Pandas series operator as function parameter

Question

Background

I want to perform a calculation on a Pandas Series. This calculation involves min and max. The calculation is used twice. In both cases it is the same calculation except for the min or max functions, which should be different.

I've created a function to perform this calculation:

def my_calc(my_series):
   return my_series.rolling(...).max()

The problem

I don't know how to pass max as a parameter of my_calc.

Attempts

This solution works only for basic operators.
Currently I use my_calc(my_series).max() and my_calc(my_series).min()

what is wrong with my_calc(my_series).max() & my_calc(my_series).min() if my_calc() returns rolling object? — MaxU - stand with Ukraine
– MaxU - stand with Ukraine, Commented Jul 6, 2016 at 12:55

Ignacio Vazquez-Abrams · Accepted Answer · 2016-07-06 12:43:49Z

1

There's really no pretty way to do it.

def my_calc(my_series, func=max):
   if not func in {'min', 'max'}:
      raise ValueError('{} is not a valid method name!'.format(func))
   return getattr(my_series.rolling(...), func)()

foo = my_calc(some_series, 'min')
bar = my_calc(some_series, 'max')

answered Jul 6, 2016 at 12:43

Ignacio Vazquez-Abrams

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Comments

DeepSpace · Accepted Answer · 2016-07-06 12:46:56Z

1

Call my_calc with the name of the function as string, then use getattr:

def my_calc(my_series, func_name):
    try:
        return getattr(my_series.rolling(...), func_name)()
    except AttributeError:
        print('{} has no attribute {}'.format(type(my_series), func_name))

my_calc(my_series, 'min')

answered Jul 6, 2016 at 12:46

DeepSpace

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Comments

Ankanna · Accepted Answer · 2016-07-06 12:47:18Z

1

Try like this rolling_max

def my_calc(my_series):
  return my_series.rolling_max(...)

answered Jul 6, 2016 at 12:47

Ankanna

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1 Comment

Michael Over a year ago

FutureWarning: pd.rolling_min is deprecated for Series and will be removed in a future version, replace with  	Series.rolling(window=4320,center=False).min()

user2285236 · Accepted Answer · 2016-07-06 12:54:28Z

1

You can use apply (or agg):

def my_calc(my_series, func):
   return my_series.rolling(...).apply(func)

And use like:

my_calc(ser, np.mean)
Out[321]: 
0    NaN
1    0.5
2    0.0
3    0.5
4    2.0
Name: a, dtype: float64

answered Jul 6, 2016 at 12:54

user2285236

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Pandas series operator as function parameter

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