from numpy array to csv - rounding

[SchroedingersLion]

Curious though, why do you want to round floats to 3 digits in a csv file? It's not like csv is a presentation format.

I want to lose precision so that the file size does not get unnecessarily large. Saving, say, 5 digits instead of the usual 15 saves a factor 3 then. I work in scientific computing and result files often store millions of floats, so stuff like this pays off.