在pandas.DataFrame.to_csv中编写多个标题行

Question

我将我的数据放入NASA的ICARTT格式进行存档.这是一个逗号分隔的文件,有多个标题行,标题行中有逗号.就像是:

46, 1001
lastname, firstname
location
instrument
field mission
1, 1
2011, 06, 21, 2012, 02, 29
0
Start_UTC, seconds, number_of_seconds_from_0000_UTC
14
1, 1
-999, -999
measurement name, units
measurement name, units
column1 label, column2 label, column3 label, column4 label, etc.

我必须为收集数据的每一天制作一个单独的文件,因此我最终将创建大约30个文件.当我通过pandas.DataFrame.to_csv创建一个csv文件时,我不能(据我所知)在写入数据之前简单地将标题行写入文件,所以我不得不欺骗它来做我想做的事情

# assuming <df> is a pandas dataframe
df.to_csv('dst.ict',na_rep='-999',header=True,index=True,index_label=header_lines)

其中"header_lines"是标题字符串

这给我的正是我想要的,除了"header_lines"被双引号括起来.有没有办法使用to_csv将文本写入csv文件的头部或删除双引号？我已经尝试在to_csv()中设置quotechar =''和doublequote = False,但双引号仍然出现.

我现在正在做什么(它现在有效,但我想转向更好的东西)只是通过打开('dst.ict','w')打开一个文件并逐行打印到该行,这是很慢.

Answer 1

实际上,您可以在数据之前编写标题行.pandas.DataFrame.to_csv将a path_or_buf作为其第一个参数,而不仅仅是路径名:

pandas.DataFrame.to_csv(path_or_buf, *args, **kwargs)

• path_or_buf :字符串或文件句柄,默认为None

  文件路径或对象,如果提供"无",则结果将作为字符串返回.

这是一个例子:

#!/usr/bin/python2

import pandas as pd
import numpy as np
import sys

# Make an example data frame.
df = pd.DataFrame(np.random.randint(100, size=(5,5)),
                  columns=['a', 'b', 'c', 'd', 'e'])

header = '\n'.join(
    # I like to make sure the header lines are at least utf8-encoded.
    [unicode(line, 'utf8') for line in 
        [ '1001',
        'Daedalus, Stephen',
        'Dublin, Ireland',
        'Keys',
        'MINOS',
        '1,1',
        '1904,06,16,1922,02,02',
        'time_since_8am', # Ends up being the header name for the index.
        ]
    ]
)

with open(sys.argv[1], 'w') as ict:
    # Write the header lines, including the index variable for
    # the last one if you're letting Pandas produce that for you.
    # (see above).
    for line in header:
        ict.write(line)

    # Just write the data frame to the file object instead of
    # to a filename. Pandas will do the right thing and realize
    # it's already been opened.
    df.to_csv(ict)

结果就是你想要的 - 编写标题行,然后调用.to_csv()和写入:

$ python example.py test && cat test
1001
Daedalus, Stephen
Dublin, Ireland
Keys to the tower
MINOS
1, 1
1904, 06, 16, 1922, 02, 02
time_since_8am,a,b,c,d,e
0,67,85,66,18,32
1,47,4,41,82,84
2,24,50,39,53,13
3,49,24,17,12,61
4,91,5,69,2,18

对不起,如果这太晚了,无法使用.我正在处理这些文件的归档(并使用Python),所以如果你有未来的问题,请随时给我留言.