A 30-Day Prep Checklist That Actually Works
Python has become the core skill for Data Analyst and Data Scientist roles.
Yet, many candidates fail interviews not because they don’t know Python, but because they don’t prepare the right way.
This article breaks down a 30-day, practical Python interview prep checklist focused specifically on Data Analyst / Data Science roles — not generic software engineering.
🔍 What Interviewers Really Test in Python (Data Roles)
Before the checklist, let’s clarify what companies usually look for:
✔ Data manipulation skills
✔ Ability to clean messy datasets
✔ Logical thinking using Python
✔ Strong Pandas & NumPy foundations
✔ Clear explanation of approach (not just code)
📅 Week 1: Python Fundamentals (Days 1–7)
Focus: Logic + Core Language Confidence
🔹 Data types (list, tuple, set, dict)
🔹 Loops & conditional logic
🔹 Functions & lambda expressions
🔹 List & dictionary comprehensions
🔹 is vs ==, mutability concepts
🔹 Exception handling
🎯 Interview expectation:
Can you write clean, readable Python logic without overcomplicating it?
✅ Practice tasks:
Reverse strings & lists
Frequency count using dictionaries
Simple data transformations
📅 Week 2: Pandas Deep Dive (Days 8–14)
Focus: Real-World Data Handling
🔹 Creating DataFrames & Series
🔹 Reading CSV, Excel, JSON files
🔹 Indexing & filtering data
🔹 groupby, agg, apply
🔹 Sorting & ranking
🔹 Merging & joining datasets
🎯 Interview expectation:
Can you answer business questions using Pandas?
✅ Practice tasks:
Find top-performing categories
Calculate averages per group
Merge sales and customer data
📅 Week 3: Data Cleaning & NumPy (Days 15–21)
Focus: Messy Data = Real Interviews
🔹 Handling missing values (`NaN`)
🔹 Data type conversions
🔹 Outlier detection
🔹 String operations
🔹 NumPy arrays & vectorization
🔹 Performance comparison (loops vs vectorized ops)
🎯 Interview expectation:
How do you clean and prepare raw data for analysis?
✅ Practice tasks:
Fill or drop missing values with logic
Normalize numerical columns
Clean text columns (trim, lower, replace)
📅 Week 4: Interview-Style Problems & SQL Integration (Days 22–30)
Focus: Confidence Under Pressure
🔹 Pandas-based case studies
🔹 SQL + Python logic (joins, filters)
🔹 Writing efficient solutions
🔹 Explaining your thought process
🔹 Mock interviews & timed practice
🎯 Interview expectation:
Can you explain why you chose a solution?
✅ Practice tasks:
Convert SQL queries into Pandas
Solve Kaggle-style datasets
Practice explaining code out loud
🧠 Most Asked Python Interview Topics (Data Roles)
✔ Pandas groupby use cases
✔ Handling missing values
✔ Difference between apply, map, vectorization
✔ Performance optimization
✔ DataFrame vs NumPy array
✔ Real-world data cleaning strategies
🚫 Common Mistakes Candidates Make
❌ Memorizing syntax without practice
❌ Ignoring data cleaning questions
❌ Writing complex one-liners without clarity
❌ Not explaining the approach
❌ Avoiding mock interviews
🎯 Final Advice
Python interviews for Data Analysts are less about clever tricks and more about:
Clarity, correctness, and confidence with data.
If you can clean data, analyze it logically, and explain your thinking, you’re already ahead of most candidates.
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