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Description

The Interval class is an S4 class that stores the results of Intensity Analysis at the Interval level. This is the first level of intensity analysis, which examines how the size and rate of change varies across time intervals.

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Class Definition

setClass(
  Class = "Interval",
  slots = c(intervalData = "tbl_df")
)

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Slots

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intervalData
tibble (tbl_df)
A table with the results of an Intensity analysis at the Interval level, containing St (annual intensity) and U (uniform intensity) values.Must be a tibble with exactly 4 columns:
  1. Period (<fct>): The period of interest [Yt, Yt+1]
  2. PercentChange (<dbl>): Changed area on the Interval level (%)
  3. St (<dbl>): Annual intensity of change for the time period [Yt, Yt+1]
  4. U (<dbl>): Uniform intensity for a LUC category change in the time period of interest

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Details

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Interval Level Analysis

The Interval level is the first of three levels in Intensity Analysis. It answers the question: “How does the rate of change vary across time intervals?”
  • St (Annual Intensity): The observed annual rate of change during each time interval
  • U (Uniform Intensity): The hypothetical rate of change if the total change were distributed uniformly across all time intervals
By comparing St to U:
  • If St > U: The interval experienced faster change than the overall average
  • If St < U: The interval experienced slower change than the overall average

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Validity Check

The class includes a validity function that ensures:
  • The intervalData slot contains a tibble (tbl_df)
  • The tibble has exactly 4 columns

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Usage in Intensity Analysis

The Interval object is created by the intensityAnalysis() function: 
# Run intensity analysis
my_test <- intensityAnalysis(
  dataset = SL_2002_2014,
  category_n = "Ap",
  category_m = "SG"
)

# Access the Interval level result
interval_result <- my_test$interval_lvl

# View the object
interval_result
#> An object of class "Interval"
#> Slot "intervalData":
#> # A tibble: 4 × 4
#>   Period    PercentChange    St     U
#>   <fct>             <dbl> <dbl> <dbl>
#> 1 2002-2008          5.23  0.87  0.92
#> 2 2008-2010          4.82  2.41  0.92
#> 3 2010-2012          4.24  2.12  0.92
#> 4 2012-2014          3.32  1.66  0.92

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Plotting

The Interval class has a dedicated plot method: 
plot(interval_result)
This generates a visualization showing:
  • Annual intensity (St) for each time interval as bars
  • Uniform intensity (U) as a reference line
  • Easy identification of intervals with faster or slower change

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See Also

  • Category - S4 class for Category level analysis
  • Transition - S4 class for Transition level analysis
  • intensityAnalysis() - Function that creates Interval objects
  • plot() - Method for visualizing Interval objects

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