[R] Error in 'Contrasts<-' while using GBM.

[peter dalgaard]

On 30 Nov 2015, at 02:59 , Max Kuhn <mxkuhn at gmail.com> wrote:

> Providing a reproducible example and the results of `sessionInfo` will help
> get your question answered.
> 
> My only guess is that one or more of your predictors are factors and that
> the in-sample data (used to build the model during resampling) have
> different levels than the holdout samples.

Another guess is that there's a factor in your (Karteek's) data that has only one level and that "ID ~ ." is pullling more variables into the model than you actually want. 

-pf

> 
> Max
> 
> On Sat, Nov 28, 2015 at 10:04 PM, Karteek Pradyumna Bulusu <
> kartikpradyumna92 at gmail.com> wrote:
> 
>> Hey,
>> 
>> I was trying to implement Stochastic Gradient Boosting in R. Following is
>> my code in rstudio:
>> 
>> 
>> 
>> library(caret);
>> 
>> library(gbm);
>> 
>> library(plyr);
>> 
>> library(survival);
>> 
>> library(splines);
>> 
>> library(mlbench);
>> 
>> set.seed(35);
>> 
>> stack = read.csv("E:/Semester 3/BDA/PROJECT/Sample_SO.csv", head
>> =TRUE,sep=",");
>> 
>> dim(stack); #displaying dimensions of the dataset
>> 
>> 
>> 
>> #SPLITTING TRAINING AND TESTING SET
>> 
>> totraining <- createDataPartition(stack$ID, p = .6, list = FALSE);
>> 
>> training <- stack[ totraining,]
>> 
>> test <- stack[-totraining,]
>> 
>> 
>> 
>> #PARAMETER SETTING
>> 
>> t_control <- trainControl(method = "cv", number = 10);
>> 
>> 
>> 
>> 
>> 
>> # GLM
>> 
>> start <- proc.time();
>> 
>> 
>> 
>> glm = train(ID ~ ., data = training,
>> 
>>             method = "gbm",
>> 
>>             metric = "ROC",
>> 
>>             trControl = t_control,
>> 
>>             verbose = FALSE)
>> 
>> 
>> 
>> When I am compiling last line, I am getting following error:
>> 
>> 
>> 
>> Error in `contrasts<-`(`*tmp*`, value = contr.funs[1 + isOF[nn]]) :
>> 
>>  contrasts can be applied only to factors with 2 or more levels
>> 
>> 
>> 
>> 
>> 
>> Can anyone tell me where I am going wrong and How to rectify it. It’ll be
>> greatful.
>> 
>> 
>> 
>> Thank you. Looking forward to it.
>> 
>> 
>> 
>> Regards,
>> Karteek Pradyumna Bulusu.
>> 
>>        [[alternative HTML version deleted]]
>> 
>> ______________________________________________
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>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.

-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com