Python pandas linear regression groupby

Question

I am trying to use a linear regression on a group by pandas python dataframe:

This is the dataframe df:

  group      date      value
    A     01-02-201         


        

Answer 1

As a newbie I cannot comment so I will write it as a new answer. To solve an error:

Runtime Error: ValueError : Expected 2D array, got scalar array instead

you need to reshape delta value in line:

return np.squeeze(LinearRegression().fit(X, y).predict(np.array(delta).reshape(1, -1)))

Credit stays for you piRSquared