Lecture 15:- Pandas - Missing Values

In data analysis, dealing with missing values is a common challenge. Pandas provides several methods for handling missing data in DataFrames. Missing values are typically represented by either NaN (Not a Number) or None in Pandas. Here are some common methods to handle missing values in Pandas:

Detecting Missing Values: To identify missing values in a DataFrame, you can use the isnull() or isna() functions, which return a DataFrame of the same shape as the input, where each element is a boolean value representing whether it's a missing value or not.

Output:

Dropping Missing Values: To remove rows containing missing values, you can use the dropna() function. By default, it drops any row that contains at least one missing value.

Filling Missing Values: To replace missing values with a specific value, you can use the fillna() function. It allows you to fill missing values with a constant or use various methods such as forward fill (ffill) or backward fill (bfill).

Imputation with Mean, Median, or Mode: You can use statistical measures like mean, median, or mode to fill missing values in numerical columns.

These methods offer different ways to handle missing values in a DataFrame. The choice of method depends on the specific dataset and the analysis you are conducting. Handling missing data effectively is crucial to obtain accurate insights from your data.

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import pandas as pd # Assuming you have a DataFrame named 'df' df['Age'].fillna(df['Age'].mean(), inplace=True)  # Fills missing values in 'Age' column with mean # Output print(df)

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import pandas as pd # Assuming you have a DataFrame named 'df' df.fillna(value=0, inplace=True)  # Fills missing values with 0 in place # Output print(df)

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import pandas as pd # Assuming you have a DataFrame named 'df' df.dropna(inplace=True)  # Drops rows containing missing values in place # Output print(df)

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      A      B 0  False  False 1  False  False 2   True  False 3  False   True 4  False  False

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import pandas as pd # Create a DataFrame with missing values data = {'A': [1, 2, None, 4, 5],        'B': [10, 20, 30, None, 50]} df = pd.DataFrame(data) # Detect missing values missing_values = df.isnull()  # or df.isna() # Output print(missing_values)