#' Function that checks whether a set of columns given as a vector of strings is in a data frame and, if not, gives feedback on
#' which are missing before stopping execution of the program.
#'
#' @param requiredCols A character vector containg the names of columns the presence of which in a data frame is to be verfied
#' @param dfName Name of the data frame in which the columns in requiredCols are to be found
#' @param specifiedIn An optional argument (default) that allows the output to detail where the varaible names can be changed by the user
#' @return TRUE, unless it stopped
#Florian Lorenz, 2014
checkDfCols <- function(requiredCols, dfName, specifiedIn="which was specified in preferences"){
if( !all( requiredCols %in% colnames(dfName) ) ){
for( rc in length(requiredCols) ){
if ( !( requiredCols[rc] %in% colnames(dfName) ) ){
stop(paste("Required variable ", requiredCols[rc], specifiedIn, " is not in input data.",sep=""))
}
}
}
return(TRUE)
}
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