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 DataFramedf1 = {
'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'])
df1df2 |
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 |
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/