PYTHON

joining pandas dataframes

df1 = pd.DataFrame(
    {
        "A": ["A0", "A1", "A2", "A3"],
        "B": ["B0", "B1", "B2", "B3"],
    }
)
df2 = pd.DataFrame(
    {
        "A": ["A4", "A5", "A6", "A7"],
        "B": ["B4", "B5", "B6", "B7"],
    }
)


df3 = pd.DataFrame(
    {
        "A": ["A8", "A9", "A10", "A11"],
        "B": ["B8", "B9", "B10", "B11"],
    }
)
frames = [df1, df2, df3]
result = pd.concat(frames, ignore_index=True)
"""
result = pd.DataFrame(
    {
        "A": ["A0", "A1", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9", "A10", "A11"],
        "B": ["B0", "B1", "B2", "B3", "B4", "B5", "B6", "B7", "B8", "B9", "B10", "B11"],
    },
    index=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
)
"""

join to dataframes pandas

>>> df.join(other.set_index('key'), on='key')
  key   A    B
0  K0  A0   B0
1  K1  A1   B1
2  K2  A2   B2
3  K3  A3  NaN
4  K4  A4  NaN
5  K5  A5  NaN

pandas join dataframe

#https://pandas.pydata.org/docs/user_guide/merging.html