How to get the maximum value of the whole dataframe in pandas

Question

I already sorted the data and the dataframe now is like this:

              Tr Srate(V/ns)mean  Tf Srate(V/ns)mean
CPULabel                                            
100HiBW_Fast                3.16                3.09
100LoBW_Fast                3.16                3.09
BP100_Fast                  3.16                3.06

My dataframe is slew_rate_max. I tried to use:

slew_rate_max.max()

I expected the result to be 3.16. However, I got the max values of both columns individually.

Tr Srate(V/ns)mean    3.16
Tf Srate(V/ns)mean    3.09
dtype: float64

How to get the max value of the whole dataframe not of each column?

Scott Boston · Accepted Answer · 2017-06-22 22:22:40Z

7

Try:

slew_rate_max.max().max()

slew_rate_max.max() returns a series with the max of each column, then taking the max again of that series will give you the max of the entire dataframe.

or

slew_rate_max.values.max()

slew_rate_max.values converts the dataframe to a np.ndarray then using numpy.ndarray.max which as an argument axis that the default is None, this gives the max of the entire ndarray.

edited Jun 22, 2017 at 22:22

answered Jun 22, 2017 at 22:07

Scott Boston

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2 Comments

yash Over a year ago

which one would be faster among these options? doesn't it even matter when there are a million rows?

Scott Boston Over a year ago

@Freak I am pretty sure that slew_rate_max.to_numpy().max() is faster.

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