Cannot concatenate object of type ‘‘; only series and dataframe objs are valid

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Explanation:

The error message you mentioned occurs when trying to concatenate a numpy array with another object that is not a pandas Series or DataFrame.

To better understand this error, let’s dive into an example.

Example:


import numpy as np
import pandas as pd

# Create a numpy array
arr = np.array([1, 2, 3])

# Try to concatenate the array with an invalid object
concatenated = pd.concat([arr, pd.Series([4, 5, 6])])

# The error occurs here, since arr is a numpy array and not a pandas Series or DataFrame

# Correct way to concatenate using only pandas objects
s = pd.Series([1, 2, 3])
concatenated = pd.concat([s, pd.Series([4, 5, 6])])

# Output:
# 0    1
# 1    2
# 2    3
# 0    4
# 1    5
# 2    6
# dtype: int64

In the above example, we first create a numpy array ‘arr’. Then we attempt to concatenate ‘arr’ with a pandas Series. However, this throws an error because concatenation with numpy arrays is not supported.

The correct way to concatenate using the pandas.concat() function is by providing only pandas Series or DataFrame objects as arguments. In the corrected example, we create a pandas Series ‘s’ instead of a numpy array ‘arr’ and successfully concatenate it with another Series.

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