Why is my custom function not working correct for converting longitude and latitude?

Question

I wrote a code to convert a decimal value into long/lat coordinates and it works well for my latitude values but not my longitude values. It is not rounding to the correct decimal place. Here is my function:

convert.lon <- function(x){
  #degress
  d <- as.character(x)
  d <- str_sub(string = d, start = 1, end = 2)
  deg <- d
  
  #minutes 
  m <- x - as.numeric(d)
  m <- m*60
  m <- str_sub(string = as.character(m), start = 1, end = 2)
  min <- m
  
  #seconds
  m <- x - as.numeric(d)
  m <- m*60
  s <- m - as.numeric(min)
  s <- round(x=s*60, digits = 4)
  sec <- as.character(s)
  
  #cardinal direction 
  dir <- ifelse(test = x>0, yes = 'E', no= 'W')
  
  #paste together with symbols
  output <- paste0(deg, "º ", min, "' ", sec, '" ', dir)
  noquote(output)
  return(output)
}

Here are some example beginning values:

start.patch.lon
-79.40056
-79.39279

and here are the values it returns:

start.lon
-7º -4' -260402.0253" W
-7º -4' -260374.038" W

But I would like it to look like this:

start.lon
-7º -4' -26.0402" W
-7º -4' -26.0374" W

Answer 1

You could do:

convert.lon <- function(x){
  #degress
  d <- as.character(x)
  d <- str_sub(string = d, start = 1, end = 2)
  deg <- d
  
  #minutes 
  m <- x - as.numeric(d)
  m <- m*60
  m <- str_sub(string = as.character(m), start = 1, end = 2)
  min <- m
  
  #seconds
  m <- x - as.numeric(d)
  m <- m*60
  s <- m - as.numeric(min)
  s <- round(x=s*60/10000, digits = 4)
  sec <- as.character(s)
  
  #cardinal direction 
  dir <- ifelse(test = x>0, yes = 'E', no= 'W')
  
  #paste together with symbols
  output <- paste0(deg, "º ", min, "' ", sec, '" ', dir)
  output <- noquote(output)
  return(output)
}

So that:

convert.lon(-79.39279)
#> [1] -7º -4' -26.0374" W