动机
许多数据集足够大,我们需要关注速度/效率。因此,我本着这种精神提供了这个解决方案。它恰好也很简洁。
为了比较,让我们删除index
列
df = data_set.drop('index', 1)
解决方案
我建议使用zip
andmap
list(zip(*map(df.get, df)))
[('2012-02-17', 24.75, 25.03),
('2012-02-16', 25.0, 25.07),
('2012-02-15', 24.99, 25.15),
('2012-02-14', 24.68, 25.05),
('2012-02-13', 24.62, 24.77),
('2012-02-10', 24.38, 24.61)]
如果我们想处理特定的列子集,它也很灵活。我们假设我们已经显示的列是我们想要的子集。
list(zip(*map(df.get, ['data_date', 'data_1', 'data_2'])))
[('2012-02-17', 24.75, 25.03),
('2012-02-16', 25.0, 25.07),
('2012-02-15', 24.99, 25.15),
('2012-02-14', 24.68, 25.05),
('2012-02-13', 24.62, 24.77),
('2012-02-10', 24.38, 24.61)]
什么是更快?
Turn's outrecords
是最快的,其次是渐近收敛zipmap
和iter_tuples
我将使用simple_benchmarks
从这篇文章中获得的库
from simple_benchmark import BenchmarkBuilder
b = BenchmarkBuilder()
import pandas as pd
import numpy as np
def tuple_comp(df): return [tuple(x) for x in df.to_numpy()]
def iter_namedtuples(df): return list(df.itertuples(index=False))
def iter_tuples(df): return list(df.itertuples(index=False, name=None))
def records(df): return df.to_records(index=False).tolist()
def zipmap(df): return list(zip(*map(df.get, df)))
funcs = [tuple_comp, iter_namedtuples, iter_tuples, records, zipmap]
for func in funcs:
b.add_function()(func)
def creator(n):
return pd.DataFrame({"A": random.randint(n, size=n), "B": random.randint(n, size=n)})
@b.add_arguments('Rows in DataFrame')
def argument_provider():
for n in (10 ** (np.arange(4, 11) / 2)).astype(int):
yield n, creator(n)
r = b.run()
检查结果
r.to_pandas_dataframe().pipe(lambda d: d.div(d.min(1), 0))
tuple_comp iter_namedtuples iter_tuples records zipmap
100 2.905662 6.626308 3.450741 1.469471 1.000000
316 4.612692 4.814433 2.375874 1.096352 1.000000
1000 6.513121 4.106426 1.958293 1.000000 1.316303
3162 8.446138 4.082161 1.808339 1.000000 1.533605
10000 8.424483 3.621461 1.651831 1.000000 1.558592
31622 7.813803 3.386592 1.586483 1.000000 1.515478
100000 7.050572 3.162426 1.499977 1.000000 1.480131
r.plot()