python add new column to dataframe with same or different length with pandas

Posted on | Edited on

description: add new column to a dataframe

initial data

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a = pandas.DataFrame({'a':[1,2,3]})
# a
#    a
# 0  1
# 1  2
# 2  3
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b = pandas.DataFrame({'b':[2,4,6]})
# b
#    b
# 0  2
# 1  4
# 2  6
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c = pandas.DataFrame({'c':[1,2,3,4,5]})
# c
#    c
# 0  1
# 1  2
# 2  3
# 3  4
# 4  5

concat the same length

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pandas.concat([a,b], axis=1)
#    a  b
# 0  1  2
# 1  2  4
# 2  3  6

concat different length

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pandas.concat([a,c], axis=1)
#      a  c
# 0  1.0  1
# 1  2.0  2
# 2  3.0  3
# 3  NaN  4
# 4  NaN  5