# R/fit_transformation_df.R In TriDimRegression: Bayesian Statistics for 2D/3D Transformations

#### Documented in fit_transformation_df

```#' Fitting Bidimensional or Tridimensional Regression / Geometric Transformation Models via Two Tables.
#'
#' @description
#' Fits Bidimensional or Tridimensional regression / geometric transformation models using
#' Stan engine. Two sets of coordinates are supplied via \code{iv} (for an independent variable)
#' and \code{dv} (for the dependent one). The two tables must have the same dimensions
#' (both N×2 or N×3).
#'
#' For the 2D data, you can fit \code{"translation"} (2 for translation only), \code{"euclidean"}
#' (4 parameters: 2 for translation, 1 for scaling, and 1 for rotation),
#' \code{"affine"} (6 parameters: 2 for translation and 4 that jointly describe scaling, rotation and sheer),
#' or \code{"projective"} (8 parameters: affine plus 2 additional parameters to account for projection).
#'
#' For 3D data, you can fit \code{"translation"} (3 for translation only), \code{"euclidean_x"}, \code{"euclidean_y"},
#' \code{"euclidean_z"} (5 parameters: 3 for translation scale, 1 for rotation, and 1 for scaling),
#' \code{"affine"} (12 parameters: 3 for translation and 9 to account for scaling, rotation, and sheer),
#' and \code{"projective"} (15 parameters: affine plus 3 additional parameters to account for projection).
#' transformations.
#'
#' For details on transformation matrices and computation of scale and rotation parameters please
#' see \code{vignette("transformation_matrices", package = "TriDimRegression")}
#'
#' @param iv a data frame containing independent variable, must by numeric only, N×2 or N×3.
#' @param dv a data frame containing dependent variable, must by numeric only, N×2 or N×3.
#' @param transformation the transformation to be used: \code{"translation"} (both 2D and 3D), \code{"euclidean"} (2D),
#'   \code{"euclidean_x"}, \code{"euclidean_y"}, \code{"euclidean_z"} (3D, rotation about, respectively, x, y, and z axis),
#'   \code{"affine"} (2D and 3D), or \code{"projective"} (2D and 3D).
#' @param priors named list of parameters for prior distributions of parameters \code{a}
#'   (translation, normal distribution), \code{b} (all other parameters, normal distribution),
#'   and \code{sigma} (residual variance, exponential). E.g., \code{list("a" = c(0, 10), "b"= c(0, 1), "sigma"=1)}.
#'   Default priors are \code{"a" = c(0, max_absolute_difference_in_means(d, iv)) / 2)},
#'   \code{"b" = c(0, max_absolute_difference_in_means(d, iv)) / 2)}, \code{"sigma" = 1 * sd(dv)}.
#' @param chains Number of chains for sampling.
#' @param cores Number of CPU cores to use for sampling. If omitted, all available cores are used.
#' @return A [tridim_transformation][tridim_transformation-class()] object
#' @export
#' @examples
#' # Geometric transformations of 2D data
#' tr3 <- fit_transformation_df(Face3D_W070, Face3D_W097, transformation ='translation')

fit_transformation_df <- function(iv, dv, transformation, priors=NULL, chains=1, cores=NULL, ...) {
if (!is.data.frame(dv) && !is.matrix(dv)) stop("dv must be a data.frame or a matrix")
if (!is.data.frame(iv) && !is.matrix(iv)) stop("iv must be a data.frame or a matrix")

tridim <- tridim_transformation(transformation, as.matrix(iv), as.matrix(dv), formula=NULL, priors=priors)

# fitting function
tridim\$stanfit <- rstan::sampling(tridim\$stanmodel,
data=tridim\$data,
chains=chains,
cores=ifelse(is.null(cores), future::availableCores(), cores),
...)
tridim
}
```

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TriDimRegression documentation built on Oct. 5, 2021, 9:11 a.m.