add S3 utility functions

attach the class to an object:
- osem_as_sensebox
- osem_as_measurements

retain the class after filtering / mutating / subsetting:
- filter.sensebox
- filter.osem_measurements
- mutate.sensebox
- mutate.osem_measurements
- `[.sensebox`
- `[.osem_measurements`

NAMESPACE

@@ -1,5 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
+S3method("[",osem_measurements)
+S3method("[",sensebox)
 S3method(osem_measurements,bbox)
 S3method(osem_measurements,default)
 S3method(osem_measurements,sensebox)
@@ -8,6 +10,16 @@ S3method(plot,osem_measurements)
 S3method(plot,sensebox)
 S3method(print,sensebox)
 S3method(summary,sensebox)
+export(filter.osem_measurements)
+export(filter.sensebox)
+export(filter_.osem_measurements)
+export(filter_.sensebox)
+export(mutate.osem_measurements)
+export(mutate.sensebox)
+export(mutate_.osem_measurements)
+export(mutate_.sensebox)
+export(osem_as_measurements)
+export(osem_as_sensebox)
 export(osem_as_sf)
 export(osem_box)
 export(osem_boxes)

R/00utils.R

@@ -28,3 +28,13 @@ utc_date = function (date) {
 
 # NOTE: cannot handle mixed vectors of POSIXlt and POSIXct
 date_as_isostring = function (date) format.Date(date, format = '%FT%TZ')
+
+#' Simple factory function meant to implement dplyr functions for other classes,
+#' which call an callback to attach the original class again after the fact.
+#'
+#' @param callback The function to call after the dplyr function
+#' @noRd
+dplyr_class_wrapper = function(callback) {
+  function(.data, ..., .dots) callback(NextMethod())
+}
+

R/api.R

@@ -41,8 +41,7 @@ get_measurements_ = function (..., endpoint) {
     ))
   })
 
-  class(result) = c('osem_measurements', class(result))
-  result
+  osem_as_measurements(result)
 }
 
 get_stats_ = function (endpoint) {

R/box.R

@@ -126,6 +126,5 @@ parse_senseboxdata = function (boxdata) {
     thebox$height = location[[1]]$geometry$coordinates[[3]]
 
   # attach a custom class for methods
-  class(thebox) = c('sensebox', class(thebox))
-  thebox
+  osem_as_sensebox(thebox)
 }

R/box_utils.R

@@ -73,3 +73,30 @@ summary.sensebox = function(object, ...) {
 
   invisible(object)
 }
+
+#' Converts a foreign object to an sensebox data.frame.
+#' @param x A data.frame to attach the class to
+#' @export
+osem_as_sensebox = function(x) {
+  ret = as.data.frame(x)
+  class(ret) = c('sensebox', class(x))
+  ret
+}
+
+#' @export
+filter_.sensebox = dplyr_class_wrapper(osem_as_sensebox)
+#' @export
+filter.sensebox = dplyr_class_wrapper(osem_as_sensebox)
+#' @export
+mutate_.sensebox = dplyr_class_wrapper(osem_as_sensebox)
+#' @export
+mutate.sensebox = dplyr_class_wrapper(osem_as_sensebox)
+
+#' maintains class / attributes after subsetting
+#' @noRd
+#' @export
+`[.sensebox` = function(x, i, ...) {
+  s = NextMethod('[')
+  mostattributes(s) = attributes(x)
+  s
+}

R/measurement_utils.R

@@ -6,3 +6,31 @@ plot.osem_measurements = function (x, ...) {
   par(mar = oldpar$mar)
   invisible(x)
 }
+
+#' Converts a foreign object to an osem_measurements data.frame.
+#' @param x A data.frame to attach the class to
+#' @export
+osem_as_measurements = function(x) {
+  ret = as.data.frame(x)
+  class(ret) = c('osem_measurements', class(x))
+  ret
+}
+
+#' @export
+filter_.osem_measurements = dplyr_class_wrapper(osem_as_measurements)
+#' @export
+filter.osem_measurements = dplyr_class_wrapper(osem_as_measurements)
+#' @export
+mutate_.osem_measurements = dplyr_class_wrapper(osem_as_measurements)
+#' @export
+mutate.osem_measurements = dplyr_class_wrapper(osem_as_measurements)
+
+#' maintains class / attributes after subsetting
+#' @noRd
+#' @export
+`[.osem_measurements` = function(x, i, ...) {
+  s = NextMethod('[')
+  mostattributes(s) = attributes(x)
+  s
+}
+

man/osem_as_measurements.Rd

@@ -0,0 +1,14 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/measurement_utils.R
+\name{osem_as_measurements}
+\alias{osem_as_measurements}
+\title{Converts a foreign object to an osem_measurements data.frame.}
+\usage{
+osem_as_measurements(x)
+}
+\arguments{
+\item{x}{A data.frame to attach the class to}
+}
+\description{
+Converts a foreign object to an osem_measurements data.frame.
+}

man/osem_as_sensebox.Rd

@@ -0,0 +1,14 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/box_utils.R
+\name{osem_as_sensebox}
+\alias{osem_as_sensebox}
+\title{Converts a foreign object to an sensebox data.frame.}
+\usage{
+osem_as_sensebox(x)
+}
+\arguments{
+\item{x}{A data.frame to attach the class to}
+}
+\description{
+Converts a foreign object to an sensebox data.frame.
+}

man/osem_as_sf.Rd

@@ -1,5 +1,5 @@
 % Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/utils.R
+% Please edit documentation in R/00utils.R
 \name{osem_as_sf}
 \alias{osem_as_sf}
 \title{Convert a \code{sensebox} or \code{osem_measurements} dataframe to an