The first thing I check before trusting any dataset
Every dataset I've ever received came with a description. Almost none of them matched the data. Not because anyone was lying. The person who wrote t…
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pandas read_csv: Your First DataFrame, and What It Guessed
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can load a CSV into pandas, find out in twenty seconds what…
pandas pct_change and cumsum: Percent Change and Running Totals
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can turn transactions into a monthly series, add period-on-p…
pandas merge: Left Join, Inner Join, and the One That Doubled the Revenue
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can attach columns from one DataFrame to another on a shared…
Handling Missing Values in pandas: dropna, fillna and What Each One Claims
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you can count what is missing and where, choose between dropping…
How to Connect Python to a SQL Database (Straight Into a DataFrame)
By Michael Nocito , data analyst · Published August 8, 2026 By the end of this page you will run a SQL query from Python and get back a pandas DataF…
pandas GroupBy: How to Summarize a DataFrame Without Losing Track of Your Rows
By Michael Nocito , data analyst · Published August 7, 2026 By the end of this page you can take a DataFrame, summarize it by any column or combinat…
How SQL and Python Work Together in Data Analysis
Every data analyst job posting asks for SQL and Python. That raises an honest beginner question nobody seems to answer directly. If both work with d…
One Bug Hit 11 Rows. Another Hit 36 Million.
I built a predictive maintenance model on 37,164,054 telemetry records from an iron ore mine. Six months of alarms from haul trucks and excavators.…
Handling Pandas NaN Values in FastAPI JSON Responses
Handling Pandas NaN Values in FastAPI JSON Responses ===================================================== When building APIs with FastAPI and worki…
Pandas vs Polars: Which One Should You Use in 2025?
Pandas vs Polars: Which One Should You Use in 2025? You’re probably still typing df.groupby() in Pandas while your Polars-using teammate has already…
From Raw Prices to Real Signals: Financial Metrics for a Data Pipeline (Daily Return, MA, RSI, MACD, Volatility)
In this article I will share my understanding and use of some financial metrics used in my Financial Dashboard project. You can see it in this link…
# Turning Data Quality Checks into a Measurable Trust Score
Most data quality problems do not announce themselves loudly. They do not always break a pipeline. They do not always throw an exception. They do no…
Pandas vs SQL, when to use each
Pandas and SQL do a lot of the same things: filter rows, group, aggregate, join. So analysts reasonably ask which to learn and when to use which. Th…
Openpyxl's Relevance for Freelance Data Cleaning and Automation in 2023: Addressing Concerns and Solutions
Introduction: The Question of Relevance Imagine you’re a college student, fresh off mastering pandas , and you’re eyeing the freelancing market for…
Analyzing Steam Games 2025: Genres, Players and User Ratings
As part of my Master in Data Science & AI at Evolve , I worked on a data analysis project using a real Steam games dataset from 2025. The goal o…