Sorry, I meant to put that it didn't work for "GM", not "Toyota".

> DF[DF$Company=="GM",]
   Company Person    Salary rank
1       GM      A  7067.905    4
3       GM      C 31627.171    8
5       GM      E 66200.508    7
7       GM      G 91287.592    3
10      GM      J 33239.467    6
13      GM      M 47854.525    5
14      GM      N 76631.067    2
16      GM      P 87532.133    1

In this data, person "G" earned 91287, but has rank 3 even though this is
the highest salary in this partition.  The lowest salary earned is the 7067
by person "A", so this should have rank = 8, but in fact this gives rank =
4.

Is that more clear?

Thanks,
Brigid



On Fri, Jun 1, 2012 at 1:48 PM, arun <smartpink111@yahoo.com> wrote:

> Hi,
>
> Couldn't find any problems if I understand what you mean.
>
> A.K.
>
>
>
> > DF <-within(DF,rank<-ave(Salary,Company,FUN=function(x)rev(order(x))))
> > DF
>    Company Person    Salary rank
> 1       GM      A  7067.905    4
> 2     Ford      B  9946.616    3
> 3       GM      C 31627.171    8
> 4   Toyota      D 51863.426    1
> 5       GM      E 66200.508    7
> 6   Toyota      F 40683.019    4
> 7       GM      G 91287.592    3
> 8   Toyota      H 29360.337    2
> 9   Toyota      I 45906.573    7
> 10      GM      J 33239.467    6
> 11    Ford      K 65087.047    2
> 12  Toyota      L 25801.678    3
> 13      GM      M 47854.525    5
> 14      GM      N 76631.067    2
> 15  Toyota      O  8424.691    5
> 16      GM      P 87532.133    1
> 17  Toyota      Q 33907.294    6
> 18    Ford      R 83944.035    1
> > DF[DF$Company=="Ford",]
>    Company Person    Salary rank
> 2     Ford      B  9946.616    3
> 11    Ford      K 65087.047    2
> 18    Ford      R 83944.035    1
> > DF[DF$Company=="Toyota",]
>    Company Person    Salary rank
> 4   Toyota      D 51863.426    1
> 6   Toyota      F 40683.019    4
> 8   Toyota      H 29360.337    2
> 9   Toyota      I 45906.573    7
> 12  Toyota      L 25801.678    3
> 15  Toyota      O  8424.691    5
> 17  Toyota      Q 33907.294    6
> > DF[DF$Company=="GM",]
>    Company Person    Salary rank
> 1       GM      A  7067.905    4
> 3       GM      C 31627.171    8
> 5       GM      E 66200.508    7
> 7       GM      G 91287.592    3
> 10      GM      J 33239.467    6
> 13      GM      M 47854.525    5
> 14      GM      N 76631.067    2
> 16      GM      P 87532.133    1
>
>
>
>
> ----- Original Message -----
> From: Brigid Mooney <bkmooney@gmail.com>
> To: r-help@r-project.org
> Cc:
> Sent: Friday, June 1, 2012 11:23 AM
> Subject: [R] Add rank column to data frame as in SQL...
>
> Hopefully this is an easy problem...
>
> I'm trying to add a partitioned rank column to a data frame where the
> rank is calculated separately across a partition by categories, the
> way you could easily do in SQL.  I found this solution in the archives
> that looked like it might work:
>
> http://tolstoy.newcastle.edu.au/R/e11/help/10/09/8675.html
>
> The example has a data frame with several car companies, and employee
> salaries within them.  A column is then added to the data.frame which
> should give the descending rank for each employee, partitioned by
> company.
>
>
> But when I implemented it, the results weren't the expected rankings.
> What am I doing wrong?
>
> set.seed(1)
> DF <-
> data.frame(Company=sample(c("Ford","Toyota","GM"),size=18,replace=TRUE),
> Person=LETTERS[1:18],Salary=runif(18)*1e5)
> DF <- within(DF, rank <- ave(Salary, Company,
> FUN=function(x)rev(order(x))))
>
> # Then checking each category manually
> DF[DF$Company == "Ford",]
> DF[DF$Company == "GM",]
> DF[DF$Company == "Toyota",]
>
> # My results show that it works for Ford and GM, but not Toyota
> > DF[DF$Company == "Ford",]
>    Company Person   Salary rank
> 1     Ford      A 38003.52    4
> 5     Ford      E 65167.38    2
> 10    Ford      J 38238.80    3
> 11    Ford      K 86969.08    1
> 12    Ford      L 34034.90    5
> > DF[DF$Company == "GM",]
>    Company Person   Salary rank
> 4       GM      D 21214.25    6
> 6       GM      F 12555.51    7
> 7       GM      G 26722.07    5
> 13      GM      M 48208.01    4
> 15      GM      O 49354.13    3
> 17      GM      Q 82737.33    1
> 18      GM      R 66846.67    2
> > DF[DF$Company == "Toyota",]
>    Company Person    Salary rank
> 2   Toyota      B 77744.522    2
> 3   Toyota      C 93470.523    1
> 8   Toyota      H 38611.409    5
> 9   Toyota      I  1339.033    3
> 14  Toyota      N 59956.583    6
> 16  Toyota      P 18621.760    4
>
>
> For reference, I'm using R 2.11.1 on a Windows 7 machine.
>
> Can anyone provide insight into how I am implementing this
> incorrectly, or give an alternate way to add such a partitioned rank
> column to a data frame?
>
> Thanks in advance,
> Brigid
>
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