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CBSE Class 12 Informatics Practices Question 19 of 40

Python Pandas — I — Question 21

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21
Question

Question 15(d)

From the DataFrames created in previous question, write code to add an empty column 'x' to all DataFrames.

Solution
import pandas as pd
d = {'one' : pd.Series([1., 2., 3.], index = ['a', 'b', 'c']), 'two' : pd.Series([1., 2., 3., 4.], index = ['a', 'b', 'c', 'd'])} 
df = pd.DataFrame(d)
df1 = pd.DataFrame(d, index = ['d', 'b', 'a'])
df2 = pd.DataFrame(d, index = ['d', 'a'], columns = ['two', 'three'])
df['x'] = None
df1['x'] = None
df2['x'] = None
print(df)
print(df1)
print(df2)
Output
   one  two     x
a  1.0  1.0  None
b  2.0  2.0  None
c  3.0  3.0  None
d  NaN  4.0  None
   one  two     x
d  NaN  4.0  None
b  2.0  2.0  None
a  1.0  1.0  None
   two three     x
d  4.0   NaN  None
a  1.0   NaN  None
Answer

import
pandas
as
pd
d
=
{
'one'
:
pd
.
Series
([
1.
,
2.
,
3.
],
index
=
[
'a'
,
'b'
,
'c'
]),
'two'
:
pd
.
Series
([
1.
,
2.
,
3.
,
4.
],
index
=
[
'a'
,
'b'
,
'c'
,
'd'
])}
df
=
pd
.
DataFrame
(
d
)
df1
=
pd
.
DataFrame
(
d
,
index
=
[
'd'
,
'b'
,
'a'
])
df2
=
pd
.
DataFrame
(
d
,
index
=
[
'd'
,
'a'
],
columns
=
[
'two'
,
'three'
])
df
[
'x'
]
=
None
df1
[
'x'
]
=
None
df2
[
'x'
]
=
None
print
(
df
)
print
(
df1
)
print
(
df2
)
Output
one two x
a 1.0 1.0 None
b 2.0 2.0 None
c 3.0 3.0 None
d NaN 4.0 None
one two x
d NaN 4.0 None
b 2.0 2.0 None
a 1.0 1.0 None
two three x
d 4.0 NaN None
a 1.0 NaN None