Python使用pandas和str.strip崩溃

Question

这个最小的代码崩溃了我的Python.(设置:pandas 0.13.0,python 2.7.3 AMD64,Win7.)

import pandas as pd
input_file = r"c3.csv"
input_df = pd.read_csv(input_file)
for col in input_df.columns:  # strip whitespaces from string values
    if input_df[col].dtype == object:
        input_df[col] = input_df[col].apply(lambda x: x.strip())
print 'start'
for idx in range(len(input_df)):
    input_df['LL'].iloc[idx] = 3
    print idx
print 'finished'

输出:

start
0

Process finished with exit code -1073741819

什么可以防止崩溃:

1. 从c3.csv中删除行.
2. .strip()从代码中删除.
3. 更改c3.csv会for以意外的方式更改迭代次数,直到崩溃.

c3.csv的内容:

 Size    , B/S , Symbol    , Type , BN , Duration , VR , Time    , SR ,LL,
0, xxxx , xxxx0 ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
00, xxxx , xxxxx ,   ,, xxx , 00000 , 00:00:00 , 000000000 , 00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,
0, xxxx , xxxxx ,   ,, xxx , 00000 , 00-00:00:00 , 000000000 , 00-00:00:00 ,

Answer 1

你正在做一个链接的任务,可以以意想不到的方式行事.见这里:http://pandas.pydata.org/pandas-docs/dev/indexing.html#indexing-view-versus-copy.这是在master中修复的,将在0.13.1(即将推出)中工作.见这里:https://github.com/pydata/pandas/pull/6031

这样做不正确:

input_df['LL'].iloc[idx] = 3

相反:

input_df.ix[ix,'LL'] = 3

甚至更好(因为你将所有行分配给3)

input_df['LL'] = 3

如果你只分配一些行(并说一个整数/布尔索引器)

input_df.ix[indexer,'LL'] = 3

您还应该这样做以剥离空白:

input_df[col] = input_df[col].str.strip()