python加法概率

Question

I've created a python 2.7 tkinter module which uses scale widget data (aquatic or terrestrial) to influence a tuple which selects between animals. The module sorts and displays the three animals (deer, eel, turtles) in ranked descending order upon clicking 'Submit' and activating the associated command.

from Tkinter import (N, S, E, W, BOTH, BOTTOM, END, FLAT, HORIZONTAL, LEFT, NO, RAISED, RIGHT, TOP, YES, Button, Entry, Frame, Grid, Label, Pack, Scale, Text, Tk)

from operator import mul

root = Tk()
root.title('Example')

class Environment:
    def __init__(self, parent):

        # layout
        self.myParent = parent

        self.main_frame = Frame(parent, background="light blue")
        self.main_frame.pack(expand=YES, fill=BOTH)

        self.main_left_frame = Frame(self.main_frame, background="light blue")
        self.main_left_frame.pack(side=LEFT, expand=YES, fill=BOTH)

        self.main_right_frame = Frame(self.main_frame, background="light blue")
        self.main_right_frame.pack(side=RIGHT, expand=YES, fill=BOTH)

        self.water = Scale(self.main_right_frame, from_=0.01, to=1.00, orient=HORIZONTAL, bd=0, label="Aquatic",
        background="white", troughcolor="cyan", length=50, width=10, sliderlength=10, resolution=0.01)
        self.water.pack()
        self.water.set(1.00)

        self.soil = Scale(self.main_right_frame, from_=0.01, to=1.00, orient=HORIZONTAL, bd=0, label="Terrestrial",
        background="white", troughcolor="saddle brown", length=50, width=10, sliderlength=10, resolution=0.01)
        self.soil.pack()
        self.soil.set(1.00)

        self.id_frame = Frame(self.main_left_frame, background="white")
        self.id_frame.pack(side=BOTTOM)

        # submit button
        self.submitbutton = Button(self.main_left_frame,text="Submit", background="black", foreground="white",
        width=6, padx="2m", pady="1m")
        self.submitbutton.pack(side=TOP)
        self.submitbutton.bind("<Button-1>", self.submitbuttonclick)
        self.submitbutton.bind("<Return>", self.submitbuttonclick)

        #Animal Matrix
        self.animal = [
        ('Odocoileous virginiana','White-tailed Deer',self.soil.get,0.99,0.01,0.99),
        ('Anguilla anguilla','American Eel',self.water.get,0.99,0.01,0.99),
        ('Trachemys scripta','Red-eared Slider',lambda:self.soil.get()*self.water.get(),0.99,0.01,0.99)]

    def submitbuttonclick(self, event):
        self.id_frame.destroy()
        self.id_frame = Frame(self.main_left_frame, background="white")
        self.id_frame.pack(side=BOTTOM)

        A=self.animal

        #equation
        sigma = float(sum(reduce(mul,item[3:]) for item in A))
        B = [(item[0], "%.2f" % (item[2]()*reduce(mul, item[3:])/sigma)) for item in A]
        C = sorted(B, key=lambda item: item[1], reverse=True)  

        Label(self.id_frame, text = C[0], background = "white").pack(side=TOP, anchor = W)
        Label(self.id_frame, text = C[1], background = "white").pack(side=TOP, anchor = W)
        Label(self.id_frame, text = C[2], background = "white").pack(side=TOP, anchor = W)

environment = Environment(root)       
root.mainloop()

In theory, sliding the aquatic scale to 0.01 should eliminate the eel (Eel: 0.00) and sliding the terrestrial scale to 0.01 should eliminate the deer (Deer: 0.00). This works fine.

However, when dealing with an animal that is both aquatic and terrestrial, the code falls apart. The turtle should not hit zero so long as either the aquatic or terrestrial scale is above 0.01. Additive probability doesn't work.

lambda:self.soil.get()*self.water.get()

How do I express this so that both are considered but neither can cancel out the other?

Answer 1

Probabilities are funny things. To combine these probabilities you need to look at the probability that it is not terrestial and it is not aquatic. Then take 1 minus that combined probability. The code for the turtle would look like this.

('Trachemys scripta','Red-eared Slider',lambda:1-(1-self.soil.get())*(1-self.water.get()),0.99,0.01,0.99)]