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
Library
Everything you need to level up your coding skills.
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
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
CSV
Turning Currency Strings Into Numbers in a CSV Exactly
Parse $1,234.50, (12.50), 1.234,50 € and 7,00 into exact Decimals, find the cases where stripping symbols is wrong, and spot a column that mixes currencies.
8 min read
CSV
Fixing Mixed Date Formats in a CSV Column Without Guessing
Four formats in one date column, 959 values that are not dates and 15,642 that could be read two ways. Parse with explicit formats and report what you cannot.
9 min read
CSV
Removing Duplicate Rows From a CSV and Choosing the Keeper
Deduplicating a CSV is easy; deciding which duplicate to keep is not. Compare first, last, latest-signup and highest-balance keepers on 200,000 rows.
9 min read
CSV
Trimming Whitespace in Every Field of a CSV Safely
Trim padded CSV fields with pandas, the csv module, DuckDB and qsv, and see why strip() misses the zero-width space that still breaks an email match.
9 min read
Editor's pick
CSVGuide
A Repeatable Way to Clean a Messy CSV File With Python
A cleaning pipeline that never edits the raw file, counts rows at every step and keeps rejects: 200,000 rows in 3.85 s, identical output twice.
25 min read
CSV
Reading a CSV in Swift on macOS and the CRLF Line Trap
Swift has no CSV parser in Foundation, and its String treats CRLF as one Character, so splitting on a newline fails. Parse bytes or use SwiftCSV.
9 min read
CSV
Reading a CSV File in Kotlin for a Quick Import Job
Read a CSV in Kotlin with kotlin-csv and build a small import job that validates rows, rejects bad ones with row numbers and never hides a failure.
11 min read
CSV
Reading CSV Files in Bash Without Breaking on Quotes
A bash read loop on a CSV breaks on quoted commas, backslashes, a missing last newline and empty tab fields. Let a CSV parser emit safe records first.
10 min read
CSV
Parsing CSV in Ruby With the CSV Library and Its Converters
Parse CSV in Ruby 3.4 with the csv gem: the Gemfile LoadError, a numeric converter that read 02134 as 1116, nil versus empty strings, and timings.
10 min read
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