GIS is a combination of software and data that informs us about the location of something and its relation to others. In GIS, every dataset is associated with a coordinate system, which is a system for representing the locations of different geographic features and different measurements. There are two main types of coordinate systems: geographic coordinate systems (GCS) and projected coordination systems. One example of GCS is using latitude-longitude, and one example of a projected coordination system is the transverse Mercator system. Whereas GCS uses a three-dimensional spherical surface, the projected coordination system uses two dimensions for representing spatial data. Data is used in GCS to define the position of the spheroid in relation to the center of the earth; a very commonly used GCS is WGS 84.

Now, we will work with a shapefile in QGIS and find out its projection system. First, we import a shapefile named BGD_adm4.shp from the folder Data under Chapter 2. To recall how to import a vector file, refer back to Chapter 1, Setting Up R and QGIS Environments for Geospatial Tasks.

Now, we will see the shapefile as follows:

Now, to check out the projection system it is using, we need to click on Project Properties under Project in the menu bar as instructed in the following screenshot:

1. Click on Project and then Properties... under it:

2. Now, click on CRS:

Now, we can see the coordinate system (a) and the spatial extent and projection (b) as shown in this screenshot:

We can also select and change CRS from the Layer panel. We can do so using the following steps:

1. Right-click on the BGD_adm4 layer in the Layer panel. Click on Properties as highlighted...

In this chapter, we learned about the basics of GIS and learned particularly how vector data is stored in R and QGIS. We learned to import point data from an Excel file and how to plot it on a map in R. We used the ggmap package of R to accomplish this task along with various options for plotting these. The sp package of R has six main classes for dealing with spatial data: SpatialPoints, SpatialPointsDataFrame, SpatialLines, SpatialLinesDataFrame, SpatialPolygons, and SpatialPolygonsDataFrame. We learned to use the readOGR() function of the sp package for importing shapefiles containing different vector classes. In this chapter, we also learned to visualize quantitative and qualitative data in R.

We also learned how to use QGIS for vector data importation and how to visualize those. Importing Excel files to QGIS was also discussed, along with visualizing quantitative...

After completing this chapter, readers should be comfortable answering the following questions:

• What are the spatial data classes available in R (sp package)?
• How can users visualize spatial data in R?
• How can users import shapefiles and use background maps in R?
• How is CRS set in QGIS?
• How is quantitative and qualitative data visualized in QGIS?
• How are text diagrams used in QGIS?
• How may background maps be added?

When going through vector data manipulation in R, we have just touched the surface of what could be possible using R. We will cover other data manipulation techniques as we step on through new chapters. But if you want to have a more in-depth discussion about these topics, you can have a look at the book Learning R for Geospatial Analysis by Michael Dorman and An Introduction to R for Spatial Analysis and Mapping by Brunsdon and Comber. For QGIS, if you want better coverage of visualizing and stylizing vector data, QGIS by Example by Bruy and Svidzinska and Mastering QGIS by Menke et al. are two great reads.