Python2D陣列排序未顯示實際結果

我正在嘗試對二維陣列進行排序，我嘗試了很多方法但它不起作用。我不知道這里發生了什么

    from operator import itemgetter
    import pprint
    arr=[['0.55070000', '879.00000000'], ['0.55350000', '879.00000000'], ['0.55640000', '879.00000000'], ['0.56210000', '879.00000000'], ['0.56490000', '879.00000000'], ['0.56780000', '879.00000000'], ['0.57060000', '879.00000000'], ['0.54500000', '899.00000000'], ['0.56370000', '901.00000000'], ['0.53070000', '908.00000000'], ['0.57350000', '916.00000000'], ['0.55000000', '9172.00000000'], ['0.56300000', '939.00000000'], ['0.54490000', '94.00000000'], ['0.56040000', '96.00000000'], ['0.54960000', '999.00000000']]
    # sorted(floatarry, key=itemgetter(1))
    sorted(arr,key=lambda x:x[1])
    pprint.pprint(arr)
    # from operator import itemgetter
    
    #############################################################
    # columnIndex = 1
    # # Sort 2D numpy array by 2nd Column
    
    # arr2D = np.array(arr)
    
    # sortedArr = arr2D[arr2D[:,columnIndex].argsort()]
    # print('Sorted 2D Numpy Array')
    # print(sortedArr)

result 
[['0.55070000' '879.00000000']
['0.55350000' '879.00000000']
['0.55640000' '879.00000000']
['0.56210000' '879.00000000']
['0.56490000' '879.00000000']
['0.56780000' '879.00000000']
['0.57060000' '879.00000000']
['0.54500000' '899.00000000']
['0.56370000' '901.00000000']
['0.53070000' '908.00000000']
['0.57350000' '916.00000000']
['0.55000000' '9172.00000000']
['0.56300000' '939.00000000']
['0.54490000' '94.00000000']
['0.56040000' '96.00000000']
['0.54960000' '999.00000000']]

最后 4 和 5 行沒有顯示錯誤結果

uj5u.com熱心網友回復：

該sorted()函式不會改變它arr本身，它只是回傳一個排序串列，然后您必須將其分配給某個變數。所以這樣做：

from operator import itemgetter
import pprint
arr=[['0.55070000', '879.00000000'], ['0.55350000', '879.00000000'], ...]
sorted_arr = sorted(arr,key=lambda x:x[1])
pprint.pprint(sorted_arr)

uj5u.com熱心網友回復：

您正在使用字串對陣列進行排序。將它們轉換float為 lambda 函式，然后嘗試 -

注意：確保分配排序函式的輸出。

arr_sorted = sorted(arr, key=lambda x: float(x[1]))
arr_sorted

[['0.54490000', '94.00000000'],
 ['0.56040000', '96.00000000'],
 ['0.55070000', '879.00000000'],
 ['0.55350000', '879.00000000'],
 ['0.55640000', '879.00000000'],
 ['0.56210000', '879.00000000'],
 ['0.56490000', '879.00000000'],
 ['0.56780000', '879.00000000'],
 ['0.57060000', '879.00000000'],
 ['0.54500000', '899.00000000'],
 ['0.56370000', '901.00000000'],
 ['0.53070000', '908.00000000'],
 ['0.57350000', '916.00000000'],
 ['0.56300000', '939.00000000'],
 ['0.54960000', '999.00000000'],
 ['0.55000000', '9172.00000000']]

如果您希望按降序排序，請將reverse=True其sorted作為引數添加。

如果您想在排序后使用更多數值運算處理這個陣列，那么我建議首先將完整陣列轉換為浮點值，然后進行排序或其他操作。

arr2 = [[float(j) for j in i] for i in arr]
arr_sorted = sorted(arr2, key=lambda x: x[1])
arr_sorted

[[0.5449, 94.0],
 [0.5604, 96.0],
 [0.5507, 879.0],
 [0.5535, 879.0],
 [0.5564, 879.0],
 [0.5621, 879.0],
 [0.5649, 879.0],
 [0.5678, 879.0],
 [0.5706, 879.0],
 [0.545, 899.0],
 [0.5637, 901.0],
 [0.5307, 908.0],
 [0.5735, 916.0],
 [0.563, 939.0],
 [0.5496, 999.0],
 [0.55, 9172.0]]

標籤：Python 数组 麻木的 排序

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