Implements spatial error estimation and
    permutation-based variable importance measures for predictive models
    using spatial cross-validation and spatial block bootstrap.

Performs non-parametric tests of parametric specifications.
    Five tests are available. 
    Specific bandwidth and kernel methods can be chosen along with many other options. 
    Allows parallel computing to quickly compute p-values based on the bootstrap. 
    Methods implemented in the package are H.J. Bierens (1982) <doi:10.1016/0304-4076(82)90105-1>,
    J.C. Escanciano (2006) <doi:10.1017/S0266466606060506>,
    P.L. Gozalo (1997) <doi:10.1016/S0304-4076(97)86571-2>,
    P. Lavergne and V. Patilea (2008) <doi:10.1016/j.jeconom.2007.08.014>,
    P. Lavergne and V. Patilea (2012) <doi:10.1198/jbes.2011.07152>,
    J.H. Stock and M.W. Watson (2006) <doi:10.1111/j.1538-4616.2007.00014.x>,
    C.F.J. Wu (1986) <doi:10.1214/aos/1176350142>,
    J. Yin, Z. Geng, R. Li, H. Wang (2010) <https://www.jstor.org/stable/24309002>
    and J.X. Zheng (1996) <doi:10.1016/0304-4076(95)01760-7>.

We provide functionality to implement penalized PCA with an option to smooth the objective function using Nesterov smoothing. Two functions are available to compute a user-specified number of eigenvectors. The function unsmoothed_penalized_EV() computes a penalized PCA without smoothing and has three parameters (the input matrix, the Lasso penalty, and the number of desired eigenvectors). The function smoothed_penalized_EV() computes a smoothed penalized PCA using the same parameters and additionally requires the specification of a smoothing parameter. Both functions return a matrix having the desired eigenvectors as columns.

Functions to produce a fully fledged 'geo-spatial' object extent as a
    'SpatialPolygonsDataFrame'. Also included are functions to generate polygons
    from raster data using 'quadmesh' techniques, a round number buffered extent, and
    general spatial-extent and 'raster-like' extent helpers missing from the originating
    packages. Some latitude-based tools for polar maps are included.