what is knnfit? is there a way to select variables in r r knn how to select variable what is r variable selection r how to select all variable what is the knn model what type of model is knn? r what is the model for each variable used how many variables are used in r for data r calculate knn variable r how to select knn variable r find a variable in a train function how to use knntrain function how to set variable selection r r is knn model only used for model what is the difference between knnfit and knnfit knn r model what variables to use knn model number of variables how to use knn in linear regression when knnfit a variable which is used