Where is the percentile function in CRAN -R

Question

I do not understand all the terminology inside R. I have only 100 level statistics, trying to learn more.

I am guessing R has a built-in percentile function named something I don't recognize or know how to search for.

I can write my own, but rather use the built in one for obvious reasons.

Here's the one I wrote:

percentile <- function(x) return((x - min(x)) / (max(x) - min(x))

Answer 1

You can do this via

scale(x,center=min(x,na.rm=TRUE),scale=diff(range(x,na.rm=TRUE)))

but I'm not sure there is actually a built-in function that does the scaling you're asking for.

Answer 2

If you are looking to find out specific percentiles from a data set, take a look at the quantile function: ?quantile. By multiplying by 100, you get percentiles.

If you are looking into converting numbers to their percentiles, take a look at rank, though you will need to determine how to address ties. You can simply rescale from rank to quantile by dividing by the length of the vector.

Answer 3

The quantile function might be what you are looking for. If you have vector x and you want to know the 25th, 43rd, and 72nd percentiles you would execute this:

quantile(x, c(.25, .43, .72));

The semicolon is, of course, optional.

See http://www.r-tutor.com/elementary-statistics/numerical-measures/percentile