pandas 基于其他其他列创建新列

Question

I have a dataframe called bank and ı would like to create a new column explaining percentage change but when I try ı encounter with this error:unsupported operand type(s) for -: 'str' and 'str' How can I solve this problem or is there other ways for me to create this column?

bank=bank.iloc[0:15,0:4]
pctchange=(bank['Yüksek']-bank['Düşük'])-bank['Düşük']
def risk(bank):
    if pctchange>0.3:
        val='High Risk'
    elif pctchange>0.2 :
        val='Middle Risk'
    else:
        val='Low Risk'
    return val
bank.apply(risk,axis=1)

Answer 1

You could sanitize your data and then try to change type, like this:

# Replace commas with points
bank = bank.apply(lambda x: x.str.replace(',', '.'))

# Convert to float
bank = bank.astype('float64')