[R] Alternative to Scale Function?

[Mark Difford]

>> The scale function will return the mean and sd of the data.

By default. Read ?scale.

Mark.


Noah Silverman-3 wrote:
> 
> I think I just answered my own question.
> 
> The scale function will return the mean and sd of the data.
> 
> So the process is fairly simple.
> scale training data varaible
> note mean and sd from the scale
> then manually scale the test data using the mean and sd from the 
> training data.
> 
> That should make sure that a value is transformed the same regardless of 
> which data set it is in.
> 
> Do I have this correct, or can anybody contribute any more to the concept?
> 
> Thanks!
> 
> 
> --
> Noah
> 
> On 9/11/09 1:10 PM, Noah Silverman wrote:
>> Hi,
>>
>> Is there an alternative to the scale function where I can specify my 
>> own mean and standard deviation?
>>
>> I've come across an interesting issue where this would help.
>>
>> I'm training and testing on completely different sets of data.  The 
>> testing set is smaller than the training set.
>>
>> Using the standard scale function of R seems to introduce some error.  
>> Since it scales data WITHIN the set, it may scale the same number to 
>> different value since the range in the training and testing set may be 
>> different.
>>
>> My thought was to scale the larger training set of data, then use the 
>> mean and SD of the training data to scale the testing data according 
>> to the same parameters.  That way a number will transform to the same 
>> result regardless of whether it is in the training or testing set.
>>
>> I can't be the first one to have looked at this.  Does anyone know of 
>> a function in R or if there is a scale alternative where I can control 
>> the parameters?
>>
>> Thanks!
>>
>> -- 
>> Noah
>>
>> ______________________________________________
>> R-help at 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.
> 
> ______________________________________________
> R-help at 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.
> 
> 

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