Typeerror: cannot concatenate object of type ‘‘; only series and dataframe objs are valid

The error “TypeError: cannot concatenate object of type ‘‘; only series and dataframe objects are valid” occurs when you are trying to concatenate or combine two numpy ndarrays, which is not allowed. Concatenation is only valid for Pandas Series and DataFrames.

To illustrate this, consider the following example:

    
      import numpy as np

      # Create two numpy ndarrays
      arr1 = np.array([1, 2, 3])
      arr2 = np.array([4, 5, 6])

      # Try to concatenate the ndarrays
      result = np.concatenate((arr1, arr2))
    
  

In the above example, we have two numpy ndarrays, `arr1` and `arr2`. However, when we try to concatenate them using the `np.concatenate()` function, we encounter the “TypeError: cannot concatenate object of type ‘‘; only series and dataframe objects are valid” error message.

To resolve this issue, you should convert the ndarrays into Pandas Series or DataFrames before concatenation. Here’s an example of how you can do that:

    
      import numpy as np
      import pandas as pd

      # Create two numpy ndarrays
      arr1 = np.array([1, 2, 3])
      arr2 = np.array([4, 5, 6])

      # Convert ndarrays to pandas series
      series1 = pd.Series(arr1)
      series2 = pd.Series(arr2)

      # Concatenate the series
      result = pd.concat([series1, series2])
    
  

In this updated example, we first convert `arr1` and `arr2` into Pandas Series using the `pd.Series()` function. Then, we can use the `pd.concat()` function to concatenate the series without any errors.