Put restrictions on typing a float variable, a string variable, and leaving blanks of the following interface in Python

good morning.

I am developing a program in Python that I enter the number of students according to their performance in the notes and generate a statistical graph, and would like to know how to put restrictions with graphical interfaces that by typing a decimal number, a variable string and leave blank spaces, show me warning messages saying that this data is not valid.

I could not, only with negative numbers. This would be very helpful, you would be grateful ...

SO I TAKE MY PROGRAM

import tkinter as tk
import sys
from tkinter import font
from tkinter import ttk
from tkinter import messagebox
import math


class Aplicacion:
    def __init__(self):
        # opciones de ventana
        self.ventana1 = tk.Tk()
        self.ventana1.title("Academic statistics")
        self.ventana1.config(bg="gray")
        self.ventana1.geometry("400x330")

        fuente = font.Font(family="roboto", size=10, weight="bold")
        fuentetitulo = font.Font(family="roboto", size=14, weight="bold")
        self.labeltitle = tk.Label(self.ventana1, text="Academic statistics", font=fuentetitulo, bg="#808080",
                                   fg="#FFFFFF")

        self.labeltitle.place(x=110, y=10)

        self.label1 = tk.Label(self.ventana1, text="Students with low notes", font=fuente, bg="#808080")
        self.label1.place(x=20, y=80)
        self.dato1 = tk.StringVar()
        self.entry1 = tk.Entry(self.ventana1, width=20, textvariable=self.dato1)
        self.entry1.place(x=220, y=80)

        self.label2 = tk.Label(self.ventana1, text="Students with middle notes", font=fuente, bg="#808080")
        self.label2.place(x=20, y=120)
        self.dato2 = tk.StringVar()
        self.entry2 = tk.Entry(self.ventana1, width=20, textvariable=self.dato2)
        self.entry2.place(x=220, y=120)

        self.label3 = tk.Label(self.ventana1, text="Students with high notes", font=fuente, bg="#808080")
        self.label3.place(x=20, y=160)
        self.dato3 = tk.StringVar()
        self.entry3 = tk.Entry(self.ventana1, width=20, textvariable=self.dato3)
        self.entry3.place(x=220, y=160)

        self.label4 = tk.Label(self.ventana1, text="Students with top notes", font=fuente, bg="#808080")
        self.label4.place(x=20, y=200)
        self.dato4 = tk.StringVar()
        self.entry4 = tk.Entry(self.ventana1, width=20, textvariable=self.dato4)
        self.entry4.place(x=220, y=200)

        # botones
        self.boton1 = tk.Button(self.ventana1, text="Exit", command=self.finalizar, font=fuente, bg="#DF013A",
                                fg="#FFFFFF")
        self.boton1.place(x=100, y=270)
        self.boton2 = tk.Button(self.ventana1, text="Generar ", font=fuente, bg="#04B431", fg="#FFFFFF",
                                command=self.barras)
        self.boton2.place(x=200, y=270)

        # para hacer visible la ventana
        self.ventana1.resizable(False, False)
        self.ventana1.mainloop()

    # comandos para los botones
    def finalizar(self):
        sys.exit()

    def barras(self):
        valor1 = int(self.dato1.get())
        valor2 = int(self.dato2.get())
        valor3 = int(self.dato3.get())
        valor4 = int(self.dato4.get())
        tot = (valor1 + valor2 + valor3 + valor4)

        if valor1 < 0 or valor2 < 0 or valor3 < 0 or valor4 < 0:
            messagebox.showwarning("Dato Inválido", "Números negativos, por favor ingrese números enteros positivos")
            print("Números negativos, por favor ingrese números enteros positivos")

        else:

            fuente = font.Font(family="roboto", size=10, weight="bold")
            self.ventana2 = tk.Tk()
            self.canvas1 = tk.Canvas(self.ventana2, width=800, height=500, background="gray")
            self.canvas1.grid(column=0, row=0)
            self.canvas1.delete(tk.ALL)

            # if valor1>0 and valor2>0 and valor3>0 and valor4>0 :
            largo1 = (valor1 * 100) / tot
            largo2 = (valor2 * 100) / tot
            largo3 = (valor3 * 100) / tot
            largo4 = (valor4 * 100) / tot

            porc1 = math.floor(largo1)
            porc2 = math.floor(largo2)
            porc3 = math.floor(largo3)
            porc4 = math.floor(largo4)

            self.canvas1.create_rectangle(10, 10, 10 + largo1, 90, fill="orange")
            self.canvas1.create_rectangle(10, 120, 10 + largo2, 200, fill="purple")
            self.canvas1.create_rectangle(10, 230, 10 + largo3, 310, fill="green")
            self.canvas1.create_rectangle(10, 340, 10 + largo4, 420, fill="yellow")

            self.canvas1.create_text(largo1 + 70, 50, text="Middle Notes", fill="white", font=fuente)
            self.canvas1.create_text(largo1 + 300, 50, text=porc1, fill="white", font=fuente)
            self.canvas1.create_text(largo1 + 320, 50, text="%", fill="white", font=fuente)

            self.canvas1.create_text(largo2 + 70, 160, text="Middle Notes", fill="white", font=fuente)
            self.canvas1.create_text(largo2 + 300, 160, text=porc2, fill="white", font=fuente)
            self.canvas1.create_text(largo2 + 320, 160, text="%", fill="white", font=fuente)

            self.canvas1.create_text(largo3 + 70, 270, text="Hight Notes", fill="white", font=fuente)
            self.canvas1.create_text(largo3 + 300, 270, text=porc3, fill="white", font=fuente)
            self.canvas1.create_text(largo3 + 320, 270, text="%", fill="white", font=fuente)

            self.canvas1.create_text(largo4 + 70, 380, text="Top Notes", fill="white", font=fuente)
            self.canvas1.create_text(largo4 + 300, 380, text=porc4, fill="white", font=fuente)
            self.canvas1.create_text(largo4 + 320, 380, text="%", fill="white", font=fuente)

            self.ventana2.mainloop()


# bloque principal
aplicacion1 = Aplicacion()