# CSVs: how to output missing data to make processing easier?

If supplying data (that can be either string or numeric) via CSVs, what's a good strategy for marking that a value is missing?

• Some non-empty sentinel, like NA
• Some non-empty sentinel, but quoted like "NA"
• The empty string, e.g. in the CSV the value will be 0 characters long.
• The quoted empty string ""
• Something else / depending on case?

If it makes a difference, would like the CSVs to behave reasonably when read using R readr, Python Pandas, and Excel.

If you get to choose, maybe NA (no hyphens) is a sensible default as it's handled as missing value by both libs by default.
• I realise NA is the ISO country code of Namibia, and I am likely to be outputting country codes... – Michal Charemza Jun 7 at 6:16