Error message for user-defined r function to change class of data frame columns-CodePudding

Apologies in advance as my understanding of user-defined functions in R is very limited (I've never been quite able to figure them out).

Basically, I would like to define a function that changes the class of my columns in the data frame. I have written the following code:

correct_var_types_func = function(data){
  data[["Accident ID"]] = as.integer(data[["Accident ID"]])
  data[["Accident Year"]] = as.integer(data[["Accident Year"]])
  data[["City"]] = as.character(data[["City"]])
  data[["Total Fatalities"]] = as.integer(data[["Total Fatalities"]])
  data[["Total Number Injured"]] = as.integer(data[["Total Number Injured"]])
  data[["Bicyclist Injuries"]] = as.integer(data[["Bicyclist Injuries"]])
  data[["Bicyclist Fatalities"]] = as.integer(data[["Bicyclist Fatalities"]])
  data[["Longitude"]] = as.numeric(data[["Longitude"]])
  data[["Latitude"]] = as.numeric(data[["Latitide"]])
 
}

correct_var_types_func(test_data)

Running this code gives an error message Error in `[[<-.data.frame`(`*tmp*`, "Latitude", value = numeric(0)) : replacement has 0 rows, data has 50

I tried running the function again with the dataframe in quotes correct_var_types_function("test_data"), but this gave me an error as well.

The test_data dataframe is in my global environment. I have had similar issues with functions in the past and I am not quite sure how to resolve this so that the function does what I need it to do.

Thank you very much!

test_data = structure(list(`Accident ID` = c(6343597L, 6343740L, 6343743L, 
6343752L, 6343831L, 6343846L, 6343870L, 6343900L, 6349938L, 6350439L, 
6350519L, 6350521L, 6350552L, 6350558L, 6350562L, 6350596L, 6350598L, 
6350629L, 6354470L, 6354480L), `Accident Year` = c("2011", "2011", 
"2011", "2011", "2011", "2011", "2011", "2011", "2011", "2011", 
"2011", "2011", "2011", "2011", "2011", "2011", "2011", "2011", 
"2011", "2011"), City = c("Champaign-Urbana", "Champaign-Urbana", 
"Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", 
"Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", 
"Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", 
"Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", "Champaign-Urbana", 
"Champaign-Urbana", "Champaign-Urbana"), `Total Fatalities` = c("0", 
"0", "0", "0", "0", "0", "0", "1", "0", "0", "0", "0", "0", "0", 
"0", "0", "0", "0", "0", "0"), `Total Number Injured` = c("0", 
"1", "0", "0", "0", "0", "0", "0", "0", "0", "1", "0", "1", "3", 
"0", "1", "0", "0", "2", "0"), `Bicyclist Injuries` = c(0, 0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), `Bicyclist Fatalities` = c(0, 
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), Latitude = c("40.1102285458875", 
"40.0981104733762", "40.0980895305079", "40.0981499831071", "40.1080218304802", 
"40.1124497904284", "40.1314437866789", "40.132399221271", "40.074148834686", 
"40.3168001708079", "39.9812000296446", "40.1192502269937", "40.024754913885", 
"39.8986645952302", "40.1166326222204", "40.1360830131773", "40.0980934386924", 
"40.3790963986935", "40.127649987084", "40.138010298808"), Longitude = c("-88.2421", 
"-88.252", "-88.2467", "-88.2576", "-88.2963", "-88.205", "-88.197", 
"-88.1966", "-88.2484", "-88.1833", "-88.2375", "-88.2469", "-88.256", 
"-88.2707", "-88.2435", "-88.258", "-88.2446", "-87.9508", "-88.3001", 
"-88.2389")), row.names = c(NA, 20L), class = "data.frame")

CodePudding user response：

Typo in my code...it runs correctly now. Thanks!

CodePudding user response：

A recommendation tangential to the typo: this might be a more robust function:

correct_var_types_func <- function(data) {
  chr <- intersect(colnames(data),
                   c("City"))
  int <- intersect(colnames(data),
                   c("Accident ID", "Accident Year", "Total Fatalities",
                     "Total Number Injured", "Bicyclist Injuries", "Bicyclist Fatalities"))
  num <- intersect(colnames(data),
                   c("Longitude", "Latitude"))
  missed <- setdiff(c(chr, int, num), colnames(data))
  if (length(missed)) {
    warning("missing column names: ",
            paste(sQuote(missed, FALSE), collapse = ", "))
  }
  data[,chr] <- lapply(data[,chr,drop=FALSE], as.character)
  data[,int] <- lapply(data[,int,drop=FALSE], as.character)
  data[,num] <- lapply(data[,num,drop=FALSE], as.character)
  data
}