过滤数组数组

Question

我有这个包含位置和时间信息的数组：

my_array[:5]
[['39.921712' '116.472343' '0' '13' '39298.1462037037' '2007-08-04' '03:30:32']
 ['42.161385' '123.660773' '0' '221' '39298.6697337963' '2007-08-04' '16:04:25']
 ['42.161755' '123.66135' '0' '221' '39298.6697569444' '2007-08-04' '16:04:27']
 ['42.16194' '123.661638' '0' '221' '39298.6697685185' '2007-08-04' '16:04:28']
 ['39.907285' '116.448303' '0' '98' '39298.1581134259' '2007-08-04' '03:47:41']]

每个数组的第一个和第二个元素是位置的latitude 和longitude。

我想过滤 my_array 以仅包含 latitude 介于 39.45 - 40.05 和 longitude 介于 115.416 - 117.5 之间的数组。

预期结果：

my_array_sorted
[['39.921712' '116.472343' '0' '13' '39298.1462037037' '2007-08-04' '03:30:32']
 ['39.907285' '116.448303' '0' '98' '39298.1581134259' '2007-08-04' '03:47:41']]

Answer 1

您可以通过列表推导来做到这一点：

data = [['39.921712', '116.472343', '0', '13', '39298.1462037037', '2007-08-04', '03:30:32'],
 ['42.161385', '123.660773', '0', '221', '39298.6697337963', '2007-08-04', '16:04:25'],
 ['42.161755', '123.66135', '0', '221', '39298.6697569444', '2007-08-04', '16:04:27'],
 ['42.16194', '123.661638', '0', '221', '39298.6697685185', '2007-08-04', '16:04:28'],
 ['39.907285', '116.448303', '0', '98', '39298.1581134259', '2007-08-04', '03:47:41'],]

filtered = [i for i in data
            if 39.45 < float(i[0]) < 40.05
            and 115.416 < float(i[1]) < 117.5]

print(filtered)

输出：

[['39.921712', '116.472343', '0', '13', '39298.1462037037', '2007-08-04', '03:30:32'],
['39.907285', '116.448303', '0', '98', '39298.1581134259', '2007-08-04', '03:47:41']]

Answer 2

您应该查看接受谓词和您的列表的python's filter method，并只保留完成谓词的元素。

这是从上述文档中摘录的示例：

number_list = range(-5, 5)
less_than_zero = list(filter(lambda x: x < 0, number_list))
print(less_than_zero)

# Output: [-5, -4, -3, -2, -1]

在您的情况下，它应该如下所示：

my_array_sorted = list(filter(lambda array: 39.45 < array[0] < 40.05 and 115.416 < array[1] < 117.5))