Python代碼逐行含義

Question

我有一個代碼，需要逐行獲取此 python 代碼的含義。

marksheet = []
for i in range(0,int(input())):
    marksheet.append([raw_input(), float(input())])

second_highest = sorted(list(set([marks for name, marks in marksheet])))[1]
print('\n'.join([a for a,b in sorted(marksheet) if b == second_highest]))

Answer 1

我強烈建議您通過python 教程轉到 go

只是為了您對這段代碼的理解，我添加了注釋。

#initialising an empty list!
marksheet = [] 

#iterating through a for loop starting from zero, to some user input(default type string) - that is converted to int
for i in range(0,int(input())): 
    #appending user input(some string) and another user input(a float value) as a list to marksheet
    marksheet.append([raw_input(), float(input())]) 

#[marks for name, marks in marksheet] - get all marks from list
#set([marks for name, marks in marksheet]) - getting unique marks
#list(set([marks for name, marks in marksheet])) - converting it back to list
#sorting the result in decending order with reverse=True and getting the value as first index which would be the second largest.
second_highest = sorted(list(set([marks for name, marks in marksheet])),reverse=True)[1] 

#printing the name and mark of student that has the second largest mark by iterating through the sorted list.
#If the condition matches, the result list is appended to tuple  -`[a for a,b in sorted(marksheet) if b == second_highest])` 
#now join the list with \n - newline to print name and mark of student with second largest mark
print('\n'.join([a for a,b in sorted(marksheet) if b == second_highest]))

希望能幫助到你！

Answer 2

會在評論中這樣做，但我還沒有 50 的聲譽：

您不需要在 second_highest 上使用 sorted 但顯然依賴它不是一個好習慣所以您可以保持排序。 在已經排序的列表上調用 sorted 無論如何都不會使用很多資源。

second_highest = sorted(list(set([marks for name, marks in marksheet])))[1]

此外，如果列表包含類似 [1,3,2,5,3,2,1] 的內容，它將給出 2 作為結果而不是 1，因為集合刪除了所有重復項。

如果要保留重復項，請使用：

second_highest = sorted([marks for name, marks in marksheet]))[1]