eik = total length (m) of edge in landscape between patch types (classes) i and k.
E = total length (m) of edge in landscape, excluding background.
m = number of patch types (classes) present in the landscape, including the landscape border, if present.
Description IJI equals minus the sum of the length (m) of each unique edge type divided by the total landscape edge (m), multiplied by the logarithm of the same quantity, summed over each unique edge type; divided by the logarithm of the number of patch types times the number of patch types minus 1 divided by 2; multiplied by 100 (to convert to a percentage). In other words, the observed interspersion over the maximum possible interspersion for the given number of patch types. Note, IJI considers all patch types present on an image, including any present in the landscape border, if present. All background edge segments are ignored, as are landscape boundary segments if a border is not provided, because adjacency information for these edge segments is not available and the intermixing of classes with background is assumed to be irrelevant.
Units Percent
Range 0 < IJI ≦ 100
IJI approaches 0 when the distribution of adjacencies among unique patch types becomes increasingly uneven. IJI = 100 when all patch types are equally adjacent to all other patch types (i.e., maximum interspersion and juxtaposition). IJI is undefined and reported as "N/A" in the "basename".land file if the number of patch types is less than 3.
Comments Interspersion and juxtaposition index is based on patch adjacencies, not cell adjacencies like the contagion index. As such, it does not provide a measure of class aggregation like the contagion index, but rather isolates the interspersion or intermixing of patch types.