A green paper broom clearing loose paper fragments from a spreadsheet.

Data cleanup

Find hidden differences and bring mismatched exports back into order.

Keep a copy of the source, make one change, and compare the result.

A reference card adds one green column to a paper table.

Data cleanup3 min read

Add CSV lookup values and keep unmatched rows

Enrich CSV records from a unique reference key, retain unmatched records, and make missing lookup values visible in Python.

Example files included

Paper ribbons connect reordered table columns.

Data cleanup4 min read

Combine CSV files when columns are in a different order

Append CSV exports by header name with a small Python script that rejects duplicate headers, schema changes, and incomplete rows.

Example files included

Two paper tables with added, removed and changed tiles.

Data cleanup3 min read

Compare CSV snapshots by ID

Compare two keyed CSV snapshots in Python and separate new IDs, missing IDs, and changed field values without relying on row order.

Example files included

Paper records sorted into trays with counting discs.

Data cleanup3 min read

Count CSV records by category and reconcile the total

Build a frequency table from CSV categories in Python, keep blank categories visible, and check that the counts cover every source record.

Example files included

One paper key branches into several matching rows.

Data cleanup3 min read

Explain extra CSV rows after a join by counting keys

Predict join expansion from repeated keys before combining CSV files, and identify which keys create multiple output combinations.

Example files included

Two green columns lift out through a paper export frame.

Data cleanup3 min read

Export only selected CSV columns with an allowlist

Create a smaller CSV using an explicit column allowlist, retain the chosen order, and avoid accidentally carrying extra fields into an export.

Example files included

A paper group label repeats down to a divider.

Data cleanup3 min read

Fill down CSV group labels without crossing boundaries

Carry a group label into following blank cells in Python, stop at an explicit separator row, and reject unlabeled records after the boundary.

Example files included

Paper records pass through two different selection screens.

Data cleanup3 min read

Filter CSV rows with text and numeric conditions

Combine an exact status check with an integer threshold in Python, and keep rejected numeric values separate from ordinary nonmatches.

Example files included

Two paper keys connect matching pairs of table cells.

Data cleanup3 min read

Find CSV duplicates using a two-column key

Check duplicate pairs such as order and line number with tuple keys, without merging distinct records through string concatenation.

Example files included

Paired paper ID tags leave one tag without a match.

Data cleanup3 min read

Find CSV IDs missing from a reference list

Use an exact ID comparison to find records absent from a reference CSV, preserve leading zeros, and keep unmatched rows for review.

Example files included

A green pointer marks a gap between paper stepping stones.

Data cleanup3 min read

Find gaps in an expected CSV number sequence

Check a bounded expected integer sequence against a CSV export, report gaps and duplicates separately, and avoid inferring a range from incomplete data.

Example files included

An inspection strip reveals hidden marks between paper tokens.

Data cleanup3 min read

Find hidden control characters in CSV field values

Report Unicode control characters by record, field, and code point in Python without deleting legitimate tabs or line breaks automatically.

Example files included

Small flags point into missing cells in a paper table.

Data cleanup3 min read

Find missing required values in CSV records

Report blank required fields by record number in Python, treating whitespace as missing while preserving zero as a valid value.

Example files included

A clock and clip select the top record from a paper stack.

Data cleanup3 min read

Keep the latest CSV record per ID using timestamps

Select the newest record for each ID with parsed timestamps, and stop on conflicting records that share the same timestamp.

Example files included

Different paper labels converge on one standard label.

Data cleanup3 min read

Map CSV category aliases without guessing unknown values

Normalize approved category spellings with an explicit mapping, keep original labels, and report values that have no agreed destination.

Example files included

Uneven paper column tabs become uniformly aligned headers.

Data cleanup3 min read

Normalize CSV headers and catch name collisions

Trim and lowercase CSV headers in Python, then reject collisions so two original columns do not collapse into one normalized name.

Example files included

Separate paper glyph pieces align with a complete glyph.

Data cleanup3 min read

Normalize Unicode text before comparing CSV labels

Use Unicode NFC normalization for canonically equivalent text, inspect changed values, and avoid broader replacements that alter identifiers.

Example files included

A tall paper table opens into a wide accordion of columns.

Data cleanup3 min read

Pivot CSV from long to wide without aggregation

Turn period rows into CSV columns in Python, reject duplicate row-and-period pairs, and preserve missing observations as blanks.

Example files included

A paper balance weighs input records against kept and rejected stacks.

Data cleanup3 min read

Reconcile CSV counts after filtering

Account for accepted, filtered, and invalid CSV records in Python so a cleanup step cannot silently lose rows between input and output.

Example files included

Green paper tweezers lift empty row strips from a spreadsheet while populated rows stay in place.

Data cleanup6 min read

Remove blank CSV rows with Python

Remove empty CSV records with Python while preserving quoted line breaks, partial rows, zeros, and spaces. Includes a tested script and sample file.

Example files included

A clip lifts one duplicate card from an ordered row.

Data cleanup3 min read

Remove exact duplicate CSV rows and keep their order

Deduplicate complete CSV records in Python while keeping the first occurrence and distinguishing repeated IDs from truly identical rows.

Example files included

Tweezers remove a spacer between matching paper text strips.

Data cleanup5 min read

Remove invisible spaces that break Excel matches

Clean ordinary and nonbreaking spaces with a targeted formula, inspect character lengths, and avoid merging identifiers that should stay distinct.

Example files included

Extra header bands peel away from the middle of a paper table.

Data cleanup3 min read

Remove repeated header rows from a combined CSV

Identify exact repeated header records inside an export, remove only confirmed header repetitions, and retain a count of affected records.

Example files included

A paper labeling press replaces a column header tag.

Data cleanup3 min read

Rename CSV columns with an explicit mapping

Rename selected CSV headers without moving their values, and reject mappings that would create duplicate output column names.

Example files included

Paper quantity towers rise from smallest to largest.

Data cleanup3 min read

Sort a CSV numeric column without lexicographic mistakes

Sort CSV quantities by parsed integer values while preserving original text and keeping the header outside the sorted data.

Example files included

Grouped paper rows contain descending stacks of quantity beads.

Data cleanup3 min read

Sort CSV rows by category and descending quantity

Use a tuple sort key for mixed ascending and descending CSV ordering, with an explicit tie-breaker for reproducible output.

Example files included

Three tokens in one paper cell become separate record strips.

Data cleanup3 min read

Split a multivalue CSV cell into separate records

Expand a documented pipe-separated list inside one CSV field, keep the parent ID, and report empty list items instead of discarding them.

Example files included

A hinged paper grid turns a highlighted row into a column.

Data cleanup3 min read

Transpose a small CSV without truncating short rows

Swap CSV rows and columns in Python only after checking rectangular shape, then verify that transposing twice recovers the original table.

Example files included

A wide fan of paper columns folds into a long record strip.

Data cleanup3 min read

Unpivot CSV month columns into a long table

Turn selected CSV columns into period-and-value rows in Python while preserving blank observations and repeating the identifier deliberately.

Example files included

Matching paper shapes pass through a selection gate.

Data cleanup3 min read

Validate CSV status values against an allowed list

Check categorical CSV fields against an explicit set, report unexpected spellings, and avoid silently converting new statuses into old ones.

Example files included

Data cleanup

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