I want to extract all the decimal numbers from a string, how can I do that?

Question

I made this simple program with functions to calculate mean, median, and mode from a list of numbers. I want to select all the decimal numbers, whatever they are (10.00034, 1, $5.46, $0.90 or 0.5 for example from a string something like "5, 7 83 100, $5.07, and 7.834") from a string and cast them to float. How can I do that in Python 3? I want to capture all decimal numbers with leading zeros as floats including their leading zeros.

import string

def mode(x):
    if len(x) == 0:
        return 0
    else:
        theDictionary = {}
        for number in x:
            count = theDictionary.get(number, None)
            if count == None:
                theDictionary[number] = 1
            else:
                theDictionary[number] = count + 1
        theMaximum = max(theDictionary.values())
        for key in theDictionary:
            if theDictionary[key] == theMaximum:
                print("Mode: ", key)
                return key


def median(x):
    if len(x) == 0:
        return 0
    else:
        x.sort()
        midpoint = len(x) // 2
        print("Median: ", end=" ")
        if len(x) % 2 == 1:
            print(x[midpoint])
            med = x[midpoint]
        else:
            print((x[midpoint] + x[midpoint - 1]) / 2)
            med = (x[midpoint] + x[midpoint - 1]) / 2
        return med


def mean(x):
    if len(x) == 0:
        return 0
    else:
        theSum = 0
        theSum = float(theSum)
        for number in x:
            theSum = theSum + number
        average = theSum / len(x)
        print("Mean: ", average)
        return average


def main():
    lyst = []
    print ("Enter a list of numbers or enter to quit: ")
    numbers = input()
    if numbers == "":
        return 0
    else:
        lyst = numbers.split()
        lyst = [float(x) for x in lyst]
        print("List: ", lyst)
        mode(lyst)
        median(lyst)
        mean(lyst)
        main()

if __name__ == "__main__":
    main()

I tried a few things I found here on stackoverflow and they haven't worked. Any help would be appreciated.