SigDiff
(Package: SDMTools) :
Identify Regions of Significant Differences
SigDiff computes the significance of the pairwise differences relative to the mean and variance of all differences between the two input datasets. This is useful for identifying regions of significant difference between two datasets (e.g., different DEMs (Januchowski et al. 2010) or different species distribution model predictions (Bateman et al 2010)).
ImageDiff is a wrapper to the image.asc command in adehabitat package that uses the result from SigDiff to create an image mapping the regions of significant differences (positive and negative).
NOTE: it is assumed the input data are of the same extent and cellsize.
● Data Source:
CranContrib
● Keywords:
● Alias: ImageDiff, SigDiff
●
1 images
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omission
(Package: SDMTools) :
Measures of Accuracy
Estimates different measures of accurracy given a confusion matrix.
● Data Source:
CranContrib
● Keywords:
● Alias: omission, prop.correct, sensitivity, specificity
●
0 images
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accuracy
(Package: SDMTools) :
Measures of Model Accuracy
accuracy estimates six measures of accuracy for presence-absence or presence-psuedoabsence data. These include AUC, ommission rates, sensitivity, specificity, proportion correctly identified and Kappa.
Note: this method will exclude any missing data.
● Data Source:
CranContrib
● Keywords:
● Alias: accuracy
●
0 images
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legend.gradient creates and displays a gradient legend on a plot or image file. The place and size of the legend is defined by coordinates, previously identified.
● Data Source:
CranContrib
● Keywords:
● Alias: legend.gradient
●
1 images
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ZonalStat
(Package: SDMTools) :
Landscape Zonal Statistics
ZonalStat calculates the statistics of data for specified zones of two matrices of data. The matrix can be a raster of class 'asc' (adehabitat package), 'RasterLayer' (raster package) or 'SpatialGridDataFrame' (sp package).
● Data Source:
CranContrib
● Keywords:
● Alias: ZonalStat
●
0 images
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lcmw
(Package: SDMTools) :
Least Cost Moving Windows Calculation
This is a moving window that for each cell returns the minimum 'cost' based on surrounding data cells and some dispersal distance cost.
● Data Source:
CranContrib
● Keywords:
● Alias: lcmw
●
0 images
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compare.matrix compares the values within two matrices (e.g., ESRI ArcInfo ASCII raster files) and produces a biplot that shows the frequency of each data combination shared between the matrices. The plot is overlayed with contour lines that demarcate parts of the the plot that share the same frequency of data combinations.
NOTE: it is assumed the matrices are of the same extent, cell size and scaled to be the same units.
● Data Source:
CranContrib
● Keywords:
● Alias: compare.matrix
●
3 images
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COGravity
(Package: SDMTools) :
Centre of Gravity or Mass calculations for spatial data
COGravity calculates the Centre of Gravity (or also known as Centre of Mass) for point or raster spatial data.
Note: NA data is automatically ommitted from analysis.
● Data Source:
CranContrib
● Keywords:
● Alias: COGravity
●
0 images
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wt.mean
(Package: SDMTools) :
Weighted mean, variance and standard deviation calculations
wt.mean calculates the mean given a weighting of the values.
wt.var is the unbiased variance of the weighted mean calculation using equations of GNU Scentific Library (http://www.gnu.org/software/gsl/manual/html_node/Weighted-Samples.htmland.
wt.sd is the standard deviation of the weighted mean calculated as the sqrt of wt.var.
Note: NA data is automatically ommitted from analysis.
● Data Source:
CranContrib
● Keywords:
● Alias: wt.mean, wt.sd, wt.var
●
0 images
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distance
(Package: SDMTools) :
Vincenty Direct Calculation of Distance and Direction
distance estimates the distance given a starting & ending latitude and longitude.
For general information on Vincenty's formula, see e.g., http://en.wikipedia.org/wiki/Vincenty's_formulae. It states:
Vincenty's formulae are two related iterative methods used in geodesy to calculate the distance between two points on the surface of an spheroid, developed by Thaddeus Vincenty in 1975. They are based on the assumption that the figure of the Earth is an oblate spheroid, and hence are more accurate than methods such as great-circle distance which assume a spherical Earth.
Note: this method assumes a locations are lat & lon given in WGS 84.
Direction, if requested, is the the initial bearing (sometimes referred to as forward azimuth) for which one would follow as a straight line along a great-circle arc from start to finish.
Note: this will fail if there are NA's in the data.
● Data Source:
CranContrib
● Keywords:
● Alias: distance
●
0 images
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