Small files. Visible problems.
Try a spreadsheet fix on invented records before touching your own export. Each set links to the guide that explains what to expect.
CSV and TSV files contain plain text. Spreadsheet applications may interpret dates and numbers differently. Keep the original download and follow the linked guide's import steps. Previews read text as UTF-8, so other encodings may show replacement characters. Downloads preserve the original bytes.
Check a separator or find your import problem.
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.
- First export CSV
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id,name,quantity 001,"Blue, large",2 002,White mug,4
First 400 characters at most. Download the file for the complete example.
- Reordered second export CSV
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quantity,id,name 3,003,Green mug 1,004,"Red ""special"" mug"
First 400 characters at most. Download the file for the complete example.
Convert CSV percentage strings to decimal fractions
For a field explicitly formatted as a percentage, remove the trailing percent sign and divide the numeric value by 100. Reject unmarked values unless their scale is documented separately.
- Synthetic CSV sample CSV
Preview file text
rate 12.5% 0% 100%
First 400 characters at most. Download the file for the complete example.
Convert CSV to JSON records without guessing types
Validate the header and row widths, then turn each record into a JSON object. Keep CSV values as strings unless the receiving system gives you an explicit type for each field.
- Synthetic CSV sample CSV
Preview file text
id,quantity,note 0012,3,
First 400 characters at most. Download the file for the complete example.
Convert day/month dates without guessing ambiguous rows
Resolve ambiguous imported dates with an explicit day/month rule, a validation formula, and a downloadable example with invalid-date cases.
- Day/month sample and expected results CSV
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raw_date,declared_order,expected 03/04/2026,DMY,2026-04-03 13/04/2026,DMY,2026-04-13 29/02/2024,DMY,2024-02-29 29/02/2026,DMY,REVIEW 03/04/2026,unknown,REVIEW
First 400 characters at most. Download the file for the complete example.
Count CSV records by category and reconcile the total
Count the category value once per record and keep blank categories as an explicit group. Verify that the category counts sum to the total number of data records.
- Synthetic CSV sample CSV
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id,status A1,ready A2,hold A3,ready A4,
First 400 characters at most. Download the file for the complete example.
CSV opens in one column? Identify the delimiter first
Choose the separator that produces the expected fields, while respecting quoted text.
- Comma-separated example CSV
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product,note,quantity Notebook,"Blue, lined",4 Folder,Archive; keep dry,2
First 400 characters at most. Download the file for the complete example.
- Semicolon-separated example CSV
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product;note;quantity Notebook;Blue, lined;4 Folder;"Archive; keep dry";2
First 400 characters at most. Download the file for the complete example.
- Tab-separated example TSV
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product note quantity Notebook Blue, lined 4 Folder Archive; keep dry 2
First 400 characters at most. Download the file for the complete example.
Detect duplicate CSV headers before values disappear
Read the header as a list and reject duplicate names before using csv.DictReader. Two columns with the same name cannot remain separate values under one dictionary key.
- Synthetic CSV sample CSV
Preview file text
id,city,city A1,Paris,Lyon
First 400 characters at most. Download the file for the complete example.
Export only selected CSV columns with an allowlist
Name the columns you want to keep and write only those fields. An allowlist is easier to review than deleting a few unwanted columns from an export that may later gain new fields.
- Synthetic CSV sample CSV
Preview file text
id,quantity,internal_note P1,2,synthetic note
First 400 characters at most. Download the file for the complete example.
Fill down CSV group labels without crossing boundaries
Carry the last group label forward only within an agreed section. Reset it at a section boundary so a later unlabeled row cannot inherit the previous group accidentally.
- Synthetic CSV sample CSV
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group,id north,A1 ,A2 , ,A3
First 400 characters at most. Download the file for the complete example.
Filter CSV rows with text and numeric conditions
Parse the numeric field explicitly, then combine the conditions using the intended Boolean rule. Report invalid numbers instead of treating them as rows that merely fail the filter.
- Synthetic CSV sample CSV
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id,status,qty A1,ready,12 A2,ready,2 A3,hold,20 A4,ready,many
First 400 characters at most. Download the file for the complete example.
Find CSV duplicates using a two-column key
Use a tuple of the key columns to identify duplicate records. Concatenating values can create collisions between different pairs, even when neither column contains a separator.
- Synthetic CSV sample CSV
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order_id,line,qty 12,3,1 1,23,2 12,3,4
First 400 characters at most. Download the file for the complete example.
Find CSV rows with too many or too few columns
Parse the CSV into lists and compare every record length with the header length. Report mismatches before converting rows to dictionaries, where missing and extra fields are easier to overlook.
- Synthetic CSV sample CSV
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id,name,status A1,Ada,active A2,active A3,Bo,active,extra A4,,active
First 400 characters at most. Download the file for the complete example.
Find gaps in an expected CSV number sequence
Compare the observed sequence numbers with an explicitly expected range. Report duplicates separately, because a duplicate cannot compensate for a missing number.
- Synthetic CSV sample CSV
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sequence 101 102 102 104
First 400 characters at most. Download the file for the complete example.
Find missing required values in CSV records
Check required fields by name and treat an empty or whitespace-only string as missing. Keep the string 0 valid unless the field's business rule says otherwise.
- Synthetic CSV sample CSV
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id,quantity,note A1,0, ,2,check A3,,
First 400 characters at most. Download the file for the complete example.
Fix dates that will not sort in Google Sheets
Inspect the underlying type and convert a known format before sorting the full table.
- Date sorting control records CSV
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record_id,date_text A,2026-10-02 B,2026-02-11 C,2026-01-09 D,2026-12-01
First 400 characters at most. Download the file for the complete example.
Fix decimal commas and thousands separators in Excel
Convert imported numeric text using explicit decimal and grouping marks, preserve blanks, and avoid turning an ambiguous amount into the wrong number.
- Decimal separator examples CSV
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raw_amount,decimal_mark,group_mark,expected "1.234,50",",",.,1234.50 "1,234.50",.,",",1234.50 "-12,75",",",.,-12.75 "1,234",unknown,unknown,REVIEW ,",",.,BLANK
First 400 characters at most. Download the file for the complete example.
Fix garbled accents when importing a CSV into Excel
Match the import encoding to the source bytes before saving a corrected copy.
- UTF-8 without BOM CSV
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city,label Montréal,Café Zürich,Crème
First 400 characters at most. Download the file for the complete example.
- UTF-8 with BOM CSV
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city,label Montréal,Café Zürich,Crème
First 400 characters at most. Download the file for the complete example.
- Windows-1252 example CSV
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city,label Montr�al,Caf� Z�rich,Cr�me
First 400 characters at most. Download the file for the complete example.
Fix numbers stored as text without damaging identifiers
Diagnose numeric-looking text with ISNUMBER, convert quantity cells safely, preserve missing values, and keep identifiers such as 0012 unchanged.
- Numeric text and identifier sample CSV
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raw_value,meaning,expected 12,quantity,12 7,quantity,7 3,quantity,3 0012,identifier,0012 ,missing,BLANK 12 kg,quantity_with_unit,REVIEW
First 400 characters at most. Download the file for the complete example.
Keep leading zeros when importing a CSV into Excel
Set identifier columns to Text during import, before Excel interprets the digits.
- Product IDs with leading zeros CSV
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product_id,product,quantity 00123,Blue notebook,4 00007,Pencil case,12 01230,Desk tray,2 123,Refill pack,8
First 400 characters at most. Download the file for the complete example.
Long numbers in Excel: formatting or lost digits?
Compare the stored identifier with the source before changing its display.
- Long identifier comparison file CSV
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record_id,purpose 123456789012345,15-digit control 1234567890123456,16-digit identifier 1234567890123457,Different final digit 0001234567890123456,Leading zeros and long identifier
First 400 characters at most. Download the file for the complete example.
Map CSV category aliases without guessing unknown values
Use an explicit alias-to-canonical mapping and report unknown labels. Preserve the original value so each change remains explainable.
- Synthetic CSV sample CSV
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id,status A1,in progress A2,working A3,paused
First 400 characters at most. Download the file for the complete example.
Pivot CSV from long to wide without aggregation
Use one field as the row key and another as the column key. Reject duplicate pairs unless an aggregation rule has been explicitly chosen, and keep missing observations distinct from zero.
- Synthetic CSV sample CSV
Preview file text
product,month,value P1,2026-01,2 P1,2026-02,3 P2,2026-01,0
First 400 characters at most. Download the file for the complete example.
Read headerless CSV without losing the first row
Provide field names yourself when the file has no header. Check each row width, then pair its values with the agreed column names. Do not let the first data record become the header.
- Synthetic CSV sample CSV
Preview file text
001,2,ready 002,5,hold
First 400 characters at most. Download the file for the complete example.
Reconcile CSV counts after filtering
Put every source record into exactly one outcome and verify that the outcome counts sum to the input count. Keep invalid data separate from valid records excluded by a filter.
- Synthetic CSV sample CSV
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id,status,qty A1,ready,2 A2,hold,3 A3,ready,bad A4,ready,0
First 400 characters at most. Download the file for the complete example.
Remove blank CSV rows with Python
Parse the CSV before removing rows. Drop empty records and rows whose fields are all empty strings; keep quoted line breaks, partially filled records, zeros, and whitespace.
- Synthetic CSV with empty and multiline records CSV
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id,note , "","" A1,"first line last line" A2, 0, " "," "
First 400 characters at most. Download the file for the complete example.
Remove exact duplicate CSV rows and keep their order
Compare the complete parsed row and keep its first occurrence. Do not deduplicate by identifier alone when two records with the same identifier may contain different values.
- Synthetic CSV sample CSV
Preview file text
id,status A1,ready A1,ready A1,hold A2,ready
First 400 characters at most. Download the file for the complete example.
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.
- Invisible Unicode space sample CSV
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raw_value,expected ACME West ,ACME West ACME West ,ACME West ACME West,ACME West AB CD,AB CD
First 400 characters at most. Download the file for the complete example.
Remove repeated header rows from a combined CSV
Compare each parsed record with the original header and remove exact matches only when the export format confirms they are repeated headings.
- Synthetic CSV sample CSV
Preview file text
id,status A1,ready id,status id,ready A2,hold
First 400 characters at most. Download the file for the complete example.
Rename CSV columns with an explicit mapping
Map old header names to new names, preserve their positions, and check the resulting names for collisions. Renaming a header does not require changing any data value.
- Synthetic CSV sample CSV
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sku,qty P1,2
First 400 characters at most. Download the file for the complete example.
Sort a CSV numeric column without lexicographic mistakes
Convert the sort key to a number, but keep the original record for output. Sorting the original strings puts 10 before 2 because it compares characters rather than quantities.
- Synthetic CSV sample CSV
Preview file text
id,quantity A,10 B,2 C,1
First 400 characters at most. Download the file for the complete example.
Sort CSV rows by category and descending quantity
Build a tuple key in priority order. For an ascending category and descending integer quantity, use the category followed by the negative quantity, then an explicit tie-breaker.
- Synthetic CSV sample CSV
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id,category,qty A2,a,10 B1,b,99 A1,a,10 A3,a,2
First 400 characters at most. Download the file for the complete example.
Split a multivalue CSV cell into separate records
Parse the outer CSV first, then split the selected field using its documented inner separator. Keep the parent identifier on every expanded row and define what empty items mean.
- Synthetic CSV sample CSV
Preview file text
product,tags P1,red|large P2,blue|
First 400 characters at most. Download the file for the complete example.
Sum CSV amounts by group with decimal arithmetic
Parse amounts with Decimal and group by every field that defines a comparable total, including currency. Do not combine different currencies into one unlabeled sum.
- Synthetic CSV sample CSV
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team,currency,amount ops,USD,0.10 ops,USD,0.20 ops,EUR,1.50
First 400 characters at most. Download the file for the complete example.
Transpose a small CSV without truncating short rows
Check that every row has the same width, then transpose the table. A plain zip on ragged rows can truncate values to the shortest row without warning.
- Synthetic CSV sample CSV
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metric,P1,P2 price,2,3 stock,5,7
First 400 characters at most. Download the file for the complete example.
Unpivot CSV month columns into a long table
Keep the identifier columns fixed and emit one output record for each selected value column. Decide explicitly whether blank cells should become blank observations or be omitted.
- Synthetic CSV sample CSV
Preview file text
product,2026-01,2026-02 P1,2,3 P2,0,
First 400 characters at most. Download the file for the complete example.
Validate CSV status values against an allowed list
Compare each value with the documented allowed set and report anything outside it. Keep unexpected values visible until someone decides whether they are errors or new valid categories.
- Synthetic CSV sample CSV
Preview file text
id,status A1,ready A2,Ready A3,paused
First 400 characters at most. Download the file for the complete example.