Article 4: Understanding the overall_suit function
In ALUES: Agricultural Land Use Evaluation System

knitr::opts_chunk$set(echo = TRUE)

The overall suitability can be computed using the overall_suit function, which takes an object of class suitability. For example,

library(ALUES)
banana_suit <- suit("banana", terrain=MarinduqueLT)
class(banana_suit[["terrain"]])
class(banana_suit[["soil"]])

There are no factors that were targetted for the terrain characteristics, hence the returned value is a string error. Thus, only the soil characteristics can have an overall suitability, and is computed as follows:

ovsuit <- overall_suit(banana_suit[["soil"]])
head(ovsuit)

By default, the overall_suit function uses minimum as a summary statistics, hence the 0 scores and N classes across land units. To adjust this to average aggregation, use the method argument to specify.

ovsuit <- overall_suit(banana_suit[["soil"]], method="average")
head(ovsuit)

Intervals

By default, the overall_suit uses an equally spaced interval for the suitability classes, that is, N [0, 0.25), S3 [0.25, 0.50), S2 [0.50, 0.75), and S1 [0.75, 1]. This can be changed using the interval argument, for example

ovsuit <- overall_suit(banana_suit[["soil"]], method="average", interval=c(0, 0.6, 0.7, 0.9, 1))
head(ovsuit)

The above code sets the suitability class intervals into: N [0, 0.60), S3 [0.60, 0.70), S2 [0.70, 0.90), and S1 [0.90, 1]. It should be emphasized that the interval argument cannot be set to unbias as in the case of the interval argument of the suit function. This follows from the fact that the overall_suit function is not using a membership function for computing the score, but an aggregation function.