# Lesson 2. GIS in R: shp, shx and dbf + prj - the files that make up a shapefile

## Learning objectives

After completing this tutorial, you will be able to:

• Be able to list the 3 core files associated with a shapefile

## What you need

You will need a computer with internet access to complete this lesson and the data for week 5 of the course.

## One dataset - many files

While text files often are self contained (one CSV) is composed of one unique file, many spatial formats are composed of several files. A shapefile is created by 3 or more files, all of which must retain the same NAME and be stored in the same file directory, in order for you to be able to work with them.

### Shapefile structure

There are 3 key files associated with any and all shapefiles:

• .shp: the file that contains the geometry for all features.
• .shx: the file that indexes the geometry.
• .dbf: the file that stores feature attributes in a tabular format.

These files need to have the same name and to be stored in the same directory (folder) to open properly in a GIS, R or Python tool.

Sometimes, a shapefile will have other associated files including:

• .prj: the file that contains information on projection format including the coordinate system and projection information. It is a plain text file describing the projection using well-known text (WKT) format.
• .sbn and .sbx: the files that are a spatial index of the features.
• .shp.xml: the file that is the geospatial metadata in XML format, (e.g. ISO 19115 or XML format).

## Data management - sharing shapefiles

When you work with a shapefile, you must keep all of the key associated file types together. And when you share a shapefile with a colleague, it is important to zip up all of these files into one package before you send it to them!