Package 'mop'

mop: Mobility Oriented-Parity Metric

Description

mop contains a set of tools to calculate the Mobility Oriented-Parity metric, which allows a user to compare a set of conditions of reference versus another set of of interest.

Details

The main goals of the MOP metric are to explore conditions in the set of interest that are non-analogous to those in the reference set, and to quantify how different conditions in the set of interest are from the reference set. The tools included here help to identify conditions outside the ranges of the reference set with greater detail than in other implementations. These tools are based on the methods proposed by Owens et al. (2013; doi:10.1016/j.ecolmodel.2013.04.011).

Functions in mop

mop, mop_distance, out_range, match_na_raster

Data included

reference_matrix, matrix_of_interest, reference_layers, layers_of_interest

Author(s)

Maintainer: Marlon E. Cobos [email protected] (ORCID)

Authors:

• Hannah L. Owens [email protected] (ORCID)

• Jorge Soberón [email protected] (ORCID)

• A. Townsend Peterson [email protected] (ORCID)

See Also

Useful links:

• https://github.com/marlonecobos/mop

• Report bugs at https://github.com/marlonecobos/mop/issues

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Example of variables for a set of interest

Description

A SpatRaster object representing variables in a set of interest. Variables represent future bioclimatic variables downloaded from the WorldClim database (https://worldclim.org/).

Format

A SpatRaster object.

Value

No return value. Used with function rast to bring raster variables to analysis.

Examples

layers_of_interest <- terra::rast(system.file("extdata",
                                              "layers_of_interest.tif",
                                              package = "mop"))

terra::plot(layers_of_interest)

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Match NA cells for all layers in SpatRaster

Description

Option to match cells with NA values in a SpatRaster with multiple layers.

Usage

match_na_raster(layers)

Arguments

layers

a SpatRaster object containing two or more variables to be matched.

Value

A SpatRaster object with NA cells matching in all layers.

Examples

# data
layers <- terra::rast(system.file("extdata", "reference_layers.tif",
                      package = "mop"))

# add NA in some places
layers[20:24, 10:16][, 3] <- NA
terra::plot(layers)

# match NAs
matched <- match_na_raster(layers)
terra::plot(matched)

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Example of matrix with variables in a set of interest

Description

A numeric table representing variables in a set of interest.

Usage

matrix_of_interest

Format

A matrix with 723 rows and 6 columns.

Examples

data("matrix_of_interest", package = "mop")

head(matrix_of_interest)

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Analysis of extrapolation risks using the MOP metric

Description

Analysis to calculate the mobility-oriented parity metric and other sub-products to represent dissimilarities and non-analogous conditions when comparing a set of reference conditions (M; m) against another set of conditions of interest (G; g).

Usage

mop(m, g, type = "basic",  calculate_distance = FALSE,
    where_distance = "in_range", distance = "euclidean",
    scale = FALSE, center = FALSE, fix_NA = TRUE, percentage = 1,
    comp_each = 2000, tol = NULL, rescale_distance = FALSE,
    parallel = FALSE, n_cores = NULL, progress_bar = TRUE)

Arguments

m	a SpatRaster or matrix of variables representing a set of conditions of reference (e.g., the set of conditions in which a model was calibrated). If a matrix is used, each column represents a variable.
g	a SpatRaster or matrix of variables representing a set of conditions of interest for which dissimilarity values and non-analogous conditions will be detected (e.g., conditions in which a model is projected). Variable names must match between m and g.
type	character, type of MOP analysis to be performed. See Details for options.
calculate_distance	logical, whether to calculate distances (dissimilarities) between m and g. The default, FALSE, runs rapidly and does not assess dissimilarity levels.
where_distance	character, where to calculate distances, considering how conditions in g are positioned in comparison to the range of conditions in m. See Details for options.
distance	character, which distances are calculated, euclidean or mahalanobis. Valid if calculate_distance = TRUE.
scale	scaling options, logical or numeric-alike as in scale.
center	logical or numeric-alike center options as in scale.
fix_NA	logical, whether to fix layers so cells with NA values are the same in all layers. Setting to FALSE may save time if the rasters are big and have no NA matching problems.
percentage	numeric, percentage of m closest conditions used to derive mean environmental distances to each combination of conditions in g.
comp_each	numeric, number of combinations in g to be used for distance calculations at a time. Increasing this number requires more RAM.
tol	tolerance to detect linear dependencies when calculating Mahalanobis distances. The default, NULL, uses .Machine$double.eps.
rescale_distance	logical, whether or not to re-scale distances 0-1. Re-scaling prevents comparisons of dissimilarity values obtained from runs with different values of percentage.
parallel	logical, whether calculations should be performed in parallel using n_cores of the computer. Using this option will speed up the analysis but will demand more RAM.
n_cores	numeric, number of cores to be used in parallel processing. If parallel = TRUE and n_cores = NULL (all CPU cores on current host - 1) will be used.
progress_bar	logical, whether to show a progress bar.

Details

type options return results that differ in the detail of how non-analogous conditions are identified.

• basic - makes calculation as proposed by Owens et al. (2013) doi:10.1016/j.ecolmodel.2013.04.011.

• simple - calculates how many variables in the set of interest are non-analogous to those in the reference set.

• detailed - calculates five additional extrapolation metrics. See mop_detailed under Value below for full details.

where_distance options determine what values should be used to calculate dissimilarity

• in_range - only conditions inside m ranges

• out_range - only conditions outside m ranges

• all - all conditions

When the variables used to represent conditions have different units, scaling and centering are recommended. This step is only valid when Euclidean distances are used.

Value

A object of class mop_results containing:

• summary - a list with details of the data used in the analysis:

  • variables - names of variables considered.

  • type - type of MOP analysis performed.

  • scale - value according to the argument scale.

  • center - value according to the argument center.

  • calculate_distance - value according to the argument calculate_distance.

  • distance - option regarding distance used.

  • percentage - percentage of m used as reference for distance calculation.

  • rescale_distance - value according to the argument rescale_distance.

  • fix_NA - value according to the argument fix_NA.

  • N_m - total number of elements (cells with values or valid rows) in m.

  • N_g - total number of elements (cells with values or valid rows) in g.

  • m_ranges - matrix with ranges of variables in reference conditions (m).

• mop_distances - if calculate_distance = TRUE, a SpatRaster or vector with distance values for the set of interest (g). Higher values represent greater dissimilarity compared to the set of reference (m).

• mop_basic - a SpatRaster or vector, for the set of interest, representing conditions in which at least one of the variables is non-analogous to the set of reference. Values should be: 1 for non-analogous conditions, and NA for conditions inside the ranges of the reference set.

• mop_simple - a SpatRaster or vector, for the set of interest, representing how many variables in the set of interest are non-analogous to those in the reference set. NA is used for conditions inside the ranges of the reference set.

• mop_detailed - a list containing:

  • interpretation_combined - a data.frame to help identify combinations of variables in towards_low_combined and towards_high_combined that are non-analogous to m.

  • towards_low_end - a SpatRaster or matrix for all variables representing where non-analogous conditions were found towards low values of each variable.

  • towards_high_end - a SpatRaster or matrix for all variables representing where non-analogous conditions were found towards high values of each variable.

  • towards_low_combined - a SpatRaster or vector with values representing the identity of the variables found to have non-analogous conditions towards low values. If vector, interpretation requires the use of the data.frame interpretation_combined.

  • towards_high_combined - a SpatRaster or vector with values representing the identity of the variables found to have non-analogous conditions towards high values. If vector, interpretation requires the use of the data.frame interpretation_combined.

See Also

mop_distance, out_range

Examples

# data
reference_layers <- terra::rast(system.file("extdata", "reference_layers.tif",
                                            package = "mop"))

layers_of_interest <- terra::rast(system.file("extdata",
                                              "layers_of_interest.tif",
                                              package = "mop"))

# analysis
mop_res <- mop(m = reference_layers, g = layers_of_interest)

summary(mop_res)

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MOP distance calculation

Description

Calculates distances from each of the points of interest in g_matrix to a defined percentage of the reference conditions in m_matrix.

Usage

mop_distance(m_matrix, g_matrix, distance = "euclidean", percentage = 1,
             comp_each = 2000, tol = NULL, parallel = FALSE, n_cores = NULL,
             progress_bar = TRUE)

Arguments

m_matrix	matrix of variables representing the set of conditions to be used as reference. Each column represents a variable.
g_matrix	matrix of variables representing the set of conditions to be compared against the reference conditions (where distances are to be calculated). Each column represents a variable. Variable names must match those in m_matrix.
distance	character, one of two options: "euclidean" or "mahalanobis".
percentage	numeric, percentage of points of m (the closest ones) used to derive mean environmental distances to each g point.
comp_each	numeric, number of points of the g matrix to be used for distance calculations at a time (default = 2000). Increasing this number requires more RAM.
tol	tolerance to detect linear dependencies when calculating Mahalanobis distances. The default, NULL, uses .Machine$double.eps.
parallel	logical, if TRUE, calculations will be performed in parallel using n_cores of the computer. Using this option will speed up the analysis but will demand more RAM.
n_cores	numeric, number of cores to be used in parallel processing. Uses current host CPU cores - 1 by default.
progress_bar	logical, whether to show a progress bar for calculations. Valid when calculations are not run in parallel.

Value

A numeric vector with values of distances calculated according to parameters used.

Examples

# data
data("reference_matrix", package = "mop")
data("matrix_of_interest", package = "mop")

# analysis
mop_dist <- mop_distance(m_matrix = reference_matrix,
                         g_matrix = matrix_of_interest)

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Constructor of S3 objects of class mop_results

Description

Constructor of S3 objects of class mop_results

Usage

new_mop_results(summary = new("list"), mop_distances = NULL,
                mop_basic = NULL, mop_simple = NULL,
                mop_detailed = new("list"))

Arguments

summary	a list with a summary of the data and parameters used in analysis. Default = empty list.
mop_distances	a SpatRaster or numeric vector of distances from the set of conditions of reference to the set of conditions of interest. Default = NULL.
mop_basic	a SpatRaster or numeric vector showing conditions in the set of interest outside the ranges in the reference set. The value 1 indicates conditions outside one or more ranges. Default = NULL.
mop_simple	a SpatRaster or numeric vector showing conditions in the set of interest outside the ranges in the reference set. Values indicate how many variables are outside reference ranges. Default = NULL.
mop_detailed	a list with a detailed representation of mop results in conditions outside the range of reference. Default = empty list.

Value

An object of class mop_results.

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Detect values outside ranges of reference conditions

Description

Options to identify which values in a set of conditions of interest (g_matrix) are outside the range of a set of conditions of reference (m_matrix).

Usage

out_range(m_matrix, g_matrix, type = "basic")

Arguments

m_matrix	matrix of variables representing the set of conditions to be used as reference. Each column represents a variable.
g_matrix	matrix of variables representing the set of conditions to be compared against the reference conditions (where conditions outside range are to be detected). Each column represents a variable. Variable names must match those in m_matrix.
type	character, type of identification to be performed. See Details for options.

Details

Results are produced according to type:

• basic - helps to identify conditions outside ranges, in general, one or variables are only counted as 1. This is always returned.

• simple - identifies the number of variables with conditions outside ranges, for each condition of interest outside ranges, the number of non-analogous variables is returned.

• detailed - produces various results (including the two above):

  • high_all - identifies non-analogous conditions towards high values of variables, for each variable independently.

  • low_all - identifies non-analogous conditions towards low values of variables, for each variable independently.

  • high_combined - values are used to identify combinations of variables with non-analogous conditions towards high values of the variables.

  • low_combined - values are used to identify combinations of variables with non-analogous conditions towards low values of the variables.

  • interpretation - a data.frame to help identify which variables are considered in combined results.

Value

A list containing the ranges in m_matrix, results from analysis according to type, and table to help with interpretations. NA values represent conditions of interest inside ranges of reference conditions. See Details.

Examples

# data
data("reference_matrix", package = "mop")
data("matrix_of_interest", package = "mop")

# analysis
out <- out_range(m_matrix = reference_matrix,
                 g_matrix = matrix_of_interest)

---

Print a short version of elements in mop objects

Description

Print a short version of elements in mop objects

Usage

## S3 method for class 'mop_results'
print(x, ...)

Arguments

x	object of class mop_results.
...	further arguments to be passed to or from other methods. Ignored in this function.

Value

A short description of objects in the console.

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Example of variables for a set of reference

Description

A SpatRaster object representing variables in a set of reference. Variables represent current bioclimatic variables downloaded from the WorldClim database (https://worldclim.org/).

Format

A SpatRaster object.

Value

No return value. Used with function rast to bring raster variables to analysis.

Examples

reference_layers <- terra::rast(system.file("extdata", "reference_layers.tif",
                                            package = "mop"))

terra::plot(reference_layers)

---

Example of matrix with variables in a set of reference

Description

A numeric table representing variables in a set of reference.

Usage

reference_matrix

Format

A matrix with 723 rows and 6 columns.

Examples

data("reference_matrix", package = "mop")

head(reference_matrix)

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Summary of attributes and results

Description

Summary of attributes and results

Usage

## S3 method for class 'mop_results'
summary(object, ...)

Arguments

object	object of class mop_results.
...	additional arguments affecting the summary produced. Ignored in this function.

Value

A printed summary.

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