6.9.6. Conditional expressions using the raster calculator

To statistically analyse the area covered by three land cover types of interest (arable land, coniferous, and mixed forest) within the 2 km buffers (created in section, we will first create three new raster layers using raster calculator.

  1. Open the Raster calculator (Spatial Analyst Tools > Map Algebra > Raster calculator).
  2. Combine Layers and Variables and functions until the Raster calculator expression equals “Con("g100_06_ch_FR.tif" == 12, 1, 0)” (Fig. 53) (12 is the raster value for “Non-irrigated arable land” in the CLC06 dataset). The expression is a conditional statement (Con) which literally means: if the value of a pixel from the g100_06_ch_FR.tif layer equals 12, assign that pixel a new value of 1. If not, assign a value of 0. This will create a binary raster.
  3. Specify an output raster, e.g. lc_class211.tif, which denotes that the new layer will represent the 211 (Non-irrigated arable land) land cover code.
  4. Click OK.
  5. Repeat steps 45 to 48 with the following raster values: 24 (replaces 12 in the equation in step 46.) (class 312 as the output, Coniferous forest) and 25 (class 313, Mixed forest).

The newly created raster images contain zones with the value 1 (where the Raster calculator expression was true, i.e. the land cover represents the non-irrigated arable land category) and 0, where the expression was false (i.e. the land cover does not represent the non-irrigated arable land category).

Fig. 53. The Raster Calculator dialog box showing the equation used to select all of the land cover code 211 from the entire raster.