R/findColumn.byname.r

In datana: Datasets and Functions to Accompany Analisis De Datos Con R

#' Sometimes in data manipulation we face the task of locating the position
#' of a specific variable within a dataframe.  The function finds the position
#'  in
#' which a column name is within an object.
#'
#' @details Although the function finds the position of a specific variable,
#' can also
#' be used for more than one variable.
#'
#' @title Finds the position of a specific variable.
#' @param data is a dataframe
#' @param col.name is a string specifying the name of the variable
#'
#' @return This function returns the number of a specific column-name.
#' @author Christian Salas-Eljatib
#' @references
#' Salas-Eljatib, C. 2021. Análisis de datos con el programa estadístico R:
#'  una introducción
#'  aplicada. Ediciones Universidad Mayor, Santiago, Chile. 170 p.
#'  \url{https://eljatib.com/rlibro}
#' @note It can be used for a vector of specified column-names as well.
#' @examples
#'
#' df <- data.frame(varX=1:5, varY=letters[1:5], varZ=rep("a",5),
#' varK=rep("b",5))
#' df
#' #using the function
#' findColumn.byname(df, c("varY","varZ"))
#' findColumn.byname(df, "varK")
#' #Creating an example vector
#' vector <- letters
#' vector
#' findColumn.byname(vector, c("h","z"))
#' @rdname findColumn.byname
#' @export
#'
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
findColumn.byname<-function(data=data,col.name=col.name){
  class.obj <- class(data)
  if(class.obj=="data.frame"){
    output <- which(colnames(data) %in% c(col.name))
    output
  }else{output <- match(col.name,data)
  output}
}