Shapefile data in Portugal: sources and checks

What the source records show

The selected country export contains 46,277 listed format declarations across 40 publishers.

Shapefile accounts for 0.7% of that declaration total.

A resource record describes a file or a service. Several records can belong to one dataset.

The export retains up to 20 format labels per publisher. It excludes some small publishers and empty format labels.

Choose a source

The largest matching entry is Câmara Municipal de Cascais.

It contributes 120 matching resource records, or 37.6% of this format sample.

The next entry contributes 65 matching records.

A large count indicates more catalogue records. It does not establish accuracy, completeness, or public access.

1. Open a source record from the examples below.
2. Confirm the geographic area and observation period on the source page.
3. Read the licence for the selected dataset.
4. Select the required file or service from the source page.

Inspect the format

A Shapefile dataset uses several companion files. The geometry file alone does not contain all attributes.

1. Keep the SHP, SHX, DBF, and available PRJ files together.
2. Check the character encoding of the attribute table.
3. Confirm the coordinate reference system before a spatial join.
4. Inspect field names after an export to a different format.
5. Compare feature counts before and after conversion.

Check the result

A format label does not verify the file contents. A source can change its files after the catalogue export.

A metadata modification date can describe a catalogue edit. It does not necessarily describe the latest observation.

1. Record the source URL, access date, and dataset title.
2. Check the units and the definitions of the fields.
3. Compare a small sample with the source documentation.
4. Retain an original copy before any conversion.
5. State any missing periods, regions, or values in the result.

How this comparison works

The calculation sums listed format declarations from the publisher export.

It groups equivalent format labels and retains separate counts for XLS, XLSX, TIFF, and GeoTIFF.

Compound labels can remain outside the selected format group. The source files retain the original labels.

The source records can include several versions of the same data. The totals do not count unique observations.

The examples are selections from stored catalogue samples. They do not list every matching dataset.