CSV
Making Quick Charts From a CSV With Python and DuckDB
Make quick charts from a large CSV: aggregate in DuckDB, plot with matplotlib or draw text bars in the terminal, and keep the charts honest.
6 min read
Tag
analysis
92 posts
CSV
Checking if a CSV Column Is Normally Distributed With Python
Test whether a CSV column follows a normal distribution using skew, kurtosis, percentiles and Shapiro-Wilk, and why a huge file always fails the test.
7 min read
CSV
Sampling a CSV for a Fast First Look at Large Data
Sample a large CSV for a quick first look: why the top rows mislead, random and reproducible sampling in DuckDB, and how the error shrinks with sample size.
6 min read
CSV
Finding the Top Customers by Revenue in a CSV File
Rank customers by revenue in a CSV with SQL, compute cumulative share and the top 10 percent, handle ties and refunds, and read the concentration curve.
7 min read
CSV
Comparing Two Time Periods in a CSV Without Being Fooled
Compare this month with last month from a CSV in SQL without being fooled by day counts, open periods or weekday mix, using 2 million real rows.
7 min read
CSV
Detecting Seasonality in a CSV of Daily Sales Data
Find weekly and monthly rhythms in daily sales from a CSV: a weekday index, autocorrelation at lag 7, what a flat result looks like and how to adjust for it.
6 min read
CSV
Cross Tabs From a CSV With SQL and a Chi Square Check
Build a cross tab of two CSV columns with DuckDB PIVOT, add row totals and percentages, and test with chi-square whether the two columns are really related.
7 min read
CSVGuide
More Analysis Moves for CSV Data You Can Use Today
Nine analysis moves for a CSV in SQL: cross tabs, period comparisons, concentration, seasonality, distribution shape, sampling, charts and reconciliation.
16 min read
CSV
VisiData for Exploring CSV Interactively in the Terminal
Open a CSV in VisiData to scroll, sort, filter and profile it from the keyboard, build frequency tables, and save results, plus its batch mode for scripts.
7 min read
Excel
Handling Multi Currency Columns in Workbooks and Tables
Handle amounts in several currencies: keep the original amount and code, convert once with a dated rate, never sum mixed currencies and show the rate.
7 min read
Excel
Timesheet Data From Excel Into a Database Without Loss
Load Excel timesheets into a database cleanly: one row per person, day and project, hours as decimals, validation of codes and limits, and approvals kept.
8 min read
Excel
Rounding Rules That Survive Audit in Spreadsheets and SQL
Write a rounding policy an auditor can follow: where to round, which tie rule, per line or per total, and how to test it in Excel, Python and SQL.
7 min read