[R] Grouping variables in a data frame

[Andra Isan]

Hi All, 

I have a data frame as follow:

user_id time age location gender 
.....

and I learn a logistic regression to learn the weights (glm with family= (link = logit))), my response value is either zero or one. I would like to group the users based on user_id and time and see the y values and predicted y values at the same time. Or plot them some how. Is there any way to somehow group them together so that I can learn more about my data by grouping them?

I would like to get these at the end
user_id time y predicted_y

Thanks a lot,
Andra