data parsing ai_generated true

CSV parser produces wrong number of fields or corrupted rows with multiline cell values

ID: data/csv-embedded-newlines-break-parser

Also available as: JSON · Markdown
88%Fix Rate
92%Confidence
3Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
any active — — —

Root Cause

RFC 4180 allows newlines inside quoted fields. Naive line-by-line CSV parsing (split on newline, then split on comma) breaks on any cell containing a newline. Python csv module handles this; pandas read_csv does too, but shell tools like awk/cut don't.

generic

Workarounds

  1. 95% success Use a proper CSV parser that handles RFC 4180 (Python csv, pandas) 
    import csv; reader = csv.reader(open('file.csv')); for row in reader: ...  # handles quoted newlines
  2. 88% success Use csvkit for shell-based CSV processing 
    csvcut -c 1,3 file.csv  # properly handles quoting, unlike cut -d, -f1,3
  3. 82% success Pre-validate CSV with csvclean before processing 
    csvclean file.csv  # reports and optionally fixes quoting issues

Dead Ends

Common approaches that don't work:

  1. Read CSV line-by-line and split on commas 95% fail

    Cells containing commas or newlines within quotes break this approach. A single multi-line cell becomes multiple corrupted rows.

  2. Use awk or cut to extract CSV columns 92% fail

    Shell tools don't understand CSV quoting. A quoted comma is treated as a delimiter. A quoted newline splits the row.