Merge & Join Three pandas DataFrames in Python (Example Code)

import pandas as pd                        # Import pandas library in Python

import pandas as pd # Import pandas library in Python

df1 = pd.DataFrame({"ID":range(1, 6),      # Construct three DataFrames
                    "A":range(111, 116),
                    "B":["a", "x", "ppp", "d", "f"]})
print(df1)
#    ID    A    B
# 0   1  111    a
# 1   2  112    x
# 2   3  113  ppp
# 3   4  114    d
# 4   5  115    f

df1 = pd.DataFrame({"ID":range(1, 6), # Construct three DataFrames "A":range(111, 116), "B":["a", "x", "ppp", "d", "f"]}) print(df1) # ID A B # 0 1 111 a # 1 2 112 x # 2 3 113 ppp # 3 4 114 d # 4 5 115 f

df2 = pd.DataFrame({"ID":range(4, 8),
                    "C":["a", "s", "d", "a"],
                    "D":range(10, 2, - 2)})
print(df2)
#    ID  C   D
# 0   4  a  10
# 1   5  s   8
# 2   6  d   6
# 3   7  a   4

df2 = pd.DataFrame({"ID":range(4, 8), "C":["a", "s", "d", "a"], "D":range(10, 2, - 2)}) print(df2) # ID C D # 0 4 a 10 # 1 5 s 8 # 2 6 d 6 # 3 7 a 4

df3 = pd.DataFrame({"ID":range(2, 10),
                    "E":range(10, 2, - 1)})
print(df3)
#    ID   E
# 0   2  10
# 1   3   9
# 2   4   8
# 3   5   7
# 4   6   6
# 5   7   5
# 6   8   4
# 7   9   3

df3 = pd.DataFrame({"ID":range(2, 10), "E":range(10, 2, - 1)}) print(df3) # ID E # 0 2 10 # 1 3 9 # 2 4 8 # 3 5 7 # 4 6 6 # 5 7 5 # 6 8 4 # 7 9 3

from functools import reduce               # Loading reduce function

from functools import reduce # Loading reduce function

data_merge = reduce(lambda left, right:    # Merge multipl DataFrames
                    pd.merge(left , right,
                             on = ["ID"],
                             how = "outer"),
                    [df1, df2, df3])
print(data_merge)
#    ID      A    B    C     D     E
# 0   1  111.0    a  NaN   NaN   NaN
# 1   2  112.0    x  NaN   NaN  10.0
# 2   3  113.0  ppp  NaN   NaN   9.0
# 3   4  114.0    d    a  10.0   8.0
# 4   5  115.0    f    s   8.0   7.0
# 5   6    NaN  NaN    d   6.0   6.0
# 6   7    NaN  NaN    a   4.0   5.0
# 7   8    NaN  NaN  NaN   NaN   4.0
# 8   9    NaN  NaN  NaN   NaN   3.0

data_merge = reduce(lambda left, right: # Merge multipl DataFrames pd.merge(left , right, on = ["ID"], how = "outer"), [df1, df2, df3]) print(data_merge) # ID A B C D E # 0 1 111.0 a NaN NaN NaN # 1 2 112.0 x NaN NaN 10.0 # 2 3 113.0 ppp NaN NaN 9.0 # 3 4 114.0 d a 10.0 8.0 # 4 5 115.0 f s 8.0 7.0 # 5 6 NaN NaN d 6.0 6.0 # 6 7 NaN NaN a 4.0 5.0 # 7 8 NaN NaN NaN NaN 4.0 # 8 9 NaN NaN NaN NaN 3.0