Challenge - Movie Ratings

You’re given a 10x2 array of floats where each row represents a movie. The first column represents the movie’s rating and the second column represents the director’s rating.

Create a third column that represents the overall rating. The overall rating is equal to the movie rating if it exists, otherwise the director’s rating.

import numpy as np

generator = np.random.default_rng(123)
ratings = np.round(generator.uniform(low=0.0, high=10.0, size=(10, 2)))
ratings[[1,2,7,9], [0,0,0,0]] = np.nan

print(ratings)
# [[ 7.  1.]
#  [nan  2.]
#  [nan  8.]
#  [ 9.  3.]
#  [ 8.  9.]
#  [ 5.  2.]
#  [ 8.  2.]
#  [nan  6.]
#  [ 9.  2.]
#  [nan  5.]]

[[ 7.  1.]
 [nan  2.]
 [nan  8.]
 [ 9.  3.]
 [ 8.  9.]
 [ 5.  2.]
 [ 8.  2.]
 [nan  6.]
 [ 9.  2.]
 [nan  5.]]

nan_cols = np.isnan(ratings[:, 0])
final_ratings = np.zeros(ratings.shape[0])
final_ratings[nan_cols] = ratings[:, 1][nan_cols]
final_ratings[~nan_cols] = ratings[:, 0][~nan_cols]
np.concatenate((ratings, np.array([final_ratings]).T), axis=-1)

array([[ 7.,  1.,  7.],
       [nan,  2.,  2.],
       [nan,  8.,  8.],
       [ 9.,  3.,  9.],
       [ 8.,  9.,  8.],
       [ 5.,  2.,  5.],
       [ 8.,  2.,  8.],
       [nan,  6.,  6.],
       [ 9.,  2.,  9.],
       [nan,  5.,  5.]])