python - 使用 Python 和 Pandas 修剪 CSV 中的列

Question

我有一个包含多列的 csv 文件，我只需要两个标题为“地址”和“端口”的文件。我正在使用 Panda 尝试这个简单的函数，但出现错误。知道问题是什么吗？谢谢。

输入文件包含带有标题的列:开始时间、结束时间、地址、供应商、主机名、端口、状态、服务、脚本、输出

import pandas as pd
def trim_scan(infile, outdir):

    df = pd.read_csv(infile)
    keep_cols = ["address", "port"]
    new_df = df[keep_cols]
    new_df.to_csv(outdir + '/' + 'nmap-ip-ports.csv', index=False)

trim_scan('nmap-scan.csv', '2015-07-27')

这是错误:

Traceback (most recent call last):
  File "test3.py", line 64, in <module>
    trim_scan('nmap-scan.csv', '2015-07-27')
  File "test3.py", line 59, in trim_scan
    df = pd.read_csv(infile)
  File "/Library/Python/2.7/site-packages/pandas/io/parsers.py", line 474, in parser_f
    return _read(filepath_or_buffer, kwds)
  File "/Library/Python/2.7/site-packages/pandas/io/parsers.py", line 260, in _read
    return parser.read()
  File "/Library/Python/2.7/site-packages/pandas/io/parsers.py", line 721, in read
    ret = self._engine.read(nrows)
  File "/Library/Python/2.7/site-packages/pandas/io/parsers.py", line 1170, in read
    data = self._reader.read(nrows)
  File "pandas/parser.pyx", line 769, in pandas.parser.TextReader.read (pandas/parser.c:7544)
  File "pandas/parser.pyx", line 791, in pandas.parser.TextReader._read_low_memory (pandas/parser.c:7784)
  File "pandas/parser.pyx", line 844, in pandas.parser.TextReader._read_rows (pandas/parser.c:8401)
  File "pandas/parser.pyx", line 831, in pandas.parser.TextReader._tokenize_rows (pandas/parser.c:8275)
  File "pandas/parser.pyx", line 1742, in pandas.parser.raise_parser_error (pandas/parser.c:20691)
pandas.parser.CParserError: Error tokenizing data. C error: Expected 12 fields in line 6, saw 14

Answer 1

问题来自于您的 CSV 文件，该文件不规则(每行的字段数量不同)。

Expected 12 fields in line 6, saw 14

关于您的 CSV 文件格式不正确的另一个提示是您定义了 10 个不同的字段:

Start Time, End time, address, vendor, hostname, port, state, service, script, output

但是 pandas 期望 12。

您可以检查时间戳的格式或值中包含 ; 的任何其他字段。检查标题、跳过坏行等。