Error: ValueError: invalid fill method
Explanation: This error occurs when using the fillna() method in pandas with an invalid fill method.
Valid fill methods for the fillna() method are pad (ffill) and backfill (bfill).
If the provided fill method is set to linear, this error will be raised, as it is not a valid fill method.
Example:
# Importing pandas library
import pandas as pd
# Creating a sample dataframe
data = {'A': [1, 2, 3, 4, 5],
'B': [10, 20, 30, 40, 50],
'C': [100, 200, 300, 400, 500]}
df = pd.DataFrame(data)
# Trying to fill missing values with an invalid fill method
df.fillna(method='linear') # Raises ValueError
In the above example, when trying to fill missing values using the linear fill method, the ValueError will be raised as it is not a valid fill method. Valid fill methods for fillna() are pad (ffill) and backfill (bfill).