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
Tag
how-to
590 posts
YAML
Limiting Alias Expansion in a YAML Parser Across Languages
Where each parser sets its alias limit: SnakeYAML options, Go's built-in check, Ruby's aliases flag, DuckDB's node budget and a PyYAML guard, all tested.
7 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
JSON
Pretty Printing JSON in Python and From the Terminal
Pretty print JSON with json.dumps(indent), python -m json.tool and pprint, keep non-ASCII readable, sort keys and collapse short arrays.
6 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
Excel
Converting Excel to JSON With Python for Clean Output
Convert an Excel sheet to JSON in Python: records, nested groups and JSON Lines, with typed values, ISO dates, nulls and a check that nothing was lost.
6 min read
CSV
Standardizing Phone Numbers in a CSV File With Python
Normalize phone numbers to E.164 with a regex and the phonenumbers library; the regex accepted 43.8% more numbers than the library calls valid.
8 min read
YAML
Handling YAML Uploads From Users Without Getting Burned
A 40-line guard for accepting YAML uploads: size cap, UTF-8, safe parsing, expanded-size and depth limits, then key checks. Ten test inputs and what each did.
7 min read
CSV
Handling Missing Values in a CSV File Without Guessing
A CSV has no NULL, so missing arrives as empty, a dash, N/A or null. Inventory the tokens, convert to real NA, keep the reason and see what fillna(0) does.
8 min read
Excel
Checking an Excel Upload Before Reading It Into Code
Check an Excel upload before parsing: size, name, zip signature, required parts, macro parts, sheet names and header row, in a fixed order with clear errors.
7 min read