How I can find out max and min value of each day from hourly data sets

Question

This is hourly data of 2 years and I required max and min of daily data, how can I find this?

                     value
record ts                 
2014-01-01 00:00:00   5.83
2014-01-01 01:00:00   5.38
2014-01-01 02:00:00   4.80
2014-01-01 03:00:00   3.81
2014-01-01 04:00:00   4.46
2014-01-01 05:00:00   5.04
2014-01-01 06:00:00   5.76
2014-01-01 07:00:00   6.15
2014-01-01 08:00:00   6.66
2014-01-01 09:00:00   7.02
2014-01-01 10:00:00   7.43
2014-01-01 11:00:00   7.34
2014-01-01 12:00:00   7.24
2014-01-01 13:00:00   7.71
2014-01-01 14:00:00   8.89
2014-01-01 15:00:00  10.31

Answer 1

You can use resample with Resampler.aggregate min and max:

print (df)
                     value
record ts                 
2014-01-01 00:00:00   5.83
2014-01-01 01:00:00   5.38
2014-01-01 02:00:00   4.80
2014-01-01 03:00:00   3.81
2014-01-02 04:00:00   4.46
2014-01-02 05:00:00   5.04
2014-01-02 06:00:00   5.76
2014-01-03 07:00:00   6.15
2014-01-03 08:00:00   6.66
2014-01-03 09:00:00   7.02
2014-01-03 10:00:00   7.43
2014-01-04 11:00:00   7.34
2014-01-04 12:00:00   7.24
2014-01-04 13:00:00   7.71
2014-01-05 14:00:00   8.89
2014-01-05 15:00:00  10.31

#if not DatetimeIndex
df.index = pd.to_datetime(df.index)
print (df.resample('D')['value'].agg(['min', 'max']))
             min    max
record ts              
2014-01-01  3.81   5.83
2014-01-02  4.46   5.76
2014-01-03  6.15   7.43
2014-01-04  7.24   7.71
2014-01-05  8.89  10.31

Another solution:

print (df.groupby(pd.TimeGrouper('D'))['value'].agg(['min', 'max']))
             min    max
record ts              
2014-01-01  3.81   5.83
2014-01-02  4.46   5.76
2014-01-03  6.15   7.43
2014-01-04  7.24   7.71
2014-01-05  8.89  10.31

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* piRSquared edit, thank you*

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