用R中的模型预测结果

Question

I am trying to do a simple prediction, using linear regression I have a data.frame where some of the items are missing price (and therefor noted NA). This apperantely doesn't work:

#Simple LR
fit <- lm(Price ~ Par1 + Par2 + Par3, data=combi[!is.na(combi$Price),])
Prediction <- predict(fit,  data=combi[is.na(combi$Price),]), OOB=TRUE, type = "response")

What should I put instead of data=combi[is.na(combi$Price),]) ?

Answer 1

Change data to newdata . Look at ?predict.lm to see what arguments predict can take. Additional arguments are ignored. So in your case data (and OOB ) is ignored and the default is to return predictions on the training data.

Prediction <- predict(fit, newdata = combi[is.na(combi$Price),])

identical(predict(fit), predict(fit, data = combi[is.na(combi$Price),]))
## [1] TRUE