What is a shapefile?

2022-05-03

Shapefile, What is a shapefile

A shapefile is a geospatial vector data format developed by the ESRI (Environmental Systems Research Institute) for geographic information system (GIS) software. Shapefiles are the ideal format for the exchange of geographical data because they contain both geometric data (for mapping points, lines, and polygons) as well as the data attributes. This format is frequently used in GIS software such as Mapinfo, Arcgis, QGIS, Tableau Software, Excel (3D) Maps, and our own Spotzi Geomarketing Platform.

Specifications

Shapefiles (.shp) are a prized format when it comes to geographic data, but they're not a solo file type. These files are a mandatory part of file collections — often compressed into ZIP file formats (.zip) — and these collections require a minimum of the following 3 file types before being used within a GIS software:

Shape format (.shp) - the format containing your data's geometry.
Shape index format (.shx) - the positional index of your geometry which allows for quick forward/backward seeking.
dBase attribute format (.dbf) - the columnar attributes for each of your shapes.

Shapefiles exported from Spotzi's platform also contain the following (noncompulsory) files:

Projection format (.prj)- the coordinate system and projection information of your dataset;
Code page file (.cpg) - the file for identifying character encoding.

Here are some other optional files that can be included within a zipped shapefile:

A spatial index of the features (.sbn and .sbx)
A read-only spatial index of the features (.fbn and .fbx)
An attribute index of the active fields within a table (.ain and .aih)
A geocoding index for read-write datasets (.ixs or .mxs)
An attribute index for the .dbf file in the form of shapefile.columnname.atx (.atx)
Geospatial metadata in XML format, such as ISO 19115 or other XML schema (.shp.xml)
An alternative quadtree spatial index used by MapServer and GDAL/OGR software (.qix)