Question

我想通过根据特定列中的值选择行来限制要打印的行。

例如：

Column1, Column2, Column3
aaa, bbb, ccc
none, ddd, ggg

我只想打印Column1值为none的行。

这是我的代码：

for v in df:
    if 'none' in df['2nd_prize']:
        print v

Answer 1

for row in table:
  if row[0] is none:
    print row

Answer 2

您可以使用loc对数据框的行进行子集，以限制"none"中包含Column 1的行，如下所示：

数据准备

In [1]: import pandas as pd
   ...: from io import StringIO
   ...: 

In [2]: df = pd.read_csv(StringIO(
   ...: '''
   ...: Column1, Column2, Column3
   ...: aaa, bbb, ccc
   ...: none, ddd, ggg
   ...: kkk, jjj, ppp
   ...: none, eee, fff
   ...: '''))

<强>运营

In [3]: df.loc[df['Column1'] == "none"]
Out[3]: 
  Column1  Column2  Column3
1    none      ddd      ggg
3    none      eee      fff

Answer 3

您可以使用带掩码的boolean indexing：

import pandas as pd

df = pd.DataFrame({'Column2': {0: 'bbb', 1: 'ddd'}, 
                   'Column1': {0: 'aaa', 1: 'none'}, 
                   'Column3': {0: 'ccc', 1: 'ggg'}})

print (df)
  Column1 Column2 Column3
0     aaa     bbb     ccc
1    none     ddd     ggg

print (df['Column1'] == "none")
0    False
1     True
Name: Column1, dtype: bool

print (df[df['Column1'] == "none"])
  Column1 Column2 Column3
1    none     ddd     ggg

如果值包含字符串开头的空格，请使用str.strip：

import pandas as pd

df = pd.DataFrame({'Column2': {0: ' bbb', 1: ' ddd'}, 
                   'Column1': {0: ' aaa', 1: ' none'}, 
                   'Column3': {0: ' ccc', 1: ' ggg'}})

print (df)
  Column1 Column2 Column3
0     aaa     bbb     ccc
1    none     ddd     ggg

print (df['Column1'].str.strip() == "none")
0    False
1     True
Name: Column1, dtype: bool

print (df[df['Column1'].str.strip() == "none"])
  Column1 Column2 Column3
1    none     ddd     ggg

Answer 4

这是另一种方法，首先手动删除空白，然后将处理过的文件内容提供给pandas。

import pandas as pd
from io import StringIO

# First strip out the whitespace
contents = open('Input.txt').read().splitlines()
contents = "\n".join([",".join([x.strip() for x in y.split(",")]) for y in contents])

# Convert to a stringIO to feed to pandas
df = pd.read_csv(StringIO(unicode(contents, 'utf-8')))

print df[df['Column1'] == "none"]

Pandas - 根据一列中的值打印限制行

4 个答案: