ss=sorted(s,key=lambda x : a.count(x),reverse=True)怎么理解
时间: 2023-11-26 11:02:50 浏览: 29
这段代码是对列表 `s` 进行排序,排序的依据是列表 `a` 中每个元素在列表 `s` 中的出现次数,出现次数多的元素排在前面。
具体来说,`a.count(x)` 表示计算列表 `a` 中元素 `x` 出现的次数。lambda 函数 `lambda x : a.count(x)` 则将每个元素 `x` 映射为其在列表 `a` 中出现的次数。这样,`sorted()` 函数便按照出现次数从大到小对列表 `s` 进行排序,排序结果存储在变量 `ss` 中。 `reverse=True` 表示按照降序排序,即出现次数多的元素排在前面。
相关问题
ns=sorted(sorted(s),key=lambda x:s.count(x),reverse=True)[0]
This line of code sorts the characters in a string 's' in ascending order, and then sorts them again in descending order based on their frequency of occurrence in the string. Finally, it selects the character with the highest frequency of occurrence and assigns it to the variable 'ns'.
Here's a step-by-step breakdown of how this line of code works:
1. `sorted(s)` sorts the characters in the string 's' in ascending order.
2. `sorted( ... , key=lambda x: s.count(x), reverse=True)` sorts the characters again, but this time based on their frequency of occurrence in the string. The `key` parameter specifies that the lambda function `lambda x: s.count(x)` should be used to determine the sorting order. This lambda function takes a character 'x' and returns the number of times it appears in the string 's'. The `reverse` parameter is set to `True` to sort the characters in descending order.
3. `[0]` selects the first character in the sorted list, which has the highest frequency of occurrence.
4. Finally, this character is assigned to the variable 'ns'.
ns=sorted(sorted(s),key=lambda x:s.count(x),reverse=True)原理
这行代码的作用是将字符串s按照字符出现次数的降序排列,并返回排列后的字符列表ns。
具体实现方法是:先对字符串s进行排序,然后再按照字符出现次数进行排序。在按照字符出现次数排序时,使用了lambda表达式来定义排序规则,即按照字符出现次数降序排列。
lambda表达式是一种匿名函数,它可以接受任意数量的参数,并返回一个表达式的值。在这里,lambda表达式接受一个字符x作为参数,并返回该字符在字符串s中出现的次数。这样,sorted函数就可以根据字符出现次数来对字符串进行排序了。
最终得到的排序结果是一个字符列表ns,其中每个字符按照出现次数的降序排列。