array([[row1], [row2], ..., [rowN]])
所以我们可以
ravel
应该很快。
df[['data1', 'data2']].to_numpy().ravel().tolist()
#[20, 120, 30, 456, 40, 34]
import perfplot
import pandas as pd
import numpy as np
from itertools import chain
perfplot.show(
setup=lambda n: pd.DataFrame(np.random.randint(1, 10, (n, 2))),
kernels=[
lambda df: df[[0, 1]].to_numpy().ravel().tolist(),
lambda df: [x for i in zip(df[0], df[1]) for x in i],
lambda df: [*chain.from_iterable(df[[0,1]].to_numpy())],
lambda df: df[[0,1]].stack().tolist() # proposed by @anky_91
],
labels=['ravel', 'zip', 'chain', 'stack'],
n_range=[2 ** k for k in range(20)],
equality_check=np.allclose,
xlabel="len(df)"
)