Pass operator to function that selects on dataframe-CodePudding

How to pass operator (eq, ne, gt etc.) to dataframe select function?

import pandas as pd
from operator import eq, ne

df = pd.DataFrame({'Greet Ing': ['Hi Friend', 123, 'Hi Friend', '456']})

df[df['Greet Ing'] == 'Hi Friend']
df.query("`Greet Ing` == 'Hi Friend'")


def filter(dataframe, column, operator, value):
    return dataframe[dataframe[column].operator(value)]

filter(df, 'Greet Ing', eq, 'Hi Friend')  # Not working

The lazy version would be treat operator as string and conditional.

if o == 'eq': ..
elif o == 'ne': ..

CodePudding user response：

Create function with pass Series to operator:

from operator import eq, ne

def f(df1, c, op, y):
    return df1[op(df1[c], y)]

df2 = f(df, 'Greet Ing', eq, 'Hi Friend')
print (df2)
   Greet Ing
0  Hi Friend
2  Hi Friend

Or you can map operator by dictionary:

from operator import eq, ne

ops = {'==': eq, '!=': ne}

def f(df1, c, op, y):
    return df1[ops[op](df1[c], y)]

df2 = f(df, 'Greet Ing', '==', 'Hi Friend')
print (df2)
   Greet Ing
0  Hi Friend
2  Hi Friend