python有像sumif的函数吗_Python Pandas计数和求和特定条件

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?

解决方案

You can first make a conditional selection, and sum up the results of the selection using the sum function.

>> df = pd.DataFrame({'a': [1, 2, 3]})

>> df[df.a > 1].sum()

a 5

dtype: int64

Having more than one condition:

>> df[(df.a > 1) & (df.a < 3)].sum()

a 2

dtype: int64