[R] data vector to corresonding percentile ranks

[R. Michael Weylandt]

This seems like what you are interested in:

x <- rnorm(50)
ecdf(x)(x)

Michael

On Fri, Dec 23, 2011 at 11:26 AM, Sarah Goslee <sarah.goslee at gmail.com> wrote:
> It's far more useful to send your explanation to the list than it is to send it
> just to me. I've taken the liberty of doing so.
>
> But this does sound like a job for ecdf() - what did you do, and what went
> wrong?
>
> On Fri, Dec 23, 2011 at 12:23 PM, Steven Jones <sjones64 at jhmi.edu> wrote:
>> Actually, what I am trying to do is very simple.  I want to take a large vector of data, about 1.5 million observations and return a corresponding vector of percentiles, each corresponding to the elements of the original data vector in a 1:1 correspondence.
>>
>> Original data vector:      x<--(x1,x2,x3,...xn)
>>                                ^  ^  ^
>>                                |  |  |
>> Derived percentile vector: p<--(p1,p2,p3,...pn)
>>
>> Where pn<--is the percentile value of xn determined from the rank in the data vector x.
>>
>> Ideally, there is a function which could return a vector p from my original data vector x.
>>
>> My understanding, which may be incorrect, is that quantile() function returns the value of x for a specified percentile rank in a vector.
>>
>> Steve
>>
>> -----Original Message-----
>> From: Sarah Goslee [mailto:sarah.goslee at gmail.com]
>> Sent: Friday, December 23, 2011 12:11 PM
>> To: Steven Jones
>> Cc: r-help at r-project.org
>> Subject: Re: [R] data vector to corresonding percentile ranks
>>
>> I'm not sure I understand the question, but does quantile() do what you want?
>>
>> On Fri, Dec 23, 2011 at 10:28 AM, Steve Jones <sjones64 at jhmi.edu> wrote:
>>> I have a problem where I need to calculate the corresponding cohort
>>> percentile ranks for each of several variables.
>>>
>>> Essentially, what I need is a function that will calculate the
>>> distribution-free percentiles from each variable's data vector, returning a
>>> corresponding vector of percentiles:
>>>
>>> e.g.:
>>>
>>> percentile.my.data<-/function/(my.data)
>>>
>>>
>>> I tried to make ecdf() perform this task but was unsuccessful.
>>>
>>> I'd be grateful for any help or advice...
>>>
>>>
>>
>
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