R help - Feb 2009 - Re place Values within vector using Translation vector

Dear everyone 
I would like to change values in vectors doing a translation. i.e. I have a
start vector giving me the levels in one vector (numbers 1 to x - rating)
and then I have a second vector giving me the values to be allocated (loss
probabilities), but the number of potential rating classes and loss
estimates is still subject to a lot of discussion.

Attached a simplified version of the problem (original has more values and
needs to stay flexible, i.e. length of translation vector can change.

Trans_Prob_values<-c(0.005, 0.01, 0.1)
Trans_CR<-c(1,2,3)
a<-c(3,2,1,1,2,3)
A<-replace(a, Trans_CR, Trans_Prob_values)
A

This however produces
[1] 0.005 0.010 0.100 1.000 2.000 3.000
as opposed to the desired result.


The help however says 
"replace replaces the values in x with indexes given in list by those given
in values. If necessary, the values in values are recycled. " which in my
view should be exactly doing the job intended above.

Constructions with nested ifelse statements and individual replacements are
too cumbersome in my view.
I searched for conditional replacement, vector replace, replace function and
read the problems, but generally they have conditions like age>30 then x,
not a direct translation of values.

If anyone has an idea, please do share it.
Thanks
Christian

-- 
View this message in context:
http://www.nabble.com/Replace-Values-within-vector-using-Translation-vector-tp22088527p22088527.html
Sent from the R help mailing list archive at Nabble.com.

On 18/02/2009 4:24 PM, Christian Langkamp wrote:
> Dear everyone 
> I would like to change values in vectors doing a translation. i.e. I have a
> start vector giving me the levels in one vector (numbers 1 to x - rating)
> and then I have a second vector giving me the values to be allocated (loss
> probabilities), but the number of potential rating classes and loss
> estimates is still subject to a lot of discussion.
> 
> Attached a simplified version of the problem (original has more values and
> needs to stay flexible, i.e. length of translation vector can change.
> 
> Trans_Prob_values<-c(0.005, 0.01, 0.1)
> Trans_CR<-c(1,2,3)
> a<-c(3,2,1,1,2,3)
> A<-replace(a, Trans_CR, Trans_Prob_values)
> A
> 
> This however produces
> [1] 0.005 0.010 0.100 1.000 2.000 3.000
> as opposed to the desired result.
> 
> 
> The help however says 
> "replace replaces the values in x with indexes given in list
Since your Trans_CR contains 1:3, this says the first 3 entries of x 
will be replaced, and that's what happened.

What you want is simply

A <- Trans_Prob_values[a]

(assuming that the indices are always in 1:x, and that Trans_Prob_values 
will have x values in it).

Duncan Murdoch


  by those given
> in values. If necessary, the values in values are recycled. " which in
my
> view should be exactly doing the job intended above.
> 
> Constructions with nested ifelse statements and individual replacements are
> too cumbersome in my view.
> I searched for conditional replacement, vector replace, replace function
and
> read the problems, but generally they have conditions like age>30 then
x,
> not a direct translation of values.
> 
> If anyone has an idea, please do share it.
> Thanks
> Christian
>

The call to replace is replacing the 1st 3 elements of a (your indexes in
Trans_CR) with the values and leaving the 4-6 elements alone.  For what you
want, try:

A <- Trans_Prob_values[ match(a, Trans_CR) ]

Hope this helps,


-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Christian Langkamp
> Sent: Wednesday, February 18, 2009 2:25 PM
> To: r-help at r-project.org
> Subject: [R] Re place Values within vector using Translation vector
> 
> 
> Dear everyone
> I would like to change values in vectors doing a translation. i.e. I
> have a
> start vector giving me the levels in one vector (numbers 1 to x -
> rating)
> and then I have a second vector giving me the values to be allocated
> (loss
> probabilities), but the number of potential rating classes and loss
> estimates is still subject to a lot of discussion.
> 
> Attached a simplified version of the problem (original has more values
> and
> needs to stay flexible, i.e. length of translation vector can change.
> 
> Trans_Prob_values<-c(0.005, 0.01, 0.1)
> Trans_CR<-c(1,2,3)
> a<-c(3,2,1,1,2,3)
> A<-replace(a, Trans_CR, Trans_Prob_values)
> A
> 
> This however produces
> [1] 0.005 0.010 0.100 1.000 2.000 3.000
> as opposed to the desired result.
> 
> 
> The help however says
> "replace replaces the values in x with indexes given in list by those
> given
> in values. If necessary, the values in values are recycled. " which in
> my
> view should be exactly doing the job intended above.
> 
> Constructions with nested ifelse statements and individual replacements
> are
> too cumbersome in my view.
> I searched for conditional replacement, vector replace, replace
> function and
> read the problems, but generally they have conditions like age>30 then
> x,
> not a direct translation of values.
> 
> If anyone has an idea, please do share it.
> Thanks
> Christian
> 
> --
> View this message in context: http://www.nabble.com/Replace-Values-
> within-vector-using-Translation-vector-tp22088527p22088527.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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