Function for converting dataframe column type

R often understands data frame columns in a "wrong" format or you just have to change the column class from factor to character in order to modify it. I have been changing the column class in following way previously: ``` set.seed(1) df <- data.frame(x = 1:10, y = rep(1:2, 5), k = rnorm(10, 5,2), z = rep(c(2010, 2012, 2011, 2010, 1999), 2), j = c(rep(c("a", "b", "c"), 3), "d")) x <- c("y", "z") for(i in 1:length(x)){ df[,x[i]] <- factor(df[,x[i]])} ``` And back to numeric: ``` x <- 1:5 for(i in 1:length(x)){ df[,x[i]] <- as.numeric(as.character(df[,x[i]]))} # Character cannot become numeric ``` It occurred to me that maybe there is a better way doing this. I found this question, which is almost exactly what I need: ``` convert.magic <- function(obj,types){ out <- lapply(1:length(obj),FUN = function(i){FUN1 <- switch(types[i], character = as.character, numeric = as.numeric, factor = as.factor); FUN1(obj[,i])}) names(out) <- colnames(obj) as.data.frame(out) } ``` However, for this function vector type has to be specified for each column: ``` convert.magic(df, rep("factor",5)) convert.magic(df, c("character", "factor")) # Error in FUN(1:5[[1L]], ...) : could not find function "FUN1" ``` Could somebody help me and rebuild this function so that it works with column names and numbers, please? I am afraid that this would be too advanced for me... ``` x <- c("y", "z") convert.magic(df, "character", x) ```