Thanks a lot.
At this point then I wonder: seen that my response consists of 5
outcomes for each set of features, should I then train 5 different
models (one for each of them)?
Cheers
Lorenzo
On Sun, Oct 05, 2014 at 11:04:01AM -0700, Jia Xu wrote:
Hi, Lorenzo:
For 1) I think the formula is not correct. The formula should be outcome
~ features, and that's why you have weird result in 3)
2) predict in caret will automatically find the best result one if
there is one(sometimes it fails). You can print the model to see the cross
validation result. Furthermore, you may specify the performance metric you
want to find the optimal result. Please see the details of the caret
tutorial to see how to.
On Sun, Oct 5, 2014 at 8:54 AM, Lorenzo Isella <lorenzo.ise...@gmail.com>
wrote:
Dear All,
I am learning the ropes of CARET for automatic model training, more or
less following the steps of the tutorial at
http://bit.ly/ZJQINa
However, there are a few things about which I would like a piece of
advice.
Consider for instance the following model
#############################################################
set.seed(825)
fitControl <- trainControl(## 10-fold CV
method = "repeatedcv",
number = 10,
## repeated ten times
repeats = 10)
gbmGrid <- expand.grid(interaction.depth = c(1, 5, 9),
n.trees = (1:30)*50,
shrinkage = 0.05)
nrow(gbmGrid)
gbmFit <- train(Ca+P+pH+SOC+Sand~ ., data = training,
method = "gbm",
trControl = fitControl,
## This last option is actually one
## for gbm() that passes through
verbose = TRUE,
## Now specify the exact models ## to evaludate:
tuneGrid = gbmGrid
)
#############################################################
I am trying to tune a model that predicts the values of 5 columns
whose names are "Ca","P","pH", "SOC", and "Sand".
1) Am I using the formula syntax in a correct way?
I then try to apply my model on the test data by coding
mypred <- predict(gbmFit, newdata=test)
However, at this point I am left with a couple of questions
2) does "predict" automatically select the best tuned model in gbmFit?
and if not, what am I supposed to do?
3) I do not get any error messages, but mypred consists of a single
column instead of 5 columns corresponding to the 5 variables I am
trying to predict, so something is obviously wrong (see point 1). Any
suggestions here?
Many thanks
Lorenzo
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--
Jia Xu
______________________________________________
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and provide commented, minimal, self-contained, reproducible code.