按名称的高分对名称进行排序 [英] Sorting names by their high scores

问题描述

我想按分数对姓名列表进行排序. 到目前为止，我是

I want to sort a list of names by their score. What I have so far is

file = open("scores.txt", 'r')
for line in file:
    name = line.strip()
    print(name)
file.close()

我不确定如何对它们进行排序.

I'm unsure how to sort them.

这是文件内容:

Matthew, 13
Luke, 6
John, 3
Bobba, 4

我希望输出为:

John 3
Bobba 4
Luke 6
Matthew 13

任何人都可以帮忙吗?

推荐答案

您可以使用.split(',')方法将一行拆分为单独的部分，然后使用int()将分数转换为数字. .sort()方法在适当的位置对列表进行排序，而key告诉它按什么排序.

you can use the .split(',') method to split a line into its separate parts, then use int() to convert the score to a number. The .sort() method sorts a list in place, and the key tells it what to sort by.

scores = []
with open("scores.txt") as f:
    for line in f:
        name, score = line.split(',')
        score = int(score)
        scores.append((name, score))

scores.sort(key=lambda s: s[1])

for name, score in scores:
    print(name, score)

这将为您提供按排序顺序包含(名称，分数)对的元组列表.如果要打印它们之间并用逗号隔开(以保持一致)，请将打印内容更改为print(name, score, sep=', ')

This will give you a list of tuples containing (name, score) pairs in sorted order. If you want to print them out with a comma in between them (to keep it consistent) change the print to print(name, score, sep=', ')

输入文件的读取也可以表示为一行(大)

The reading of the input file can also be expressed as one (big) line

with open("scores.txt") as f:
    scores = [(name, int(score)) for name, score in (line.split(',') for line in f)]

---

key=的简要说明:

---

A brief explanation of the key=:

lambda函数是匿名函数，即没有名称的函数.通常，仅在需要小操作的功能时使用它们. .sort有一个可选的key关键字参数，该参数采用一个函数并使用该函数的返回值对对象进行排序.

a lambda function is an anonymous function, that is, a function without a name. You generally use these when you need a function only for a small operation. .sort has an optional key keyword argument that takes a function and uses the return of that function in sorting the objects.

因此，该lambda也可以写为

def ret_score(pair):
    return pair[1]

然后您可以编写.sort(key=ret_score)，但是由于我们实际上并不需要该函数，因此无需声明它. lambda语法为

And you could then write .sort(key=ret_score) but since we dont really need that function for anything else, its not necessary to declare it. The lambda syntax is

lambda <arguments> : <return value>

因此，此lambda取一对，并返回其中的第二个元素.您可以保存lambda并根据需要将其用作常规功能.

So this lambda takes a pair, and returns the second element in it. You can save a lambda and use it like a regular function if you wish.

>>> square = lambda x: x**2 # takes x, returns x squared
>>> square(3)
9
>>> square(6)
36

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