我想找个人帮我理解几行代码

Question

这里的任何一个人能不能请用这个代码举例，如果可能的话，这个代码在做什么？你知道吗

def sort_by_length(words):
    t = []
    for word in words:
       t.append((len(word), word))
    t.sort(reverse=True)

    res = []
    for length, word in t:
      res.append(word)
    return res

反向的意思是什么？反向是什么？我确实明白人们用什么方法来表示，而不是用反向来表示什么

Answer 1

按长度对单词排序

w = ["abcd", "za", "wyya", "dssffgdg"]
print sort_by_length(w);

http://ideone.com/jRzatV

Answer 2

它返回一个单词列表，从最长到最短排序，然后从z到a

你也可以做同样的事

def sort_by_length(words):
    return sorted(words, key=lambda w: (len(w), w), reverse=True)

从最长到最短，从a到z排序可能更有意义

def sort_by_length(words):
    return sorted(words, key=lambda w: (-len(w), w))

Answer 3

def sort_by_length(words):
t = [] # empty list
for word in words:# iterating over given words
   t.append((len(word), word)) # appending a word into the list "t" as tupel. e.g word "hello" as (5, "hello")
t.sort(reverse=True) # sorts all tupels in reverse-order

res = []
for length, word in t:
  res.append(word) # extracts just the words out of the tupels e.g. (5, "hello") => "hello"
return res # return words ordered