Data File Format

When considering the way a data file is structured, three important aspects must be considered:

Geographic Identifier Formats

As described earlier, each geographic shape must have a unique identifier available for linking corresponding attribute data. The identifier formats can be a county code (FIPS code), a US postal ZIP code, a city limits code, a voting precinct code, a state or region code, the list goes on.

More information can be learned on the United States Census Bureau website by searching for geographic identifiers.

Note, it is most important that the same identifier format must be used when pairing independently imported data files. This will be apparent when we discuss how to link attribute data to a geographic shape.

There may be a need to convert an address to a specific geographic coordinate. The geocoder from the United States Census Bureau helps make this conversion.

Time Format

Time data, such as dates, are necessary when tracking how data values change through time. Often, attributes such as demographics change through time, while geographic information such as census district outlines change less frequently, if at all. When geographic information does not change over time it can be referred to as “static”, independent of time, or atemporal, and entered in Vesta as “always valid”.

Vesta only recognizes time information coded as a single column (i.e., single year or single day) in the import data file. This is different from SpaceStat, where a start date column and an end date column allowed the specification of different time intervals as temporal supports for the imported data.

This does not mean that the data file used at import must contain temporal data.

Information about when data exists is important in characterizing and modeling temporal trends. Vesta recognizes year (YYYY) and month/day/year (MM/DD/YYYY) date formats.

Time format for Shapefiles

Shapefiles do not distinguish between an attribute data column and a time data column; the shapefile will try to assign an identifier to time information as if it were an attribute data like rainfall. Any time variation must be externally applied upon a shapefile. This can be done in Vesta!

When importing a shapefile the user must select a specific date (such as when the data was collected - a static timestamp) or specific range of dates (such as a data collection period.) This import requirement helps the background processing steps in Vesta distinguish between a single observation per spatial object versus repeated observations per spatial object. This is important for when a user intends to assign temporal attribute data via a merged file to the imported shapefile.

Please reach out to us if you need help or guidance with time format.

Geographic Format

Using Shapefiles

Shapefiles can be easily found for a variety of geographies. The challenging part is in pairing new attribute data to an existing shapefile. The shapefile must be assessed first to know how the attribute data needs to be paired.

QGIS allows one to investigate shapefile layout and the identifier used. See the Creating a Data File page for more information on QGIS.

Vesta works with all types of geometric projections. If the shapefiles does not describe the projection (i.e., no file with extension ".prj") Vesta assumes EPSG:4326 projection.

Using Other File Formats

When importing any of the other compatible data file formats, geographic information must be included in separate columns. In Vesta, the coordinate information is expressed in latitude and longitude.

See the Data File Types section on the What is a Dataset page for details.