python - 返回循环字典中键的第一个值条目的最大值

Question

我想获得第一个值 10,40 -> 40 中的最大值。我可以在下面使用它，但是一行中是否有 python 方式而不是 for 循环

    soilLayer[0] = [ 10,    50,    0.3,   1600, 1800,    5,  30 ]
    soilLayer[1] = [ 40,    50,    0.3,   1600, 1800,    5,  30 ]
    heigth = []
    position = 0
    for name in sorted( soilLayer.keys() ):
        heigth.append( soilLayer[name][position] )
    print( max( heigth ) )

Answer 1

native Python 中有一些解决方案:

soilLayer = {0: [ 10,    50,    0.3,   1600, 1800,    5,  30 ],
             1: [ 40,    50,    0.3,   1600, 1800,    5,  30 ]}


# turn each list into an iterator, apply next to each, then find maximum
res = max(map(next, map(iter, soilLayer.values())))  # 40

# create a list of first values, then calculate maximum    
res = max(list(zip(*soilLayer.values()))[0])  # 40

# use generator comprehension, most Pythonic
res = max(x[0] for x in soilLayer.values())  # 40

# functional equivalent of generator comprehension
from operator import itemgetter
res = max(map(itemgetter(0), soilLayer.values()))  # 40

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另一种方法，如果您喜欢使用第 3 方库，那就是使用 numpy:

import numpy as np

res = np.array(list(soilLayer.values()))[:, 0].max()  # 40.0