CSV
Checking Row and Column Counts of a CSV Before Loading
How many rows does this CSV have? wc -l, awk, csv, pandas and DuckDB gave 7, 8, 7, an error, 4 and 8 on one small file. Count records and field widths.
10 min read
Topic
CSV
The format everyone exports and nobody specifies. Delimiters, quoting, encodings and loading it into a database intact.
Excel
Converting Excel to Markdown and HTML Tables for Docs
Turn a worksheet into a Markdown or HTML table for documentation with pandas, escape pipes and line breaks, align numbers and keep wide tables readable.
6 min read
CSVGuide
How to Validate a CSV File Before You Trust the Data
Validate a CSV delivery in five layers, bytes, structure, schema, values and keys, with line numbers and exit codes: 193,708 rows checked in about a second.
21 min read
Excel
Converting Excel to SQL Insert Statements Safely and Fast
Turn a worksheet into SQL INSERT statements that quote text, handle NULLs and dates, and load in batches, or skip the script and use COPY or a driver.
6 min read
CSV
Finding Rows That Do Not Match the Expected Pattern in a CSV
Check every column of a CSV against a regex and report failing rows with file line numbers. fullmatch beats match, and 2025-13-45 passes a date pattern.
9 min read
Excel
Converting Excel to Parquet for Faster Analytics Loads
Convert an Excel workbook to Parquet with pandas or DuckDB, fix column types first, write one file per sheet and check counts so analytics loads run fast.
7 min read
CSV
Fixing Numbers With Thousands Separators in a CSV File
A comma inside a number breaks int(), shifts columns when unquoted, and turns European 1.200 into 1.2. Parse strictly, set thousands= and decimal=, and test.
8 min read
CSV
Removing Blank Rows and Stray Footer Lines From a CSV
Report-style exports carry titles, blank lines, repeated headers and Total footers. Find the header, drop what is not data and check the footer's claims.
8 min read
Excel
Converting Excel to YAML Config Files Without Surprises
Turn an Excel sheet of settings or tables into YAML in Python: shape the data, avoid the Norway problem and number traps, dump safely and validate.
7 min read
CSV
Normalizing Capitalization and Spelling in a CSV Column
Collapse USA, usa and United States with a mapping table, use casefold, and treat fuzzy matching as a suggestion: it ranked Australia above Austria.
8 min read
Excel
Converting Excel to XML With a Python Script Safely
Convert an Excel sheet to XML in Python: valid element names, escaping, elements versus attributes, encoding, large files and validation against a schema.
7 min read
CSV
Splitting One CSV Column Into Several Columns With Python
Split names, emails and delimited cells into columns or rows in pandas, handle Last, First, and see why a row-by-row apply ran 40 times slower.
10 min read
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