How to write a function that coverts temperatures in F, C, and K?-CodePudding

I am attempting to create a function called temperatureConverter, which will be a one-stop shop for converting any temperature between F, C or K. Ultimately, it should work something like this:

newTemp=temperatureConverter(57,from="C",to="K")

I understand that several if-then-else statements are needed, and that I should have default values of "C" for from, and "F" for to. I just don't know how to code for this.

The following is what I have tried (see two attached screenshots). I think there's something wrong with my temperature converter function.

enter image description here enter image description here

CodePudding user response：

Next time, please paste in the actual code, rather than posting a picture of the code. All of your functions like cToF seem okay, but there's no need to assign the desired output to a variable, but if you do, then put that variable (c or whatever) on the last line of the function.

Your main problem is that you want something like

temperatureConverter <- function(input, from="C",to="K"){
  if (from == "C" & to =="K") {
    cTok(input)
  } else ...

Note the double == for checking equality inside the if.

CodePudding user response：

# Temperature converter

temp_convert <- function(x, from = "C", to = "F"){
    
    Celcius <- c('c', 'C', 'Celcius', 'celcius')
    Fahrenheit <- c('f', 'F', 'Fahrenheit', 'fahrenheit')
    Kelvin <- c('k', 'K', 'Kelvin', 'kelvin')
    all <- c(Celcius, Fahrenheit, Kelvin)
    
    # ------------------------ Handle exceptions -------------------
    if (!(from %in% all) | !(to %in% all)){
        x_ <- NA
        warning("Please key-in appropriate units, exp. C, F, K ...")
    }
    
    if (from == to){
        x_ <- x
        warning("Nothing change")
    }
    
    if (is.null(from) | is.null(to)){
        x_ <- x
        warning("Both the 'from' and 'to' args must be provided")
    }
    
    # ---------------------- Convert from Celcius ------------------
    if (from %in% Celcius){
        if (to %in% Fahrenheit)
            x_ <- x * (9 / 5)   32
        if (to %in% Kelvin)
            x_ <- x   273.15
    }
    
    # --------------------- Convert from Fahrenheit ----------------
    if (from %in% Fahrenheit){
        if (to %in% Celcius)
            x_ <- (x - 32) * (5 / 9)
        if (to %in% Kelvin)
            x_ <- (x - 32) * (5 / 9)   273.15
    }
    
    # ----------------------- Convert from Kelvin ------------------
    if (from %in% Kelvin){
        if (to %in% Celcius)
            x_ <- x - 273.15
        if (to %in% Kelvin)
            x_ <- (x - 273.15) * (9 / 5)   32
    }
    
    return(x_)
}

Console:

> temp_convert(20, from = "celcius", to = "F")
[1] 68

> temp_convert(20, from = "k", to = "c")
[1] -253.15

> temp_convert(20, from = "F", to = "F")
[1] 20
Warning message:
In temp_convert(20, from = "F", to = "F") : Nothing change

> temp_convert(20, from = "b", to = "F")
[1] NA
Warning message:
In temp_convert(20, from = "b", to = "F") :
  Please key-in appropriate units, exp. C, F, K ...