I have a python code and a json file, I can't change the string to float

Question

Python Code:

import json

bankstatementjson = open('bankstatement_sept_20.json', 'r')
bankstatement = bankstatementjson.read()

bankstm = json.loads(bankstatement)

for x in bankstm:
    konto_ut = (x["FIELD7"])
    print(float(konto_ut))

for i in bankstm:
    konto_inn = (i["FIELD8"])
    print(float(konto_inn))

Json Data

    {
      "FIELD1": "2020-09-01",
      "FIELD2": "2020-09-02",
      "FIELD3": "50001685147",
      "UTGÅENDE SALDO": "NO1300000000000",
      "9759,52": "Visa",
      "FIELD6": "*9808 31.08 Nok 22.00 Extra Bislett Kurs: 1.0000",
      "FIELD7": "22,00",
      "FIELD8": ""
    },

Error:

ValueError: could not convert string to float: ''

Answer 1

For the one with a comma, it should be changed to a . which is the standard for decimal points in Python:

konto_ut = x["FIELD7"].replace(",", ".")
print(float(konto_ut)) # 22.0

For empty strings, you can check if it's empty before printing as a float:

konto_inn = i["FIELD8"]
print(float(konto_inn) if (konto_inn != "") else 0) # 0

Another option would be to catch the exception which will avoid other potential issues with float conversions:

def is_number(s):
    try:
        float(s)
        return True
    except ValueError:
        return False

konto_inn = i["FIELD8"]
if (is_number(konto_inn):
    print(float(konto_inn))
else:
    print("Not a number")