# Importing daily data: '-1' in volume column

I am working on importing some daily data from a public data source as csv format.

The csv convention of the file seems to be that if data is not available for a field, a single white space is used as NaN placeholder.

Now however, I have encountered a single row where the volume field contains -1. To me, the volume by definition has to be a positive number. - Or are there situation where a negative volume can occur?

• What is the public data source? When did you get the data? Was it updated since then? What does the source say? – SRKX Dec 12 '14 at 2:17