# [R] How to rank matrix data by deciles?

Peter Ehlers ehlers at ucalgary.ca
Sun May 16 10:21:36 CEST 2010

```On 2010-05-13 17:50, Phil Spector wrote:
> Vincent -
> I'm afraid there's no solution other than artificially modifying
> the zeroes:
>
>> vec
> [1] 26.58950617 5.73074074 5.96222222 5.64777778 20.95728395 0.00000000
> 0.07000000 12.86888889
> [9] 3.64543210 0.05049383 25.60888889 3.53246914 0.00000000 31.39049383
> 3.77641975 13.19617284
> [17] 0.00000000
>> cut(vec,quantile(vec,(0:10)/10),include.lowest=TRUE,label=FALSE)
> Error in cut.default(vec, quantile(vec, (0:10)/10), include.lowest =
> TRUE, :
> 'breaks' are not unique
>> vec[vec==0] = jitter(vec[vec==0])
>> cut(vec,quantile(vec,(0:10)/10),include.lowest=TRUE,label=FALSE)
> [1] 10 6 7 5 9 1 3 7 4 2 9 4 2 10 5 8 1
>
> It gives an answer, but it may not make sense for all data.
>
> - Phil
>

The problem is that quantile() produces multiple values
for the breaks used in cut(). Phil's suggestion modifies
the data. It might be preferable to modify the breaks:

eps <- .Machine\$double.eps  #or use something like 1e-10
brks <- quantile(vec, (0:10)/10) + eps*(0:10)
cut(vec, brks, include.lowest=TRUE, labels=FALSE)
#[1] 10  6  7  5  9  1  3  7  4  2  9  4  1 10  5  8  1

-Peter Ehlers

> On Thu, 13 May 2010, vincent.deluard wrote:
>
>>
>>
>>
>> Dear Phil,
>>
>> You helped me with a request to rand matrix columns by deciles two weeks
>> ago.
>>
>> This really un-blocked me on this project but I found a little bug.
>>
>> As in before, my data is in a matrix:
>>
>> X4.19.2010 X4.16.2010
>> [1,] 26.61197531 26.58950617
>> [2,] 5.72765432 5.73074074
>> [3,] 5.95839506 5.96222222
>> [4,] 5.64333333 5.64777778
>> [5,] 20.93814815 20.95728395
>> [6,] 0.00000000 0.00000000
>> [7,] 0.07000000 0.07000000
>> [8,] 12.87802469 12.86888889
>> [9,] 3.64407407 3.64543210
>> [10,] 0.05037037 0.05049383
>> [11,] 25.59024691 25.60888889
>> [12,] 3.47987654 3.53246914
>> [13,] 0.00000000 0.00000000
>> [14,] 31.39037037 31.39049383
>> [15,] 3.78296296 3.77641975
>> [16,] 13.17876543 13.19617284
>>
>> The apply function will work for this sample of my data:
>>
>> cut(x,quantile(x,(0:10)/10,
>> na.rm=TRUE),label=FALSE,include.lowest=TRUE))
>>
>> debtdeciles
>>
>> X4.19.2010 X4.16.2010
>> [1,] 10 10
>> [2,] 6 6
>> [3,] 6 6
>> [4,] 5 5
>> [5,] 8 8
>> [6,] 1 1
>> [7,] 2 2
>> [8,] 7 7
>> [9,] 4 4
>> [10,] 2 2
>> [11,] 9 9
>> [12,] 3 3
>> [13,] 1 1
>> [14,] 10 10
>> [15,] 4 4
>> [16,] 8 8
>>
>> However, it will fail for
>>
>> X4.19.2010 X4.16.2010
>> [1,] 26.61197531 26.58950617
>> [2,] 5.72765432 5.73074074
>> [3,] 5.95839506 5.96222222
>> [4,] 5.64333333 5.64777778
>> [5,] 20.93814815 20.95728395
>> [6,] 0.00000000 0.00000000
>> [7,] 0.07000000 0.07000000
>> [8,] 12.87802469 12.86888889
>> [9,] 3.64407407 3.64543210
>> [10,] 0.05037037 0.05049383
>> [11,] 25.59024691 25.60888889
>> [12,] 3.47987654 3.53246914
>> [13,] 0.00000000 0.00000000
>> [14,] 31.39037037 31.39049383
>> [15,] 3.78296296 3.77641975
>> [16,] 13.17876543 13.19617284
>> [17,] 0.00000000 0.00000000
>>
>>
>> + cut(x,quantile(x,(0:10)/10,
>> na.rm=TRUE),label=FALSE,include.lowest=TRUE))
>> Error in cut.default(x, quantile(x, (0:10)/10, na.rm = TRUE), label =
>> FALSE,
>> :
>> 'breaks' are not unique
>>
>> My guess is that we now have 3 "zeros" in each column. For each
>> decile, we
>> cannot have more than 2 elements (total of 17 numbers in each column)
>> and I
>> believe R cannot determine where to put the third "zero". Do you have any
>> solution for this problem?
>>
>> Many thanks,
>>
>> --
>> View this message in context:
>> http://r.789695.n4.nabble.com/How-to-rank-matrix-data-by-deciles-tp2133496p2215945.html
>>
>> Sent from the R help mailing list archive at Nabble.com.
>>

```