How to convert a series of one value to float only?

Use loc

normal_sum.loc[date, 'KWH']

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See @MaxU's answer for at

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Also get_value

normal_sum.get_value(date, 'KWH')

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To return zero when date isn't in the index, you can

normal_sum.KWH.get(date, 0)

if there is only one element in the data series, you could convert it to list by calling tolist() and taking the first element of the new list by referencing [0].