NetCDF _FillValue, missing_value and NaN Together (.nc)
One variable that hides absent data three different ways at once: two _FillValue cells, one legacy missing_value cell and one raw NaN, with valid_min and valid_max also declared. Averaging the raw array without honouring all three gives roughly -60 K instead of a real mean.
| Cell (time,lat,lon) | Stored value | Convention | Should read as |
|---|---|---|---|
| (0,0,0) | -9999.0 | _FillValue | masked / missing |
| (1,2,3) | -9999.0 | _FillValue | masked / missing |
| (2,4,1) | -8888.0 | missing_value (legacy) | masked / missing |
| (3,1,5) | NaN | raw IEEE-754 NaN | masked / missing |
| all others | 260 to 292 | real value | a temperature in K |
Specifications
- Fill Value
- -9999
- Missing Value
- -8888
- Raw Na N
- true
- Fill Cells
- 2
- Missing Cells
- 1
- Nan Cells
- 1
- Valid Min
- 200
- Valid Max
- 330
- Total Cells
- 120
Testing contract
Expected to pass- Scenario
- Read tas with masking enabled and compute the mean of the unmasked cells only.
- Expected result
- Exactly four of the 120 cells mask out and the resulting mean falls between 260 K and 292 K; ignoring any one convention drags the mean below zero or leaves a NaN.
What is a .nc file?
NetCDF (.nc, Network Common Data Form) is a binary, self-describing format for array-oriented scientific data. It stores multidimensional variables (like temperature over latitude, longitude, and time) with named dimensions, units, and metadata attributes, and is a standard in climate, ocean, and geoscience.
How to use this file
Use an example .nc file to test NetCDF readers (netCDF4, xarray, Panoply), CF-convention validators, and gridded-data pipelines, or to verify dimension and variable extraction.
How to use this file for testing
“NetCDF _FillValue, missing_value and NaN Together (.nc)” is a deterministic Novus Examples fixture for Scientific data, Serialization testing, Error handling. Citation catalogs (BibTeX, RIS), chemistry structures (MDL Molfile, PDB), and gridded binary data (NetCDF, FITS) — for testing reference managers, molecule viewers, and scientific-data loaders.
Documented properties for this file: NC · 1,480 bytes. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.
Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such — expect parsers to fail loudly rather than silently accept them.
Scientific fixtures are small, valid, and fully synthetic — no real organism, patient, sample, or observation. Point your parser or loader at the file and check it reads the documented records, variables, or headers; binary formats ship a readable twin or metadata listing for comparison.
Related files
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- h5HDF5 Degenerate Shapes — Scalar, Zero-Length and Null (.h5)Five degenerate but entirely legal datasets — a rank-0 scalar, a zero-length vector, a (0, 5) array, a single-element vector and a NULL dataspace — plus an empty group. None of them is corrupt, and a reader that reports them as errors is the thing being tested.
- h5HDF5 Hard, Soft and Dangling Links (.h5)One array reachable under four names: itself, a hard link sharing its object address, a soft link resolved at access time, and a soft link pointing nowhere. A walker that counts names instead of object addresses reports four arrays and then crashes on the dangling one.
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