是否有一种直接的方法将CSV文件的内容导入到记录数组中,就像R的read.table(), read.delim()和read.csv()将数据导入到R数据框架中一样?
或者我应该使用csv.reader(),然后应用numpy.core.records.fromrecords()?
是否有一种直接的方法将CSV文件的内容导入到记录数组中,就像R的read.table(), read.delim()和read.csv()将数据导入到R数据框架中一样?
或者我应该使用csv.reader(),然后应用numpy.core.records.fromrecords()?
当前回答
In [329]: %time my_data = genfromtxt('one.csv', delimiter=',')
CPU times: user 19.8 s, sys: 4.58 s, total: 24.4 s
Wall time: 24.4 s
In [330]: %time df = pd.read_csv("one.csv", skiprows=20)
CPU times: user 1.06 s, sys: 312 ms, total: 1.38 s
Wall time: 1.38 s
其他回答
您可以使用此代码将CSV文件数据发送到数组中:
import numpy as np
csv = np.genfromtxt('test.csv', delimiter=",")
print(csv)
可在最新的熊猫和numpy版本。
import pandas as pd
import numpy as np
data = pd.read_csv('data.csv', header=None)
# Discover, visualize, and preprocess data using pandas if needed.
data = data.to_numpy()
我试了一下:
from numpy import genfromtxt
genfromtxt(fname = dest_file, dtype = (<whatever options>))
对比:
import csv
import numpy as np
with open(dest_file,'r') as dest_f:
data_iter = csv.reader(dest_f,
delimiter = delimiter,
quotechar = '"')
data = [data for data in data_iter]
data_array = np.asarray(data, dtype = <whatever options>)
对460万行约70列进行了分析,发现NumPy路径花费了2分16秒,csv-list理解方法花费了13秒。
我会推荐csv-list理解方法,因为它很可能依赖于预编译的库,而不是像NumPy那样依赖解释器。我怀疑pandas方法也有类似的解释器开销。
In [329]: %time my_data = genfromtxt('one.csv', delimiter=',')
CPU times: user 19.8 s, sys: 4.58 s, total: 24.4 s
Wall time: 24.4 s
In [330]: %time df = pd.read_csv("one.csv", skiprows=20)
CPU times: user 1.06 s, sys: 312 ms, total: 1.38 s
Wall time: 1.38 s
我试了一下:
import pandas as p
import numpy as n
closingValue = p.read_csv("<FILENAME>", usecols=[4], dtype=float)
print(closingValue)