Spatial Analysis of Accessibility of Wells using Map Algebra
In this tutorial we'll apply map algebra to determine the accessibilty of wells. This tutorial was developed together with Kurt Menke (Bird's Eye View GIS).
3. Condition 1: Wells within 150 Meters of Houses or Roads
3.1. Style a discrete raster layer
Let's first look at the houses. The houses are a class in the buildg layer. Rasters normally only store values, so we need to assign a proper legend to raster layers.
1. In the Layers panel click on the 
to open the Layer styling panel.
2. Choose Paletted/Unique values as render type. Keep Random as Color ramp type and click Classify.
3. Use the screenshot below as a reference to add the labels to the class numbers by double-clicking on each label name. Double-click on the color to make it more intuitive as shown in the example.
Because buildg is a discrete raster we used the Paletted/Unique values render type. This renderer classifies each unique integer value found in the raster layer.