python - Pandas :读取列中包含特殊字符的文件

Question

在我拥有的数据中，一些特征值是 ?。如何用 NA 替换它们？

编辑

代码和输出如下:

df = pd.read_csv("cca-census-income.csv", header = None)

df.replace('?', np.nan, inplace=True)

df.ix[0,]

23                Other relative of householder
24                                      1700.09
25                                            ?
26                                            ?
27                                            ?
28             Not in universe under 1 year old
29                                            ?
30                                            0

Answer 1

将参数 na_values='?' 添加到 read_csv .

示例:

import pandas as pd
import io


temp=u"""Date Time,a
2010-01-27 16:00:00,?
2010-01-27 16:10:00,2.2
2010-01-27 16:30:00,1.7"""

df = pd.read_csv(io.StringIO(temp),na_values='?')
print (df)
             Date Time    a
0  2010-01-27 16:00:00  NaN
1  2010-01-27 16:10:00  2.2
2  2010-01-27 16:30:00  1.7

编辑:

谢谢'shivsn'对于建议添加 skipinitialspace=True:

temp=u"""Date Time,a
 ? , ?
? ,?
2010-01-27 16:30:00,1.7"""

df = pd.read_csv(io.StringIO(temp),na_values=['?', '? '], skipinitialspace =True)
print (df)
             Date Time    a
0                  NaN  NaN
1                  NaN  NaN
2  2010-01-27 16:30:00  1.7

按文件编辑 1:

在?之前好像只有空格:

df = pd.read_csv('census-income.data', 
                 header = None, 
                 na_values=['?'], 
                 skipinitialspace =True)
print (df)