Union and union all in Pandas dataframe Python:
Union all of two data frames in pandas can be easily achieved by using concat() function. Lets see with an example. First lets create two data frames
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import
pandas as pd
import
numpy as np
#Create a DataFrame
df1
=
{
'Subject'
:[
'semester1'
,
'semester2'
,
'semester3'
,
'semester4'
,
'semester1'
,
'semester2'
,
'semester3'
],
'Score'
:[
62
,
47
,
55
,
74
,
31
,
77
,
85
]}
df2
=
{
'Subject'
:[
'semester1'
,
'semester2'
,
'semester3'
,
'semester4'
],
'Score'
:[
90
,
47
,
85
,
74
]}
df1
=
pd.DataFrame(df1,columns
=
[
'Subject'
,
'Score'
])
df2
=
pd.DataFrame(df2,columns
=
[
'Subject'
,
'Score'
])
df1
df2
|
df1 will be
df2 will be
Union all of dataframes in pandas:
UNION ALL
concat() function in pandas creates the union of two dataframe.
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""" Union all in pandas"""
df_union_all
=
pd.concat([df1, df2])
df_union_all
|
union all of two dataframes df1 and df2 is created with duplicates. So the resultant dataframe will be
Union all of dataframes in pandas and reindex :
concat() function in pandas creates the union of two dataframe with ignore_index = True will reindex the dataframe
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""" Union all with reindex in pandas"""
df_union_all
=
pd.concat([df1, df2],ignore_index
=
True
)
df_union_all
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union all of two dataframes df1 and df2 is created with duplicates and the index is changed. So the resultant dataframe will be
Union of dataframes in pandas:
UNION
ref:http://www.datasciencemadesimple.com/union-and-union-all-in-pandas-dataframe-in-python-2/