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Reformatting numeric values ​​without coercing a character

Let's take the following vector x

.

x <- c(50.333, 195.333, 186, 214.333, 246.667)

Decimal numbers x

will always be zero, 1/3, or 2/3 (i.e. 0.0, 0.333, or 0.667). I would like to quickly change their corresponding decimal places to the result of the following

> round(x %% 1/3, 1)
[1] 0.1 0.1 0.0 0.1 0.2

means that for x

  • if 0 is decimal it is still zero
  • if 0.333 is decimal it changes by 0.1
  • if 0.667 is decimal, it changes by 0.2

Currently I am clunkily converting to character and then reverting back to numeric to get the next desired result ...

> as.numeric(paste0(round(x, 0), sub("0", "", round(x %% 1/3, 1))))
[1]  50.1 195.1 186.0 214.1 247.2

Is there a mathematical way to do this without forcing the character?

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2 answers


I built on your previous efforts and got good results:



x <- c(50.333, 195.333, 186, 214.333, 246.667)

stripDecimal <- function(x){
  y <- as.integer(x)
  z <- round(x %% 1/3, 1)
  y+z
}

stripDecimal(x)
[1]  50.1 195.1 186.0 214.1 246.2
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Why not just get the fraction for each number and divide it by .333 (round up), then divide by 10 to get the converted number you want. Mathematically:

  • intpart = floor (number);
  • fracpart = number -intpart
  • newfracpart = (fracpart / .333)
  • new number = intpart + newfracpart / 10.0


I'm not sure why you want to encode your numbers this way ... any specific reason?

You might want to change the number to "number of thirds" and use modulo 3 to get the fractional part and number / 3 for int

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