How to update trainSet on each iteration

[Raj]

I run the code successfully,
runfile('D:/Mekala_Backupdata/PythonCodes/randonForest_SVR.py', wdir='D:/Mekala_Backupdata/PythonCodes')
Linear SVM
Accuracy: 0.25
1) x3 0.000000
2) x1 0.000000
3) x2 0.000000
RandonForest
Accuracy: 0.25
1) x2 0.405015
2) x1 0.310160
3) x3 0.284826

But my following question:

My initial Train set is 90% and test set is 10%, I want to update the train set on each iteration like:
if my total data set is 10, initial trainset size is 7(1~7), I predict 8,9,10. When I predict 8th one, then my train set will become 8(1~8) to predict 9, then after predicting 9th one, the train set will update to 1~9, and predict 10th one