Fitting a quadratic curve for each data set that has different lengths

问题

I would like to fit a quadratic to (Time,SkinTemp) for each id in the following data.frame df. Each id has a different number of Time,SkinTemp entries so I'm stuck with 'predict'

df<-data.frame(Time=seq(65),
               SkinTemp=rnorm(65,37,0.5),
               id=rep(1:10,c(5,4,10,6,7,8,9,8,4,4)))

So far I have:

#Fit the model y=x^2+x+C
fitted_models = df %>% group_by(id) %>% do(model = lm(SkinTemp ~ Time+I(Time^2), data = .))

So far so good. Here's where I'm stuck. How do I pass the original Time data into the predict function below?

#Predict data points for each quadratic 
predQ<-sapply(unique(df$id), function(x) predict(fitted_models$model[[x]]))

回答1:

Use fitted:

lapply(fitted_models$model, fitted)

来源：https://stackoverflow.com/questions/48687685/fitting-a-quadratic-curve-for-each-data-set-that-has-different-lengths