，比方说关于x。这是我的代码：

def newtest1():
intwindow = Tk()

Label(intwindow, text = 'enter here', font = ('Symbol')).grid(row=0)
Label(intwindow, text = 'enter upper bound', font = ('Symbol')).grid(row=1)
Label(intwindow, text = 'enter lower bound', font = ('Symbol')).grid(row=2)

get1 = IntVar()
Entry(intwindow, textvariable = get1).grid(row=0, column=1)

getupper = IntVar()
Entry(intwindow, textvariable = getupper).grid(row=1, column=1)

getlower = IntVar()
Entry(intwindow, textvariable = getlower).grid(row=2, column=1)

bty = Button(intwindow, text='click', command = lambda: newfunction()).grid(row=3)

def newfunction():
    x69 = get1.get()
    x_upper = getupper.get()
    x_lower = getlower.get()

    testz = int(x69)
    upperz= int(x_upper)
    lowerz = int(x_lower)



    x9 = lambda x: x69
    res = integrate.quad(x9, x_lower,x_upper)        

    randomwindow = Tk()
    label = Label(randomwindow, text = 'you got {} '.format(round(res[0])))
    label.grid(row=1)

   # Label(randomwindow, text = 'you got %s ' % res).grid(row=1)
    randomwindow.mainloop()



mainloop()
newtest1()

如果您查看函数newfunction（）的内部，就会发现以下代码

    x9 = lambda x: x69
    res = integrate.quad(x9, x_lower,x_upper)

我希望在弹出框中，我可以输入类似于2*x的内容，这样它就会集成。然而，之前我在测试输入框中的数字是否有效时使用了get1=IntVar（）。我试着删除这一点，因为我目前正试图实现，但这会导致一些逻辑错误。为什么我不能在弹出框中输入我自己的x函数，以便python能够集成它

编辑

---

@furas这是我现在使用的代码

import numpy
from numpy import *
import scipy.integrate as integrate
import scipy.special as special
from tkinter import *



def newtest1():
intwindow = Tk()

Label(intwindow, text = 'enter here', font = ('Symbol')).grid(row=0)
Label(intwindow, text = 'enter upper bound', font = ('Symbol')).grid(row=1)
Label(intwindow, text = 'enter lower bound', font = ('Symbol')).grid(row=2)

get1 = StringVar()
Entry(intwindow, textvariable = get1).grid(row=0, column=1)

getupper = IntVar()
Entry(intwindow, textvariable = getupper).grid(row=1, column=1)

getlower = IntVar()
Entry(intwindow, textvariable = getlower).grid(row=2, column=1)

bty = Button(intwindow, text='click', command = lambda: newfunction()).grid(row=3)

def newfunction():
    x69 = get1.get()
    x_upper = getupper.get()
    x_lower = getlower.get()

    #testz = int(x69)
    upperz= int(x_upper)
    lowerz = int(x_lower)



    x9 = eval(f"lambda x: {x69}")
    res = integrate.quad(x9, x_lower,x_upper)        

    randomwindow = Tk()
    label = Label(randomwindow, text = 'you got {} '.format(round(res[0])))
    label.grid(row=1)

   # Label(randomwindow, text = 'you got %s ' % res).grid(row=1)
    randomwindow.mainloop()



mainloop()
newtest1()

这就是我得到的错误

Exception in Tkinter callback
Traceback (most recent call last):
  File "/opt/anaconda3/lib/python3.7/tkinter/__init__.py", line 1705, in __call__
    return self.func(*args)
  File "/Users/isa/Desktop/Diff Eqns/diffeqn.py", line 45, in <lambda>
    bty = Button(intwindow, text='click', command = lambda: newfunction()).grid(row=3)
  File "/Users/isa/Desktop/Diff Eqns/diffeqn.py", line 58, in newfunction
    x9 = eval(lambda x: {x69})
TypeError: eval() arg 1 must be a string, bytes or code object

Answer 1

如果要将字符串"2*x"放在Entry中，则必须使用StringVar()而不是IntVar()来获取它

您需要使用eval()将这个字符串转换为可以计算值的函数

x9 = lambda x: eval(x69)

或者使用f-string或.format()将此字符串放入其他字符串中

x9 = eval(f"lambad x: {x69}")
x9 = eval("lambad x: {}".format(x69)")

在下面的代码中，我使用了名称，它的意思是

function = lambda x: eval(function_str)

---

在代码中，我还添加了其他更改-主要与PEP 8 Style Guide for Python Code相关

import scipy.integrate as integrate
import tkinter as tk # PEP8: `import *` is not preferred

#  - functions  -

def newtest1():

    # - subfunctions -

    def on_button_click(): # PEP8: name of function should means something
        function_str = function_var.get() # PEP8: name of variable should means something
        upper_int = upper_var.get()
        lower_int = lower_var.get()

        function = lambda x: eval(function_str)
        #function = eval(f"lambda x: {function_str}")
        result = integrate.quad(function, lower_int, upper_int)        
        result = round(result[0])

        randomwindow = tk.Toplevel() # second windows should use `Toplevel()` without `mainloop
        label = tk.Label(randomwindow, text=' you got {} '.format(result))
        label.grid(row=1)

        #tk.Label(randomwindow, text=' you got %s ' % result).grid(row=1)

    # - main -

    intwindow = tk.Tk()

    options = {'font': 'Symbol'}
    tk.Label(intwindow, text='enter here', **options).grid(row=0)  # PEP8: without spaces around '='
    tk.Label(intwindow, text='enter upper bound', **options).grid(row=1)
    tk.Label(intwindow, text='enter lower bound', **options).grid(row=2)

    function_var = tk.StringVar() # PEP8: name of variable should means something
    tk.Entry(intwindow, textvariable=function_var).grid(row=0, column=1)

    upper_var = tk.IntVar()
    tk.Entry(intwindow, textvariable=upper_var).grid(row=1, column=1)

    lower_var = tk.IntVar()
    tk.Entry(intwindow, textvariable=lower_var).grid(row=2, column=1)

    tk.Button(intwindow, text='click', command=on_button_click).grid(row=3) # you don't need `lambda` when function created at start

    intwindow.mainloop()

#  - main  -

newtest1()