如何解决传递给 builtin_function_or_method.__format__ 的不受支持的格式字符串的问题

Question

I'm trying to do a standardization (z-score normalization)

x = data[['BALANCE', 'BALANCE_FREQUENCY', 'PURCHASES']]

std_scale = preprocessing.StandardScaler().fit(x)
df_std = std_scale.transform(x)

print('Mean after standardization:\nBALANCE={:.2f}, BALANCE_FREQUENCY={:.2f}, PURCHASES={:.2f}'.format(df_std[:,0].mean(), df_std[:,1].mean, df_std[:,2].mean()))

print('\nStandard deviation after standardization:\nBALANCE={:.2f}, BALANCE_FREQUENCY={:.2f}, PURCHASES={:.2f}'.format(df_std[:,0].std(), df_std[:,1].std, df_std[:,2].std()))

and I got this error:

---> 10       .format(df_std[:,0].mean(), df_std[:,1].mean, df_std[:,2].mean()))
    TypeError: unsupported format string passed to builtin_function_or_method.__format__

Answer 1

You are missing parenthesis in your function calls of mean and std .

print('Mean after standardization:\nBALANCE={:.2f}, BALANCE_FREQUENCY={:.2f}, PURCHASES={:.2f}'.format(df_std[:,0].mean(), df_std[:,1].mean(), df_std[:,2].mean()))

print('\nStandard deviation after standardization:\nBALANCE={:.2f}, BALANCE_FREQUENCY={:.2f}, PURCHASES={:.2f}'.format(df_std[:,0].std(), df_std[:,1].std(), df_std[:,2].std()))