Pandas - Fast way of accessing a column of objects' attribute

Question

Let\'s say I have a custom class in python, that has the attribute val. If I have a pandas dataframe with a column of these objects, how can I access this attri

Answer 1

Setup code:

import operator
import random
from dataclasses import dataclass

import numpy as np
import pandas as pd


@dataclass
class SomeObj:
    val: int


df = pd.DataFrame(data={f"col_1": [SomeObj(random.randint(0, 10000)) for _ in range(10000000)]})

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Solution 1

df['col_1'].map(lambda elem: elem.val)

Time: ~3.2 seconds

Solution 2

df['col_1'].map(operator.attrgetter('val'))

Time: ~2.7 seconds

Solution 3

[elem.val for elem in df['col_1']]

Time: ~1.4 seconds

Note: Keep in mind that this solution produces a different result type, which may be an issue in certain situations.

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