Concatenation in pandas is the process of either adding rows to the end of an existing Series or DataFrame object or adding additional columns to a DataFrame. In pandas, concatenation is performed via the pandas function pd.concat(). The function will perform the operation on a specific axis and as we will see, will also perform any required set logic involved in aligning along that axis.

The general syntax to concatenate data is to pass a list of objects to pd.concat(). The following performs a concatenation of two Series objects:

In [2]:
   # two Series objects to concatenate
   s1 = pd.Series(np.arange(0, 3))
   s2 = pd.Series(np.arange(5, 8))
   s1

Out[2]:
   0    0
   1    1
   2    2
   dtype: int64

In [3]:
   s2

Out[3]:
   0    5
   1    6
   2    7
   dtype: int64

In [4]:
   # concatenate them
   pd.concat([s1, s2])

Out[4]:
   0    0
   1    1
   2    2
   0    5
   1    6
   2    7
   dtype: int64

Two DataFrame objects can also be similarly concatenated.

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