Pandas Preprocessing Cheat Sheet: Essential Methods for Data Analysis

🐼 Pandas Preprocessing Cheat Sheet  A few years ago, I didn't know the difference between .isnull() and .isna() 😅 Now I'm building my own cheat sheets. I've been learning Data preprocessing with Python & Pandas — and honestly, the number of methods felt overwhelming at first. So I did what made sense: I started noting down every method I learned, with a simple example next to it. Over time, that list grew into a full reference sheet — 80+ methods covering: Here's a quick glance at the most important ones: 🔵 Missing Values → df.isnull().sum() — find nulls per column → df.fillna(df['col'].mean()) — fill with mean → df.dropna(subset=['col']) — drop specific nulls 🟢 Data Cleaning → df.drop_duplicates() — remove duplicate rows → df['col'].astype('category') — optimize memory → pd.to_numeric(df['col'], errors='coerce') — safe conversion 🟡 Exploration → df.describe() — instant stats summary → df['col'].value_counts() — frequency of each value → df.corr() — correlation between columns 🔴 Sorting & Filtering → df.sort_values('col', ascending=False) → df.nlargest(5, 'salary') — top 5 rows → df[df['age'] > 30] — filter by condition 🟣 GroupBy & Aggregation → df.groupby('dept')['salary'].mean() → df.pivot_table(values='salary', index='dept') ⚙️ Strings → df['col'].str.strip().str.lower() → df['col'].str.contains('keyword') I've compiled few with examples into a full cheat sheet Save this post for your next data interview! 🔖 #Python #Pandas #DataScience #MachineLearning #DataAnalysis #InterviewPrep #DataEngineering #100DaysOfCode #OpenToWork 👍

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