【Python】How to get the second largest value of an array when grouped by another array? - 101 Numpy Exercises
Q:
setosaで二番目に長いpetallengthは何？
# Input url = 'https://archive.ics.uci.edu/ml/machine-learning-databases/iris/iris.data' iris = np.genfromtxt(url, delimiter=',', dtype='object') names = ('sepallength', 'sepalwidth', 'petallength', 'petalwidth', 'species')
A:
# Import iris keeping the text column intact url = 'https://archive.ics.uci.edu/ml/machine-learning-databases/iris/iris.data' iris = np.genfromtxt(url, delimiter=',', dtype='object') # Solution # Get the species and petal length columns petal_len_setosa = iris[iris[:, 4] == b'Iris-setosa', 2].astype('float') # Get the second last value np.unique(np.sort(petal_len_setosa))[-2] #> 1.7
