Converting string in a Pandas data frame to float

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I have the following data frame:

Bestand = pd.DataFrame({'ISIN': ['NaN', 'IE00B4X9L533', 'IE00BF4RFH31'],
                'Marktwert': ['217.803,37', '47.755,10', '15.353,32']})

In order to calculate with the second column named “Marktwert”, I have to convert the string as a float, the sting has German format, that means the decimal point is a comma and the thousands separator is a dot. The number 217.803,37 has the datatype object.

If I try to convert using the code

Bestand['Marktwert'] = pd.to_numeric(Bestand['Marktwert'], downcast="float")

I get the error

ValueError: Unable to parse string "217.803,37" at position 0

Can anyone help me out pls?

Answer

In case you’re reading the data from a file, many of Pandas’ file readers like pandas.read_csv() have decimal and thousands arguments for exactly this case.



Source: stackoverflow