pandas 坏行警告捕获 [英] Pandas Bad Lines Warning Capture

问题描述

熊猫中是否有任何方法可以捕获设置error_bad_lines = False和warn_bad_lines = True所产生的警告?例如以下脚本:

Is there any way in Pandas to capture the warning produced by setting error_bad_lines = False and warn_bad_lines = True? For instance the following script:

import pandas as pd
from StringIO import StringIO
data = StringIO("""a,b,c
                   1,2,3
                   4,5,6
                   6,7,8,9
                   1,2,5
                   3,4,5""")
pd.read_csv(data, warn_bad_lines=True, error_bad_lines=False)

产生警告:

Skipping line 4: expected 3 fields, saw 4

我想将此输出存储为字符串，以便最终将其写入日志文件以跟踪被跳过的记录.

I'd like to store this output to a string so that I can eventually write it to a log file to keep track of records that are being skipped.

我尝试使用警告模块，但这种警告"似乎并不具有传统意义.我正在使用Python 2.7和Pandas 0.16.

I tried using the warning module but it doesn't appear as though this "warning" is of the traditional sense. I'm using Python 2.7 and Pandas 0.16.

任何帮助将不胜感激.

推荐答案

我认为熊猫没有实现它.
source1 ，

I think it isn't implemented to pandas.
source1, source2

我的解决方案:

1.处理之前或之后

import pandas as pd
import csv      

df = pd.read_csv('data.csv', warn_bad_lines=True, error_bad_lines=False)

#compare length of rows by recommended value:
RECOMMENDED = 3

with open('data.csv') as csv_file:
    reader = csv.reader(csv_file, delimiter=',')
    for row in reader:
        if (len(row) != RECOMMENDED):
            print ("Length of row is: %r" % len(row) )
            print row

#compare length of rows by length of columns in df
lencols = len(df.columns)
print lencols

with open('data.csv') as csv_file:
    reader = csv.reader(csv_file, delimiter=',')
    for row in reader:
        if (len(row) != lencols):
            print ("Length of row is: %r" % len(row) )
            print row

2.替换sys.stdout

import pandas as pd
import os
import sys

class RedirectStdStreams(object):
    def __init__(self, stdout=None, stderr=None):
        self._stdout = stdout or sys.stdout
        self._stderr = stderr or sys.stderr

    def __enter__(self):
        self.old_stdout, self.old_stderr = sys.stdout, sys.stderr
        self.old_stdout.flush(); self.old_stderr.flush()
        sys.stdout, sys.stderr = self._stdout, self._stderr

    def __exit__(self, exc_type, exc_value, traceback):
        self._stdout.flush(); self._stderr.flush()
        sys.stdout = self.old_stdout
        sys.stderr = self.old_stderr


if __name__ == '__main__':

    devnull = open('log.txt', 'w')

    #replaces sys.stdout, sys.stderr, see http://stackoverflow.com/a/6796752/2901002
    with RedirectStdStreams(stdout=devnull, stderr=devnull):
        df = pd.read_csv('data.csv', warn_bad_lines=True, error_bad_lines=False)

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