Python method to sort object arrays

In Python, you can usesorted()Function or()Method to correctObject array(such as a tuple or list in a list) sorted by the second value. Here are a few common methods:

1. Use the sorted() function (returns the new sorted list)

data = [{1, 2}, {2, 1}]  # Note: Collections are unordered and cannot be sorted directly. Tuples or lists should be used here.
# The correct data structure should be a list of tuples or listsdata = [(1, 2), (2, 1)]  # or [[1, 2], [2, 1]]
# Sort by second elementsorted_data = sorted(data, key=lambda x: x[1])
print(sorted_data)  # Output: [(2, 1), (1, 2)]

2. Use the() method (sort in place, not return the new list)

data = [(1, 2), (2, 1)]
(key=lambda x: x[1])
print(data)  # Output: [(2, 1), (1, 2)]

3. If the data structure is a set, the set itself is unordered and cannot be sorted directly. It needs to be converted to a tuple or a list first.

data = [{1, 2}, {2, 1}]

# Convert a collection to a tuple or list and sort itsorted_data = sorted([tuple(s) for s in data], key=lambda x: x[1])
print(sorted_data)  # Output: [(1, 2), (2, 1)] or [(2, 1), (1, 2)] because the order of the set is uncertain

Things to note

gather(set) is disordered, so{1, 2}and{2, 1}is the same set, and the order cannot be distinguished. If order is required, tuples should be used (tuple) or list (list）。
key=lambda x: x[1]Represents sorting by the second value of each element (index 1) (array subscript starts at 0).

Sample code (tuples or lists are recommended)

# Use Tuplesdata = [(1, 2), (2, 1), (3, 0)]
sorted_data = sorted(data, key=lambda x: x[1])
print(sorted_data)  # Output: [(3, 0), (2, 1), (1, 2)]
# Use listdata = [[1, 2], [2, 1], [3, 0]]
(key=lambda x: x[1])
print(data)  # Output: [[3, 0], [2, 1], [1, 2]]

If you do need to work with a collection, make sure to convert it to an ordered data structure (such as a tuple or a list) before sorting.

Extension: Inverse sorting

By default, followAscending orderFor sorting, if we need to sort in reverse order, we can add more parametersreverse=True(This parameter is by defaultFalse),For example:

data = [(1, 2), (2, 1), (3, 0)]
sorted_data = sorted(data, key=lambda x: x[1], reverse=True)
(key=lambda x: x[1], reverse=True)

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