如何使用python根据输入值划分数组

Question

We have the lets say fold value in KNN is N we need to divide the array in N equal part and for each iteration of fold value we need to divide the train and test such way that

example :
fold is 5
1. In First iteration It Consider last means 5th part as test data and rest train data
2. In Second iteration It Consider second last means 4th part as test data and rest train data
3. In third iteration It Consider third last means 3rd part as test data and rest train data
... so on
5. In  Firth iteration It Consider first means 1st part as test data and rest train data

How we can achieve this in Python Can you please explain this .

Answer 1

I think you need the KFold https://scikit-learn.org/stable/modules/generated/sklearn.model_selection.KFold.html

# you can declare number of splits here
kfold = model_selection.KFold(n_splits=5, random_state=42)
# your model goes here. 
model = NearestNeighbors(n_neighbors=2, algorithm='ball_tree')
# this will fit your model 5 times and use 1/5 as test data and 4/5 as training data
results = model_selection.cross_val_score(model, X_train,  y_train, cv=kfold)