ncdiff

Compare either two NetCDF files or all NetCDF files in two directories.

Usage

Chunking and RAM design

This tool does not support chunked files, or loading only part of large datasets into memory at once. Instead, chunked datasets are loaded as individual files. One variable at a time is then loaded into memory completely, compared, and then discarded.

This has the big advantage of simplicity, but a few disadvantages:

• No option to compare datasets with mismatched prefixes (e.g. foo.*.nc vs. bar.*.nc).
• No option to compare chunked datasets that differ only in chunking
• Slower, as there is no option to skip loading over and over again variables that don’t sit on the concat_dim. See also xarray#2039.
• Huge RAM usage in case of monolithic variables

Further limitations

• Won’t compare NetCDF settings, e.g. store version, compression, chunking, etc.
• Doesn’t support indices with duplicate elements