类型错误：float() 参数必须是字符串或数字，而不是“列表”python

Question

I have a problem with Python. This is my code:

def calcola():
            a = input()
            b = float(a[0].split("*"))
            c = float(a[0].split("/")) 
            d = float(a[0].split("-"))
            e = float(a[0].split("+"))
            j = float(a[1].split("*"))
            k = float(a[1].split("/")) 
            l = float(a[1].split("-")) 
            m = float(a[1].split("+")) 
            b = b[0]
            c = b[1]
            d = c[0]
            e = c[1]
            f = d[0]
            g = d[1]
            h = e[0]
            i = e[1]
            somma1 = b+c
            somma2 = d+e
            somma3 = f+g
            somma4 = h+i
            print(somma1)
            print(somma2)
            print(somma3)
            print(somma4)


calcola()

I've recieved some errors:

Traceback (most recent call last): File "file.py", line 29, in calcola() File "file.py", line 3, in calcola b = float(a[0].split("*")) TypeError: float() argument must be a string or a number, not 'list'

How can I transform the number in the list?

Answer 1

You can't call float on a list directly. You can use map to call float on each item in the list. Like so:

b = map(float, a[0].split("*"))

In python 3.x

b = list(map(float, a[0].split("*")))

Or for more readability, use a list comprehension. Works for both python2 and python3:

b = [float(s) for s in a[0].split("*")]

But be sure the items after splitting are floatable