Hello Kai

This looks like a fun question.

Here is my solution, I'd be curious to see solutions by other people here.
It can also be tweaked in various ways, and easily put into a function
(actually, if you do it - please put it back online :) )
The only thing that might require some work is the rearranging of the
columns.

Cheers,
Tal



######################
# Loading the functions
######################
# Making sure we can source code from github
source("
http://www.r-statistics.com/wp-content/uploads/2012/01/source_https.r.txt")
# This is based on code first discussed here:
##
http://www.r-statistics.com/2012/01/printing-nested-tables-in-r-bridging-between-the-reshape-and-tables-packages/

# Reading in the function for using merge that reserves order
source_https("
https://raw.github.com/talgalili/R-code-snippets/master/merge.data.frame.r")




##################
# Make Data
knames <-c('ab', 'aa', 'ac', 'ad', 'ab', 'ac', 'aa', 'ad','ae', 'af')
kdate <- as.Date( c('20111001', '20111102', '20101001', '20100315',
'20101201', '20110105', '20101001', '20110504', '20110603', '20110201'),
format="%Y%m%d")
kdata <- data.frame (knames, kdate)
kdata$kdate <- as.character(kdata$kdate)

##################
# Calculate counts
tmp <- data.frame(table(kdata$kdate))
colnames(tmp)[1] <- "kdate"
tmp[,1] <- as.character(tmp[,1])

# Based on this:
#
http://www.r-statistics.com/2012/01/merging-two-data-frame-objects-while-preserving-the-rows-order/
merge.data.frame(kdata ,tmp ,keep_order = "x")

### Solution:
         kdate knames Freq
9  2011-10-01     ab    1
10 2011-11-02     aa    1
2  2010-10-01     ac    2
1  2010-03-15     ad    1
4  2010-12-01     ab    1
5  2011-01-05     ac    1
3  2010-10-01     aa    2
7  2011-05-04     ad    1
8  2011-06-03     ae    1
6  2011-02-01     af    1






----------------Contact
Details:-------------------------------------------------------
Contact me: Tal.Galili@gmail.com |  972-52-7275845
Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) |
www.r-statistics.com (English)
----------------------------------------------------------------------------------------------




On Sat, Feb 11, 2012 at 8:17 PM, Kai Mx <govokai@gmail.com> wrote:

> Hi everybody,
> I have a large dataframe similar to this one:
> knames <-c('ab', 'aa', 'ac', 'ad', 'ab', 'ac', 'aa', 'ad','ae', 'af')
> kdate <- as.Date( c('20111001', '20111102', '20101001', '20100315',
> '20101201', '20110105', '20101001', '20110504', '20110603', '20110201'),
> format="%Y%m%d")
> kdata <- data.frame (knames, kdate)
> I would like to add a new variable to the dataframe counting the
> occurrences of different values in knames in their order of appearance
> (according to the date as in indicated in kdate). The solution should be a
> variable with the values 2,2,1,1,1,2,1,2,1,1. I could do it with a loop,
> but there must be a more elegant way to this.
>
> Thanks!
>
> Best,
>
> Kai
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

	[[alternative HTML version deleted]]

