subtracting two columns from pandas dataframe and store the result in third column [closed]

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I have a DataFrame, df, with 3 columns and I want to perform subtraction as follows:

df['available'] = df['recommended'] - df['manual input']

But I am getting an error stating:

unsupported operand type(s) for -: 'int' and 'str'

I have also tried doing

df['available'] = df['recommended'].sub(df['manual input'])

but it shows the same error.

Also I would like to know that does it returns Series if we try to get particular column from dataframe??

回答1:

You have to convert values to numeric - e.g. to integers:

df['available'] = df['recommended'] - df['manual input'].astype(int)

Or to floats:

df['available'] = df['recommended'] - df['manual input'].astype(float)

回答2:

df['available'] = df['recommended'].values - df['manual input'].values

来源：https://stackoverflow.com/questions/48339263/subtracting-two-columns-from-pandas-dataframe-and-store-the-result-in-third-colu