更新时间:2023-02-27 10:41:42
是的,读取 csv
numpy
很慢。沿着代码路径有很多纯Python。这些天,即使我使用纯 numpy
,我仍然使用 pandas
作为IO:
Yeah, reading csv
files into numpy
is pretty slow. There's a lot of pure Python along the code path. These days, even when I'm using pure numpy
I still use pandas
for IO:
>>> import numpy as np, pandas as pd
>>> %time d = np.genfromtxt("./test.csv", delimiter=",")
CPU times: user 14.5 s, sys: 396 ms, total: 14.9 s
Wall time: 14.9 s
>>> %time d = np.loadtxt("./test.csv", delimiter=",")
CPU times: user 25.7 s, sys: 28 ms, total: 25.8 s
Wall time: 25.8 s
>>> %time d = pd.read_csv("./test.csv", delimiter=",").values
CPU times: user 740 ms, sys: 36 ms, total: 776 ms
Wall time: 780 ms
或者,在像这样简单的情况下,你可以使用像Joe Kington在这里写道:
Alternatively, in a simple enough case like this one, you could use something like what Joe Kington wrote here:
>>> %time data = iter_loadtxt("test.csv")
CPU times: user 2.84 s, sys: 24 ms, total: 2.86 s
Wall time: 2.86 s
还有Warren Weckesser的 textreader 库, pandas $ c>是太重的依赖:
There's also Warren Weckesser's textreader library, in case pandas
is too heavy a dependency:
>>> import textreader
>>> %time d = textreader.readrows("test.csv", float, ",")
readrows: numrows = 1500000
CPU times: user 1.3 s, sys: 40 ms, total: 1.34 s
Wall time: 1.34 s