[python] Python Pandas counting and summing specific conditions

Are there single functions in pandas to perform the equivalents of SUMIF, which sums over a specific condition and COUNTIF, which counts values of specific conditions from Excel?

I know that there are many multiple step functions that can be used for

for example for sumif I can use (df.map(lambda x: condition), or df.size()) then use .sum()

and for countif I can use (groupby functions and look for my answer or use a filter and the .count())

Is there simple one step process to do these functions where you enter the condition and the data frame and you get the sum or counted results?

You didn't mention the fancy indexing capabilities of dataframes, e.g.:

>>> df = pd.DataFrame({"class":[1,1,1,2,2], "value":[1,2,3,4,5]})
>>> df[df["class"]==1].sum()
class    3
value    6
dtype: int64
>>> df[df["class"]==1].sum()["value"]
6
>>> df[df["class"]==1].count()["value"]
3

You could replace df["class"]==1by another condition.

I usually use numpy sum over the logical condition column:

>>> import numpy as np
>>> import pandas as pd
>>> df = pd.DataFrame({'Age' : [20,24,18,5,78]})
>>> np.sum(df['Age'] > 20)
2

This seems to me slightly shorter than the solution presented above