[R] Adjusting length of series

[David Winsemius]

On Jun 30, 2012, at 8:47 PM, David Winsemius wrote:

>
> On Jun 30, 2012, at 6:04 PM, Lekgatlhamang, lexi Setlhare wrote:
>
>> Hi
>> I have a follow up question, relating to subsetting to list items.  
>> After using the list and min(sapply()) method to adjust the length  
>> of the variables, I specify a dynamic regression equation using the  
>> variables in the list. My list looks like this:
>> Dcr<-  
>> list 
>> (Dcre1 
>> = 
>> DCred1 
>> ,Dcre2 
>> =DCred2,Dcre3=DCred3,Dbobc1=DBoBC1,Dbobc2=DBoBC2,Dbobc3=DBoBC3,...)
>
> This should ahve been done like this:
>
> Dcr<- data.frame(Dcre1=DCred1, Dcre2=DCred2, Dcre3=DCred3,  
> Dbobc1=DBoBC1, Dbobc2=DBoBC2, Dbobc3=DBoBC3)
>
>> By specifying the list items with names, I thought I could end by  
>> referencing them (or subsetting the list) as, eg., Dcr$Dcre1 and  
>> get DCred1, Dcr$Dbobc1 and get DBoBC1, etc so that the explanatory  
>> variables of the equation can be easily associated with their  
>> respective original names. This way, I would avoid specifying the  
>> list as Dcr<-list(Dcr1, Dcr2, Dcr, 3..., Dcr15) and then subsetting  
>> the list using Dcr[[1]][1:29], Dcr[[[2]][1:29], ..., Dcr[[15]] 
>> [1:29] because the list has many variables (15) and referencing the  
>> variables with numbers makes them lose their original names.
>> When I specify the list as Dcr<- list(Dcr1, Dcr2, ..., Dcr15), then  
>> the regression equation specified as:
>> # Regression
>> regCred<- lm(Dcr[[1]][1:29]~Dcr[[2]][1:29]+Dcr[[3]][1:29]+Dcr[[4]] 
>> [1:29]+Dcr[[5]][1:29]+Dcr[[6]][1:29]+...)
>
> And the you could have done
>
>> regCred<- lm(Dcre1 ~ . , data=Dcr [ , 1:29] )

Oh, Nuts! I meant to type:

regCred<- lm(Dcre1 ~ . , data=Dcr [ 1:29, ] )

> (Leaving out the , ...)
>
>
>> runs without problems - the results are shown here below:
>> Call:
>> lm(formula = Dcr[[1]][1:29] ~ Dcr[[2]][1:29] + Dcr[[3]][1:29] +
>> Dcr[[4]][1:29] + Dcr[[5]][1:29] + Dcr[[6]][1:29])
>> Residuals:
>> Min      1Q  Median      3Q     Max
>> -86.293 -33.586  -9.969  40.147 117.965
>> Coefficients:
>> Estimate Std. Error t value Pr(>|t|)
>> (Intercept)    81.02064   13.28632   6.098 3.21e-06 ***
>> Dcr[[2]][1:29] -0.97407    0.11081  -8.791 8.20e-09 ***
>> Dcr[[3]][1:29] -0.27950    0.05899  -4.738 8.95e-05 ***
>> Dcr[[4]][1:29] -0.07961    0.04856  -1.639    0.115
>> Dcr[[5]][1:29] -0.07180    0.05515  -1.302    0.206
>> Dcr[[6]][1:29] -0.01562    0.02086  -0.749    0.462
>>
>> But when I specify the list with names as shown above, then the  
>> equation does not run - as shown by the following error message
>>> # Regression
>>> regCred<- lm(Dcr[[1]][1:29]~Dcr[[2]][1:29]+Dcr[[3]][1:29]+Dcr[[4]] 
>>> [1:29]+
>> + Dcr[[5]][1:29]+Dcr$Dbobc3)
>> Error in model.frame.default(formula = Dcr[[1]][1:29] ~ Dcr[[2]] 
>> [1:29] +  :
>> variable lengths differ (found for 'Dcr$Dbobc3')
>>> Dcr[[5]][1:29]+Dcr$Dbobc3[1:29])
>> Error: unexpected ')' in "Dcr[[5]][1:29]+Dcr$Dbobc3[1:29])"
>>
>> NB: In the equation with error message, only the last term is  
>> specified by referencing its name (ie., Dcr$Dbobc3[1:29]. Also note  
>> that the error occurs whether I append '[1:29]' to Dcr$Dbobc or not.
>> How do I resolve this?
>
This still applies:

You should have offered str(Dcr)

>


David Winsemius, MD
West Hartford, CT