R/s_dplyr.R

In andrew-edwards/sizeSpectra: Fitting Size Spectra to Ecological Data Using Maximum Likelihood

# Helper functions that allow string arguments for  dplyr's data modification functions like arrange, select etc.
# Author: Sebastian Kranz. Downloaded from
# https://gist.github.com/skranz/9681509 (originally in 2015, downloaded again
# 11th October 2019, hadn't changed). Have edited the comments and added documentation to make package-worthy.
# Only need s_select so commenting out the others.

##' Internal function used by s_filter, s_select etc.
##'
##' Internal functions
##'
##' @param .data input
##' @param .fun.name one of dplyr's functions
##' @param ... other arguments to the the dplyr function
##' @author Sebastian Kranz (https://gist.github.com/skranz/9681509)
eval.string.dplyr = function(.data, .fun.name, ...) {
  args = list(...)
  args = unlist(args)
  code = paste0(.fun.name,"(.data,", paste0(args, collapse=","), ")")
  df = eval(parse(text=code,srcfile=NULL))
  df
}


##' Modified version of dplyr's select that uses string arguments
##'
##' Taken from https://gist.github.com/skranz/9681509 by Sebastian Kranz
##'
##' @param .data input
##' @param ... other arguments to `dplyr::select()`
##' @export
##' @author Sebastian Kranz (https://gist.github.com/skranz/9681509)
s_select = function(.data, ...) {
  eval.string.dplyr(.data,"dplyr::select", ...)
}

# Add dplyr:: everywhere if use others.
# #' Modified version of dplyr's filter that uses string arguments
# #' @export
# #' @param .data
# #' @param ...
# s_filter = function(.data, ...) {
#   eval.string.dplyr(.data,"filter", ...)
# }

# #' Modified version of dplyr's arrange that uses string arguments
# #' @export
# s_arrange = function(.data, ...) {
#   eval.string.dplyr(.data,"arrange", ...)
# }
#
# #' Modified version of dplyr's arrange that uses string arguments
# #' @export
# s_mutate = function(.data, ...) {
#   eval.string.dplyr(.data,"mutate", ...)
# }
#
# #' Modified version of dplyr's summarise that uses string arguments
# #' @export
# s_summarise = function(.data, ...) {
#   eval.string.dplyr(.data,"summarise", ...)
# }
#
# #' Modified version of dplyr's group_by that uses string arguments
# #' @export
# s_group_by = function(.data, ...) {
#   eval.string.dplyr(.data,"group_by", ...)
# }

# Examples
# library(dplyr)

# Original usage of dplyr
#mtcars %.%
# filter(gear == 3,cyl == 8) %.%
# select(mpg, cyl, hp:vs)

# Select user specified cols.
# Note that you can have a vector of strings
# or a single string separated by ',' or a mixture of both
#cols = c("mpg","cyl, hp:vs")
#mtcars %.%
# filter(gear == 3,cyl == 8) %.%
# s_select(cols)

# Filter using a string
#col = "gear"
#mtcars %.%
#  s_filter(paste0(col,"==3"), "cyl==8" ) %.%
#  select(mpg, cyl, hp:vs)

# Arrange without using %.%
#s_arrange(mtcars, "-mpg, gear, carb")

# group_by and summarise with strings
#mtcars %.%
#  s_group_by("cyl") %.%
#  s_summarise("mean(disp), max(disp)")