There are some nice exercises here, good work. For question 48 it might be simpler to just write np.sort(a)[-5:] instead of using argsort() and then using

There are some nice exercises here, good work. For question 48 it might be simpler to just write np.sort(a)[-5:] instead of using argsort() and then using fancy indexing. Better yet, use np.partition(a, kth=-5)[-5:] which scales linearly with the size of the array. Also, the one-hot encoding puzzle (51) would be more efficiently solved using (arr[:, None] == np.unique(arr)).view(np.int8) In general, `for` loops over NumPy arrays should be avoided where at all possible.